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[Seminar] [Kohana: A Lightweight PHP Framework]

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[Brandon Liu] [Harvard University]

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[This is CS50.] [CS50.TV]

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>> Hi everyone. My name is Brandon.

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I'm a junior here at the college doing computer science, and today we're going to talk about

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Kohana, which is a PHP web development framework.

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Today is going to be a live coding seminar,

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so I'm basically going to spend 5-10 minutes explaining what Kohana is,

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and then I'm literally going to build a super simple blog

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for you right here literally from scratch.

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We're going to download the code from the Kohana website,

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and we're going to start building a blog, and hopefully it'll be very instructive,

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because you'll see perhaps maybe I'll make some mistakes,

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and you'll see me recover from them,

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or you'll see my thought process as I build through this blog,

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and meanwhile, you'll also get familiar with the framework itself.

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Hopefully it'll be a very instructive exercise.

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>> First, what exactly is a framework?

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If you've been taking CS50 so far, you haven't really worked with any 

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frameworks yet, and the thing is this.

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You've probably done 1 web development pset already,

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and let's say you continue to build websites and keep building websites.

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You'll start to notice a few things.

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The first thing you'll notice is that you're probably doing the same things

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over and over again all the time,

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things like cleaning user input data, 

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things like organizing your files in a certain way.

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The other thing you'll also probably notice is that your code

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may start to become very, very messy,

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and you may leave it messy and just have a very hard time maintaining it,

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or you may start to structure your code and making it modular

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in certain ways to make it more maintainable.

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>> This is where web frameworks basically came in.

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These people who had built a lot of websites, they said,

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"We don't need to redo this every single time we build a website."

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"Why don't we just make a package that does all these things for you 

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every single time you want to build a website?"

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And so that when you make a new website,

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you just focus on what exactly this particular website is about.

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You don't need to repeat all the various configuration

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and separation of codes and rewriting code

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that you often have to do when you're making websites.

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The idea is that a framework allows you to write a higher-level code

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without having to worry about lower-level details.

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A lower-level detail might be something like

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dealing with cleaning user input data.

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That's something that you shouldn't really need to worry about.

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You should focus on what your web allocation is actually about.

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It eliminates a lot of boilerplate code.

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It is an architecture for your project.

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>> The most popular one would be Model-View-Controller,

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which I'm going to talk about in a second.

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And a lot of times these frameworks embody a set of procedures,

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rules, and best practices for you to use 

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so that when you adopt the web framework

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you have to write your code in a certain way,

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and it's generally an agreed upon set of principles

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by the community that is generally accepted to be

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a good way of writing code.

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It makes your code more maintainable, more usable,

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so on and so forth.

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And finally, the thing I want to emphasize about frameworks

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versus libraries is this idea about inversion of control, and the thing is this.

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The difference between a library and a framework is that with a library

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you are still writing the main program,

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and you're sort of invoking the library

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and calling upon the library to do something for you.

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The difference between a library and a framework

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is that the framework starts out with the control,

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and it invokes your code,

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so you can think of it as--this is why it's called a framework--

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the framework provides this frame and structure for your code,

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and you fill in the holes,

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and this will become more apparent in a second

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when you see me start to write code within the context of the framework.

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You'll see that I'm filling in the gaps,

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and the framework is kind of controlling all the moving pieces,

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and I have to put the pieces in the right places.

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>> Today we're going to talk about Kohana, 

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which is one of many PHP frameworks.

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There are web frameworks, and there are ones in virtually every single language,

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and I'm picking Kohana because Kohana is arguably

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and generally recognized as the easiest PHP framework to pick up.

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It's the most lightweight.

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There are other ones out there that come with many, many more features,

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but they tend to be more difficult to pick up.

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And finally, Kohana uses the MVC architecture.

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It's lightweight enough that we can literally build a project

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right here right in front of your eyes, and you can pretty much

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follow along pretty easily.

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>> What is the MVC architecture?

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It stands for Model-View-Controller,

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and maybe if you think about the code you've been writing so far

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for some of your web development psets 

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you may be able to see some of this, but usually when you start writing

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a more complex web application,

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the division between these 3 segments becomes more and more evident.

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I laid out the MVC here sort of as a stack,

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and often you'll hear people talk about stacks in web development,

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and this is to illustrate the idea that

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each layer, each component really tries to only communicate

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between 2 other components.

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Someone accesses your website as a client or a browser.

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They interact with your program through the view code.

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The view code interacts with the controller.

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The controller interacts with the model, 

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and the model interacts with the SQL database.

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And there is no hopping in between if you write your code properly.

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>> What do these things do?

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The model essentially is the piece of code that deals with your data.

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Anything that deals with your database, with the objects that you store,

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or retrieving those objects in the database,

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that's all handled by the model.

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Maybe you have objects in your database.

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We're going to create a model having to do with posts,

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so a post may have some attributes to it.

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You may have functions around storing those posts or retrieving posts

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or filtering the posts and so on and so forth,

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and that's all the code that's handled by the model.

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The controller is sort of the application logic,

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and a lot of different things can go in the application logic.

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If you're talking to a different API,

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that may be where you're dealing with the application logic.

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If you're trying to have to bring in data from multiple different models

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and have to combine them in some way, that often may be handled by the controller.

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For example, on Facebook, if you friend someone,

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then perhaps that act of establishing that relationship

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may be done by the controller.

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>> And finally, the view is the code that's generating what you actually see.

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A lot of times I think in the CS50 psets

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they don't really encourage you guys to separate these 3 things.

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You'll probably have this big, long file where at the top

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you make some SQL query and maybe do some processing

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on the data you retrieved from the database,

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and then you have all your HTML at the bottom.

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And you may find that as you create more and more pages

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that you're going to have some code repetition, and also,

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the thing is your file gets really big and long

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and becomes unwieldy to manage.

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The reason why MVC is so well regarded

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is for a number of reasons.

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The first thing is something called separation of concerns

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which is the idea that when you have--

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ideally 1 piece of code should do 1 thing and do it really well,

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and you shouldn't combine pieces of code that do disparate things.

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For example, view code and model code,

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they don't really have to be related.

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They don't have to be in the same files, so when you can, separate them out

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so it's easy to maintain.

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>> The other thing is code reuse.

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You may find yourself writing the same SQL query or doing 

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similar queries that could be abstracted into 1 function,

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and that's the idea behind models and controllers,

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having it in a separate function that you can reuse in different places in your project.

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And finally, that's tied to DRYing your code,

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or not repeating yourself, don't repeat yourself.

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This is very comprehensible in development.

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Whenever you can, you don't want to repeat yourself, because if you repeat yourself,

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 it's much more costly to maintain.

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If you want to change 1 thing, you have to change it everywhere,

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and that leads to bugs, and it's horrible.

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>> All right.

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Any questions so far about Kohana at all?

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Great.

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Now we're going to dive into the live coding session,

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and hopefully everything goes well.

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I am going to basically build this website

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on one of my remote servers, and that way you guys can also

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see the website and access the website,

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and also the environment is better configured than my remote machine,

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because it's running Linux instead of OS X.

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We're literally going to start.

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KohanaFramework.org.

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I'm going to download the code from the website.

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I'm going to copy the link address,

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go to my server, download it,

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and I'm going to extract it.

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>> [Student] What's the largest you can make the text?

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[Brandon Liu] Is that better?

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[Student] Is that doable?>>[Brandon Liu] Yeah, that's fine.

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I downloaded a ZIP file and unzipped that into a directory called Kohana,

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and we're going to rename that CS50-Kohana,

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and let's go in.

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Awesome.

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Here you see a bunch of different files.

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Most of you can ignore--we're not going to go through every single file that's in here

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because of our time constraints,

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but generally when you install Kohana, the first thing you do

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is you go to the directory,

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and you'll basically do some environment tests and whatnot

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to make sure your environment is properly set to run Kohana

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and make sure that everything is all right.

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You can see most things passed, but generally you always run into this 1 problem 

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where it complains that some directory is not writable,

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and that's because of some permissions.

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I don't know how much you guys have learned about file permissions in CS50,

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but if you do web development, you're going to run into this issue a lot.

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I'm going to make it writable

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and I think I also have to--there we go.

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>> Okay, so now you can see everything passed,

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and now it will tell you to rename the install.php file.

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I'm going to move the install.php file to installed.php,

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and now if I refresh,

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it gives me some error, and this is where the debugging comes in.

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This is where you can see what's actually going to happen.

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The thing is, by default, Kohana assumes that

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your project is at the root directory of your domain,

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so it's expecting you to be at demo.brandonkliu.com.

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We have to tell it that it's actually in a subfolder.

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It's in a subfolder called CS50 Kohana.

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The thing is, it's misinterpreting CS50-Kohana

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as something else, which I'll explain to you in a second.

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But I should tell you that's something that's to be expected.

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What we're going to do is we're going to go into this folder called bootstrap.php,

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which is the configuration folder where a lot of different things are set up.

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I open that up.

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Then maybe one of the first things I'll do is change the time zone.

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>> And then let's see.

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Aha! Right here.

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There are a bunch of different configuration sayings in here,

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but the one I'm looking for is this thing called  base URL,

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and by default I get it set to Kohana,

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but I'm going to change that to CS50-Kohana,

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and I think that should fix it.

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Yes, great.

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By default, to see that it's working, it says, "Hello World."

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Where did that come from? How did we get to Hello World?

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Where exactly is the code that actually wrote that?

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To understand that, I'll introduce this concept called routing.

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Pretty much all web frameworks have the concept called routing,

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which is the piece of the software that will map a certain URL

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to a certain piece of code within your framework.

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For example, if you have some URL and you go to some URL like foo.com/blog/all

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then what the framework is going to do--or at least what Kohana is going to do--

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is it's going to find a class called controller blog,

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and it's going to run the function named action all.

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I know I'm talking about class and functions,

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and I know you guys haven't covered classes and functions

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in CS50 yet, but for now,

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you can think of classes as just a group of functions,

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a way of grouping functions together.

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That's really all you need to know.

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>> Now if we look at our folder structure,

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inside the application folder there is another folder called classes,

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and the other folders are called Controller and Model.

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If you look inside the Controller folder,

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we see that there is a file called Welcome,

248
00:12:56,330 --> 00:13:00,370
and you can see here is a class called Controller Welcome,

249
00:13:00,370 --> 00:13:02,340
and there is a function called Action Index,

250
00:13:02,340 --> 00:13:06,360
and what it does is it sets the body of your response to Hello World.

251
00:13:06,360 --> 00:13:08,730
That's where the code is being written.

252
00:13:08,730 --> 00:13:11,610
The other question is, well, I didn't go to 

253
00:13:11,610 --> 00:13:13,680
blah, blah, blah, /welcome/index.

254
00:13:13,680 --> 00:13:16,250
How did I end up here?

255
00:13:16,250 --> 00:13:20,410
Well, that's simply because 

256
00:13:20,410 --> 00:13:22,410
here at the bottom of our bootstrap file

257
00:13:22,410 --> 00:13:24,550
where we set our routes

258
00:13:24,550 --> 00:13:26,570
you can see that they set some defaults for you.

259
00:13:26,570 --> 00:13:28,990
The default controller is Welcome. The default action is Index.

260
00:13:28,990 --> 00:13:31,600
That's why when we put nothing in there it automatically went to the Welcome controller

261
00:13:31,600 --> 00:13:33,940
and the index Action.

262
00:13:33,940 --> 00:13:37,460
>> Everything make sense so far?

263
00:13:37,460 --> 00:13:40,850
Now, you can do more than just go to Controller

264
00:13:40,850 --> 00:13:43,670
and a specific action.

265
00:13:43,670 --> 00:13:48,480
You can also pass in parameters to the controller.

266
00:13:48,480 --> 00:13:56,390
Just as an example, 

267
00:13:56,390 --> 00:14:04,070
I'm going to add another action to this controller to show you.

268
00:14:04,070 --> 00:14:09,130
Let's call this action Echo, because it's going to tell you whatever you give it,

269
00:14:09,130 --> 00:14:17,510
and so I'm basically going to grab

270
00:14:17,510 --> 00:14:20,960
a parameter that's going to be sent through me to the routing program,

271
00:14:20,960 --> 00:14:24,440
and as you can see here,

272
00:14:24,440 --> 00:14:28,440
this line right here, you can see that

273
00:14:28,440 --> 00:14:31,270
this basically means you have controller, and you have a /, 

274
00:14:31,270 --> 00:14:33,480
and you have action, and you have another /,

275
00:14:33,480 --> 00:14:39,140
and that's going to be parameters, and because we have this name ID

276
00:14:39,140 --> 00:14:42,450
within angle brackets, that means that we're naming this parameter ID.

277
00:14:42,450 --> 00:14:45,490
Later in my controller code if I want to grab a hold of that parameter,

278
00:14:45,490 --> 00:14:51,790
I can use the code I wrote, find the parameter named ID.

279
00:14:51,790 --> 00:14:59,290
That's what I did here, and I'm going to return and say, 

280
00:14:59,290 --> 00:15:07,090
"You said" that.

281
00:15:07,090 --> 00:15:10,760
And so now if I go to our website,

282
00:15:10,760 --> 00:15:19,550
I go to cs50-kohana/welcome/echo/Helloooo--

283
00:15:19,550 --> 00:15:21,420
oh, that's right.

284
00:15:21,420 --> 00:15:23,930
There is 1 step I left out.

285
00:15:23,930 --> 00:15:27,020
This is part of the live coding idea.

286
00:15:27,020 --> 00:15:36,100
>> Here's 1 thing. Let's see.

287
00:15:36,100 --> 00:15:38,870
So normally by default with a lot of these web applications

288
00:15:38,870 --> 00:15:42,820
you have to include this index.php thing in your URL,

289
00:15:42,820 --> 00:15:46,410
because the idea is index.php is sort of the entry point

290
00:15:46,410 --> 00:15:48,250
of your application, but of course,

291
00:15:48,250 --> 00:15:50,110
that's sort of annoying to have.

292
00:15:50,110 --> 00:15:53,790
You don't want to have index.php appear in your URL,

293
00:15:53,790 --> 00:15:56,080
and pretty much every web framework out of the box

294
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has this index.php problem,

295
00:15:58,440 --> 00:16:03,370
and so you have to take some measures to be able to remove that.

296
00:16:03,370 --> 00:16:07,540
And so in this case,

297
00:16:07,540 --> 00:16:11,450
what we're going to do is we're going to use a file called .htaccess,

298
00:16:11,450 --> 00:16:13,900
and this is something that's specific to the Apache web server,

299
00:16:13,900 --> 00:16:16,290
and it can do things like rewrite URLs

300
00:16:16,290 --> 00:16:19,350
and redirect URLs and so on and so forth,

301
00:16:19,350 --> 00:16:24,280
and Kohana is nice enough to provide a template .htaccess file that we can use.

302
00:16:24,280 --> 00:16:28,300
>> As you can see, there is a file there called example.htaccess,

303
00:16:28,300 --> 00:16:33,410
and we're going to copy that to .htaccess.

304
00:16:33,410 --> 00:16:36,950
I'm going to open this and edit it,

305
00:16:36,950 --> 00:16:40,840
and basically it does a bunch of different things.

306
00:16:40,840 --> 00:16:45,320
The key line you may want to look at is right here.

307
00:16:45,320 --> 00:16:49,840
The idea is that this sets up a rule that says, 

308
00:16:49,840 --> 00:16:56,400
"Okay, whatever you type in, prepend index.php to that."

309
00:16:56,400 --> 00:16:58,710
You can see that. 

310
00:16:58,710 --> 00:17:00,370
The .* stands for anything, match anything,

311
00:17:00,370 --> 00:17:03,300
and then the second part is index.php/$0,

312
00:17:03,300 --> 00:17:07,410
and $0 refers to whatever was matched previously.

313
00:17:07,410 --> 00:17:09,500
Does that make sense?

314
00:17:09,500 --> 00:17:12,190
But the really key thing I want to change is change this rewrite base,

315
00:17:12,190 --> 00:17:14,300
which is the URL base.

316
00:17:14,300 --> 00:17:17,780
It sort of assumes where you're working from.

317
00:17:17,780 --> 00:17:22,560
I'm going to add CS50 Kohana to that,

318
00:17:22,560 --> 00:17:26,530
and that way now if I remove the index.php,

319
00:17:26,530 --> 00:17:32,110
it should work, and I'm going to add some numbers

320
00:17:32,110 --> 00:17:36,380
to show you that it indeed did work.

321
00:17:36,380 --> 00:17:38,130
Sounds good.

322
00:17:38,130 --> 00:17:40,260
>> Any questions so far?

323
00:17:40,260 --> 00:17:42,300
[Student] How did it know to make the 123?

324
00:17:42,300 --> 00:17:44,120
Is that an argument?

325
00:17:44,120 --> 00:17:46,560
Exactly. You can think of it just like an argument.

326
00:17:46,560 --> 00:17:52,410
But the weird thing, though, is that the way Kohana does it

327
00:17:52,410 --> 00:17:54,910
is they don't do it exactly like an argument.

328
00:17:54,910 --> 00:17:56,930
You have to grab it like this.

329
00:17:56,930 --> 00:18:01,030
You have to grab the request object and ask for the parameter that's named ID,

330
00:18:01,030 --> 00:18:03,240
and that name ID comes from that bootstrap file

331
00:18:03,240 --> 00:18:06,990
that I showed earlier, and the name ID was in those angle brackets,

332
00:18:06,990 --> 00:18:11,580
and that's how you grab those parameters.

333
00:18:11,580 --> 00:18:14,010
Awesome.

334
00:18:14,010 --> 00:18:17,550
Any other questions?

335
00:18:17,550 --> 00:18:20,500
Like I said, controllers, they handle application logic,

336
00:18:20,500 --> 00:18:22,980
so that's 1 instance where you can see that's--

337
00:18:22,980 --> 00:18:24,830
it's very basic, but it's still application logic,

338
00:18:24,830 --> 00:18:27,980
the idea of grabbing the parameter and creating a new string

339
00:18:27,980 --> 00:18:31,920
that says, "You said blah," and then spitting that back to you.

340
00:18:31,920 --> 00:18:34,030
And generally what you do is you create different controllers.

341
00:18:34,030 --> 00:18:36,450
You create separate controllers for different parts of your website.

342
00:18:36,450 --> 00:18:38,160
>> Today we're going to make a very simple website,

343
00:18:38,160 --> 00:18:40,420
and it's going to be a very basic blog.

344
00:18:40,420 --> 00:18:43,780
We're going to make a new controller just for the posts in a blog.

345
00:18:43,780 --> 00:18:47,060
But then if I were to also add comments to the blog post,

346
00:18:47,060 --> 00:18:50,140
then I would probably want to make a new controller for those comments.

347
00:18:50,140 --> 00:18:53,380
If I wanted to add users, I would probably add a new controller for those users,

348
00:18:53,380 --> 00:18:57,000
and in general, the idea is that whenever you have a new model,

349
00:18:57,000 --> 00:18:59,630
a new data object that you're dealing with,

350
00:18:59,630 --> 00:19:02,970
you have a single controller for that data object.

351
00:19:02,970 --> 00:19:04,370
Today we're only going to work with 1 data object, 

352
00:19:04,370 --> 00:19:06,250
and that's going to be posts, 

353
00:19:06,250 --> 00:19:08,710
and also you can think of data objects as corresponding to tables.

354
00:19:08,710 --> 00:19:12,160
Generally each table corresponds to 1 type of data object,

355
00:19:12,160 --> 00:19:15,160
so the post table will have 1 post model,

356
00:19:15,160 --> 00:19:18,230
which will have 1 post controller corresponding to that,

357
00:19:18,230 --> 00:19:22,190
and the same for comments, the same for users, and so on and so forth.

358
00:19:22,190 --> 00:19:24,070
And that's a general rule of thumb.

359
00:19:24,070 --> 00:19:27,460
There are going to be special cases where you may differ from that,

360
00:19:27,460 --> 00:19:29,300
but 90% of the time that's what you're going to be doing, 

361
00:19:29,300 --> 00:19:32,810
and I'll show you that's what we're going to be doing today.

362
00:19:32,810 --> 00:19:35,490
1 more concept before we dive back into the code,

363
00:19:35,490 --> 00:19:37,710
this idea of object relational mapping.

364
00:19:37,710 --> 00:19:41,200
>> You guys have already done a web development pset,

365
00:19:41,200 --> 00:19:43,820
and you've seen that you make an SQL query,

366
00:19:43,820 --> 00:19:46,510
and whatever it returns to you are rows.

367
00:19:46,510 --> 00:19:50,040
You get these rows, and you index them by some name,

368
00:19:50,040 --> 00:19:55,480
the name of the column and the table,

369
00:19:55,480 --> 00:19:57,630
and that's how you work with it,

370
00:19:57,630 --> 00:19:59,290
and it can be a bit cumbersome.

371
00:19:59,290 --> 00:20:01,810
But furthermore, if you have relationships within your database,

372
00:20:01,810 --> 00:20:05,280
like for example if I have comments and posts,

373
00:20:05,280 --> 00:20:11,240
then maybe I want to grab the parent post of a comment.

374
00:20:11,240 --> 00:20:14,350
If I use just rows in SQL, then all I can get is the ID

375
00:20:14,350 --> 00:20:19,310
of the parent post and not the actual post itself.

376
00:20:19,310 --> 00:20:21,680
But when we're coding, what we actually want is to actually grab

377
00:20:21,680 --> 00:20:23,550
 the parent post itself sometimes.

378
00:20:23,550 --> 00:20:25,730
What object relational mapping does is 

379
00:20:25,730 --> 00:20:29,480
it takes the results of the database query

380
00:20:29,480 --> 00:20:32,420
and puts it into objects for you, which are much nicer to work with

381
00:20:32,420 --> 00:20:34,770
than plain arrays and rows.

382
00:20:34,770 --> 00:20:37,550
>> For example, now when I have a comment perhaps,

383
00:20:37,550 --> 00:20:40,900
and I want to grab its parent post,

384
00:20:40,900 --> 00:20:43,440
and I do maybe comment arrow post,

385
00:20:43,440 --> 00:20:45,230
then it will actually give me the post object 

386
00:20:45,230 --> 00:20:47,940
corresponding to the actual parent post, not just some ID,

387
00:20:47,940 --> 00:20:52,210
which I would otherwise have to use and make another SQL query to grab the post,

388
00:20:52,210 --> 00:20:57,430
which is cumbersome and unnecessary.

389
00:20:57,430 --> 00:21:01,840
And furthermore, by mapping all these data rows into objects,

390
00:21:01,840 --> 00:21:03,760
you can also attach more functions to objects,

391
00:21:03,760 --> 00:21:09,700
so for example, I talked about how classes are essentially groupings of functions. 

392
00:21:09,700 --> 00:21:11,620
You can think of it like that.

393
00:21:11,620 --> 00:21:15,290
For example, maybe I have this post object,

394
00:21:15,290 --> 00:21:17,830
and maybe I'd like to have some sort of function attached to it

395
00:21:17,830 --> 00:21:20,300
that basically tells me was it recently posted?

396
00:21:20,300 --> 00:21:23,570
Was it posted within the last week, true or false?

397
00:21:23,570 --> 00:21:27,320
And that's a function I can attach onto that object,

398
00:21:27,320 --> 00:21:31,300
and it's really convenient to have it in the same place,

399
00:21:31,300 --> 00:21:33,820
and there are a host of different functions you can create

400
00:21:33,820 --> 00:21:37,990
for these objects, and it's really nice to be able to attach it to a class,

401
00:21:37,990 --> 00:21:41,700
to an object, whereas if you just had rows coming from your database,

402
00:21:41,700 --> 00:21:43,790
then you can't really attach any functionality to that.

403
00:21:43,790 --> 00:21:47,850
It's literally just data.

404
00:21:47,850 --> 00:21:50,550
Any questions about that at all?

405
00:21:50,550 --> 00:21:52,710
ORMs are very common web development,

406
00:21:52,710 --> 00:21:56,330
and there are a lot of different types of ORMs,

407
00:21:56,330 --> 00:21:58,450
and Kohana has its own ORM.

408
00:21:58,450 --> 00:22:05,050
It's very basic, but you'll get a taste of what it looks like.

409
00:22:05,050 --> 00:22:08,780
>> Let's create a model for our blog posts,

410
00:22:08,780 --> 00:22:12,350
and the first thing we obviously need to do is to create an actual table

411
00:22:12,350 --> 00:22:16,680
within our database to actually store our data for those posts.

412
00:22:16,680 --> 00:22:19,260
The first thing I'm going to do is go to phpMyAdmin.

413
00:22:19,260 --> 00:22:21,410
Have you guys used phpMyAdmin before?

414
00:22:21,410 --> 00:22:23,400
Okay, awesome, so you guys already know what that is,

415
00:22:23,400 --> 00:22:32,200
and I'm going to create a new table called Kohana Posts,

416
00:22:32,200 --> 00:22:37,820
and it's going to be really simple.

417
00:22:37,820 --> 00:22:40,190
I'll have to log back in.

418
00:23:02,620 --> 00:23:04,640
All we're going to do today is have an author and a body,

419
00:23:04,640 --> 00:23:11,930
just keep it simple.

420
00:23:11,930 --> 00:23:15,620
I'm going to create that table,

421
00:23:15,620 --> 00:23:19,620
and now we just have a table representing our posts

422
00:23:19,620 --> 00:23:23,370
with 2 fields for our author and our body.

423
00:23:23,370 --> 00:23:26,290
The other thing I am going to do now is 

424
00:23:26,290 --> 00:23:29,820
configure my web application so it knows how to connect to the database,

425
00:23:29,820 --> 00:23:31,950
and this, again, is something that you'll have to do with all web applications.

426
00:23:31,950 --> 00:23:34,790
You have to tell it the user name and the password

427
00:23:34,790 --> 00:23:36,990
and the name of the database and so on and so forth

428
00:23:36,990 --> 00:23:40,000
to figure out how to actually connect to your database.

429
00:23:40,000 --> 00:23:58,710
>> In Kohana, we have something called a database module,

430
00:23:58,710 --> 00:24:02,690
and in the configuration folder we have this folder called Database,

431
00:24:02,690 --> 00:24:07,330
and as you can see, there are a bunch of settings you have to set here

432
00:24:07,330 --> 00:24:09,860
to tell it what's the user name and the password

433
00:24:09,860 --> 00:24:13,110
for the database so I can actually connect to it.

434
00:24:13,110 --> 00:24:15,010
And since I don't want you guys to actually know

435
00:24:15,010 --> 00:24:17,190
the user name and password of my database,

436
00:24:17,190 --> 00:24:23,840
I have a file where I already set it all up, and I'm going to copy and paste it over.

437
00:24:33,080 --> 00:24:36,870
Awesome.

438
00:24:36,870 --> 00:24:39,880
Okay. I think that's all the configuration I need to do,

439
00:24:39,880 --> 00:24:41,070
but let's see.

440
00:24:41,070 --> 00:24:43,720
We'll keep working in it, and if something crashes, 

441
00:24:43,720 --> 00:24:47,490
then we'll fix it.

442
00:24:47,490 --> 00:24:51,830
Now what I'm going to do is I'm going to create a new controller.

443
00:24:51,830 --> 00:24:53,190
Or actually, sorry.

444
00:24:53,190 --> 00:24:55,080
First I have to create a new model.

445
00:24:55,080 --> 00:25:01,620
I'll create a new model called Post.php,

446
00:25:01,620 --> 00:25:12,440
and what we're going to do is we're going to call it class Model_Post.

447
00:25:12,440 --> 00:25:15,390
Get some syntax highlighting on,

448
00:25:15,390 --> 00:25:19,750
and so when I say, "extends ORM," that's basically 

449
00:25:19,750 --> 00:25:21,210
some more object-oriented programming,

450
00:25:21,210 --> 00:25:23,340
which unfortunately you guys haven't learned in CS50 yet, 

451
00:25:23,340 --> 00:25:25,290
but it's pretty easy to pick up.

452
00:25:25,290 --> 00:25:27,950
It gives me all this extra functionality that comes in this ORM package,

453
00:25:27,950 --> 00:25:31,120
and so I get a bunch of extra functions and whatnot for free,

454
00:25:31,120 --> 00:25:34,810
which you'll see a bit of in a second.

455
00:25:34,810 --> 00:25:37,670
>> Right now actually all I need to do is create this class.

456
00:25:37,670 --> 00:25:39,160
I don't even need to make any function or anything,

457
00:25:39,160 --> 00:25:41,770
but I've created a class that represents the table,

458
00:25:41,770 --> 00:25:44,140
and because I've extended this ORM class,

459
00:25:44,140 --> 00:25:51,080
I get a bunch of things for free, so for now you don't have to set anything more up.

460
00:25:51,080 --> 00:25:53,530
And now what I'm going to do is I'm going to create a new controller,

461
00:25:53,530 --> 00:25:58,480
which I'm going to name blog.php,

462
00:25:58,480 --> 00:26:04,350
and I'm going to copy over the Welcome controller

463
00:26:04,350 --> 00:26:11,950
so I don't have to retype some stuff,

464
00:26:11,950 --> 00:26:20,720
and now I have to rename this.

465
00:26:20,720 --> 00:26:24,710
Now what I'm going to do to test to make sure everything is working out,

466
00:26:24,710 --> 00:26:27,820
I'm going to grab the first post from my database

467
00:26:27,820 --> 00:26:32,680
and print the body of the post on the screen.

468
00:26:32,680 --> 00:26:37,920
To do that what I'm going to do first is I'm going to save the posts

469
00:26:37,920 --> 00:26:48,770
to a variable so what we're going to do is--

470
00:26:48,770 --> 00:26:52,090
in Kohana what you do is to grab the post object

471
00:26:52,090 --> 00:26:55,380
it's kind of cumbersome, but you have to do this thing called ORM:: factory,

472
00:26:55,380 --> 00:26:57,750
and then you pass in the name of the model you want,

473
00:26:57,750 --> 00:27:00,490
and it returns the ORM object that represents that model.

474
00:27:00,490 --> 00:27:04,860
And then, like I said, when we extend the ORM object,

475
00:27:04,860 --> 00:27:07,320
we get all these methods for free, so for example, 

476
00:27:07,320 --> 00:27:09,200
we get this new function called "find all,"

477
00:27:09,200 --> 00:27:12,160
which automatically returns every single post in the database,

478
00:27:12,160 --> 00:27:14,850
which is pretty convenient.

479
00:27:14,850 --> 00:27:17,480
>> And now in the body I'm going to return

480
00:27:17,480 --> 00:27:24,860
the first post and return its body.

481
00:27:24,860 --> 00:27:27,930
And of course, I need to create a post,

482
00:27:27,930 --> 00:27:31,880
so let's insert a new post.

483
00:27:31,880 --> 00:27:37,870
I'll say, "Brandon, my very first post."

484
00:27:37,870 --> 00:27:40,010
Awesome.

485
00:27:40,010 --> 00:27:45,910
And now we're going to go to blogs

486
00:27:45,910 --> 00:27:50,960
and if all works well--oh, this is some other dumb file permission thing again.

487
00:27:50,960 --> 00:27:56,090
Hold on 1 second. It's kind of absurd.

488
00:28:06,700 --> 00:28:08,490
There we go. Okay.

489
00:28:08,490 --> 00:28:10,040
I fixed that permission problem.

490
00:28:10,040 --> 00:28:12,040
It was trying to create some files and some log,

491
00:28:12,040 --> 00:28:15,400
and the permissions, again, weren't properly set, so I made it

492
00:28:15,400 --> 00:28:18,320
so those files were writable and executable

493
00:28:18,320 --> 00:28:21,090
so it could actually log to things.

494
00:28:21,090 --> 00:28:24,220
Now it's giving me another exception saying, "class ORM not found,"

495
00:28:24,220 --> 00:28:26,960
and that's because I forgot another step.

496
00:28:26,960 --> 00:28:37,010
That's too bad.

497
00:28:37,010 --> 00:28:40,270
In the bootstrap folder file, there are these modules here,

498
00:28:40,270 --> 00:28:42,480
which you can choose to enable or disable.

499
00:28:42,480 --> 00:28:44,340
These are a bunch of different features that you can choose to use 

500
00:28:44,340 --> 00:28:46,180
within Kohana, which is sort of nice.

501
00:28:46,180 --> 00:28:49,090
>> For example, they have an authentication module

502
00:28:49,090 --> 00:28:51,170
which you can use for authenticating users.

503
00:28:51,170 --> 00:28:53,390
They have a caching module if you want to implement

504
00:28:53,390 --> 00:28:57,870
some sort of caching back end to make the application work faster and whatnot.

505
00:28:57,870 --> 00:29:02,140
We need to enable the database and the ORM module,

506
00:29:02,140 --> 00:29:04,280
because like I said, we're using the database, obviously,

507
00:29:04,280 --> 00:29:08,200
and we also need to enable the ORM module,

508
00:29:08,200 --> 00:29:12,220
because we'd like to have the extra functionality, which is nice to have.

509
00:29:12,220 --> 00:29:14,240
All I have to do is uncomment those 2 lines,

510
00:29:14,240 --> 00:29:18,760
and now if I refresh, it gave me another error.

511
00:29:18,760 --> 00:29:22,100
It says, "Class Model_Post not found."

512
00:29:22,100 --> 00:29:30,210
Now this is a good problem to have.

513
00:29:30,210 --> 00:29:37,660
Let's see.

514
00:29:37,660 --> 00:29:42,200
Make it public.

515
00:29:42,200 --> 00:29:46,450
No. Hold on.

516
00:30:11,610 --> 00:30:13,160
Oh, dear.

517
00:30:13,160 --> 00:30:18,590
I do not know why it's not able to find that.

518
00:30:18,590 --> 00:30:21,030
That's really strange.

519
00:30:21,030 --> 00:30:23,820
I have this class right here.

520
00:30:23,820 --> 00:30:28,650
I guess I might have to--oh.

521
00:30:28,650 --> 00:30:32,010
I am so dumb. I forgot to add a PHP tag.

522
00:30:32,010 --> 00:30:34,670
That's why.

523
00:30:34,670 --> 00:30:41,260
Now I have to undo that 1 change I just did.

524
00:30:41,260 --> 00:30:44,270
>> Okay. There we go.

525
00:30:44,270 --> 00:30:47,500
That was really silly. I didn't have an opening PHP tag.

526
00:30:47,500 --> 00:30:49,900
But as you can see, now it's working properly, right?

527
00:30:49,900 --> 00:30:51,240
We have 1 post.

528
00:30:51,240 --> 00:30:54,730
We grabbed the first post, and now we printed out its body.

529
00:30:54,730 --> 00:30:58,010
Great. Fantastic.

530
00:30:58,010 --> 00:31:01,470
Any questions so far?

531
00:31:01,470 --> 00:31:04,100
Nope? Any questions?

532
00:31:04,100 --> 00:31:08,340
Okay, so we just created the post model, very basic,

533
00:31:08,340 --> 00:31:10,930
and we're going to add some functions later on.

534
00:31:10,930 --> 00:31:13,600
We can add validations and filtering.

535
00:31:13,600 --> 00:31:15,650
Validations are one of the things

536
00:31:15,650 --> 00:31:18,150
that frameworks solve for you really, really well,

537
00:31:18,150 --> 00:31:21,310
and I don't think you guys had to do this for your CS50 pset,

538
00:31:21,310 --> 00:31:24,000
but if you do web development for your final project,

539
00:31:24,000 --> 00:31:26,280
you're likely going to want to do some sort of validation,

540
00:31:26,280 --> 00:31:28,290
like not having blank user names,

541
00:31:28,290 --> 00:31:31,950
maybe having a password with at least some length, things like that.

542
00:31:31,950 --> 00:31:34,750
And it's really cumbersome to implement these things by ourselves,

543
00:31:34,750 --> 00:31:37,390
and pretty much every single web framework does it for you

544
00:31:37,390 --> 00:31:41,140
and allows you to do it in a very clean way.

545
00:31:41,140 --> 00:31:44,340
And the model is where you generally express those validation rules,

546
00:31:44,340 --> 00:31:48,790
because it's validating whether a model is valid or not.

547
00:31:48,790 --> 00:31:51,350
>> But for now, we're going to put that until later,

548
00:31:51,350 --> 00:31:53,520
and for now we're going to work on another part,

549
00:31:53,520 --> 00:31:55,400
and we're going to try and make a new view

550
00:31:55,400 --> 00:31:59,580
that lists all the posts.

551
00:31:59,580 --> 00:32:02,490
The steps involved in making a new action for listing all the posts

552
00:32:02,490 --> 00:32:04,810
is to grab a list of all the posts

553
00:32:04,810 --> 00:32:11,990
and then render the list of all the posts through a view.

554
00:32:11,990 --> 00:32:16,420
Right here, fortunately enough, we already grabbed all the posts

555
00:32:16,420 --> 00:32:20,310
using this first line, the find all function,

556
00:32:20,310 --> 00:32:22,520
and now what we're going to do is so far 

557
00:32:22,520 --> 00:32:25,350
I've been directly setting the body of the response

558
00:32:25,350 --> 00:32:29,090
by passing the string, but now I want to use a view,

559
00:32:29,090 --> 00:32:31,870
and the difference between a view and just doing this

560
00:32:31,870 --> 00:32:35,330
is with a view I can have a nice, big HTML template,

561
00:32:35,330 --> 00:32:37,710
and what I can do is pass it certain variables

562
00:32:37,710 --> 00:32:42,200
and then have the view automatically populate its template

563
00:32:42,200 --> 00:32:44,690
using those variables.

564
00:32:44,690 --> 00:32:50,780
What I'll do is I'll create a new view,

565
00:32:50,780 --> 00:32:55,940
and I'll name the view something like "blog/index,"

566
00:32:55,940 --> 00:33:08,480
and I'm going to basically bind this--oh, what am I writing?

567
00:33:08,480 --> 00:33:12,910
My brain is somewhere else.

568
00:33:12,910 --> 00:33:16,600
I'm going to bind the posts variable to the view,

569
00:33:16,600 --> 00:33:19,950
so that way the view has access to this post variable.

570
00:33:19,950 --> 00:33:26,140
>> And so now I need to create this view,

571
00:33:26,140 --> 00:33:28,500
so here we have this folder called "Views,"

572
00:33:28,500 --> 00:33:32,150
and first, I'm going to create a new folder under that called "Blog."

573
00:33:32,150 --> 00:33:35,810
This is nice. That way we can have a nice hierarchy for our views.

574
00:33:35,810 --> 00:33:43,910
And then I'm going to create another file in there called "index.php."

575
00:33:43,910 --> 00:33:45,780
Awesome.

576
00:33:45,780 --> 00:33:52,930
Actually, let's have them both here.

577
00:33:52,930 --> 00:33:56,760
Making a view file is probably the simplest part of all this,

578
00:33:56,760 --> 00:33:59,090
and these are probably things you're already familiar with.

579
00:33:59,090 --> 00:34:01,240
We're going to do something really simple,

580
00:34:01,240 --> 00:34:05,360
start saying, "My list of blog posts."

581
00:34:05,360 --> 00:34:14,860
Then we can go through,

582
00:34:14,860 --> 00:34:17,920
and we can iterate through the posts array,

583
00:34:17,920 --> 00:34:21,760
grab every single post and say something like--

584
00:34:21,760 --> 00:34:25,290
maybe add a line

585
00:34:25,290 --> 00:34:42,460
and then print out the author and the body.

586
00:34:42,460 --> 00:34:44,480
That make sense so far?

587
00:34:44,480 --> 00:34:50,870
And let's see if it works.

588
00:34:50,870 --> 00:34:53,489
Nothing happened.

589
00:34:53,489 --> 00:34:55,090
I wonder why.

590
00:34:55,090 --> 00:34:58,760
Oh, I missed 1 step. Very silly of me.

591
00:34:58,760 --> 00:35:01,640
I created a view, but I didn't set the view as the response,

592
00:35:01,640 --> 00:35:03,190
so you have to do 1 more thing.

593
00:35:03,190 --> 00:35:12,610
You have to do "this response body" and set it to be the view.

594
00:35:12,610 --> 00:35:14,760
There we go.

595
00:35:14,760 --> 00:35:17,200
We have our heading, and then we have a post,

596
00:35:17,200 --> 00:35:20,500
and just for kicks, let's insert another post

597
00:35:20,500 --> 00:35:23,390
so we can see a list.

598
00:35:31,800 --> 00:35:36,650
And insert these 2 posts,

599
00:35:36,650 --> 00:35:39,500
and now if I refresh the page,

600
00:35:39,500 --> 00:35:42,060
we see all these posts here.

601
00:35:42,060 --> 00:35:44,250
>> Does that make sense so far?

602
00:35:44,250 --> 00:35:46,400
Yeah, a question? Oh, okay. 

603
00:35:46,400 --> 00:35:51,440
As you can see, we've been able to separate all these codes out

604
00:35:51,440 --> 00:35:53,920
into different sections, and then you can see it's most clear with the view code.

605
00:35:53,920 --> 00:35:57,810
This file here that represents the view,

606
00:35:57,810 --> 00:36:01,220
it only cares about representing data, displaying data.

607
00:36:01,220 --> 00:36:04,310
It gets passed some sort of data, and all it does is just show it to you.

608
00:36:04,310 --> 00:36:07,660
In all other parts of your code, you won't have to worry about any of that,

609
00:36:07,660 --> 00:36:10,480
and similarly, your view code doesn't have to worry anything about

610
00:36:10,480 --> 00:36:13,390
how to access the database and so on and so forth,

611
00:36:13,390 --> 00:36:19,950
which is really good and makes your code a lot more maintainable.

612
00:36:19,950 --> 00:36:23,390
Like I said, views, they're dynamic in that 

613
00:36:23,390 --> 00:36:27,080
it's 1 file, but it would generate different views

614
00:36:27,080 --> 00:36:29,940
based on the variables you actually pass in,

615
00:36:29,940 --> 00:36:32,370
and furthermore, there are a lot of different helper functions

616
00:36:32,370 --> 00:36:34,230
that you can use to help you write your code faster,

617
00:36:34,230 --> 00:36:36,320
which I'll show you in just a second.

618
00:36:36,320 --> 00:36:38,050
Yeah.

619
00:36:38,050 --> 00:36:42,490
>> [Student] So $0 is a controller, right?

620
00:36:42,490 --> 00:36:44,000
That second thing.

621
00:36:44,000 --> 00:36:46,090
The question is is $0 a controller?

622
00:36:46,090 --> 00:36:48,610
$0 is a variable I created right here.

623
00:36:48,610 --> 00:36:51,320
I created a view first. I assigned it to some variable.

624
00:36:51,320 --> 00:36:54,960
Then I passed it into this function, set it as the body of the response.

625
00:36:54,960 --> 00:36:57,260
Does that make sense?

626
00:36:57,260 --> 00:37:02,200
[Student] So is view :: factory, is view like a class

627
00:37:02,200 --> 00:37:06,610
or a library [inaudible] factory function?

628
00:37:06,610 --> 00:37:10,640
The question is about the view :: factory function, 

629
00:37:10,640 --> 00:37:14,020
and basically this is some more object-oriented programming essentially.

630
00:37:14,020 --> 00:37:18,000
View is the view class, and it has a method called "Factory,"

631
00:37:18,000 --> 00:37:24,170
and that's a way to grab the object that's named "blog/index."

632
00:37:24,170 --> 00:37:27,140
And that's some more object-oriented programming stuff

633
00:37:27,140 --> 00:37:33,010
that I'm not going to go into here too much.

634
00:37:33,010 --> 00:37:36,400
Now obviously, we want to create new posts,

635
00:37:36,400 --> 00:37:38,790
but we don't want to have to do it through a database,

636
00:37:38,790 --> 00:37:41,280
so we're going to create a new action for creating a new post,

637
00:37:41,280 --> 00:37:43,050
and there is a lot of stuff we have to do.

638
00:37:43,050 --> 00:37:45,910
>> The first thing we're going to do--let's tackle these things one by one.

639
00:37:45,910 --> 00:37:48,320
The first thing we'll do is we've got to create a form

640
00:37:48,320 --> 00:37:54,460
for inserting a new post,

641
00:37:54,460 --> 00:37:57,360
but I'm also going to add a new action first,

642
00:37:57,360 --> 00:38:01,050
so adding a new action is just as easy as 

643
00:38:01,050 --> 00:38:03,490
adding a new function with your controller,

644
00:38:03,490 --> 00:38:13,710
and for now I'm going to do something very basic,

645
00:38:13,710 --> 00:38:20,850
just grab this view and post it, just display it for you.

646
00:38:20,850 --> 00:38:26,220
And then now I'm going to create a new view file,

647
00:38:26,220 --> 00:38:33,690
and I'm going to start writing some stuff.

648
00:38:33,690 --> 00:38:36,540
What's nice about Kohana is that they provide a lot of different helper functions

649
00:38:36,540 --> 00:38:38,790
for you to write view code more easily,

650
00:38:38,790 --> 00:38:41,970
and 1 of those helper functions or helper modules

651
00:38:41,970 --> 00:38:45,860
is around writing forms.

652
00:38:45,860 --> 00:38:49,460
For writing forms, I don't really have to directly write any HTML myself.

653
00:38:49,460 --> 00:38:51,100
You guys have written HTML forms.

654
00:38:51,100 --> 00:38:54,850
You know how it can be really, really painful and cumbersome to write forms.

655
00:38:54,850 --> 00:38:59,970
It's not fun, so fortunately,

656
00:38:59,970 --> 00:39:04,860
we can basically write a form using Kohana's 

657
00:39:04,860 --> 00:39:11,190
form helper functions to do it for us.

658
00:39:11,190 --> 00:39:17,340
We're going to basically have fields for every single thing we have,

659
00:39:17,340 --> 00:39:23,160
so one for authors and one for the bodies.

660
00:39:23,160 --> 00:39:27,090
We're going to have a label, and we're going to have an input.

661
00:39:37,450 --> 00:39:41,360
>> And then finally, we're going to have a submission.

662
00:39:49,350 --> 00:39:52,230
And as you can see, this is much cleaner to write

663
00:39:52,230 --> 00:39:58,150
than all that messy HTML, which is kind of nice.

664
00:39:58,150 --> 00:40:00,930
Granted, there are other web frameworks that have it even cleaner than that,

665
00:40:00,930 --> 00:40:04,440
but at least this is better than writing the HTML yourself.

666
00:40:09,400 --> 00:40:11,130
Awesome, so this is what you see.

667
00:40:11,130 --> 00:40:13,530
That's kind of messy,

668
00:40:13,530 --> 00:40:19,720
so I'm going to add a line break there

669
00:40:19,720 --> 00:40:21,180
to make that look a little nicer.

670
00:40:21,180 --> 00:40:23,330
Well, of course, it still looks really, really bad, but we're just focused

671
00:40:23,330 --> 00:40:26,050
on the functionality for now and not on the aesthetics.

672
00:40:26,050 --> 00:40:28,010
No time to do everything.

673
00:40:28,010 --> 00:40:30,600
And as you can see, now we have a super basic form,

674
00:40:30,600 --> 00:40:32,080
which is kind of nice.

675
00:40:32,080 --> 00:40:36,730
This code I would say is cleaner than trying to write an HTML form yourself,

676
00:40:36,730 --> 00:40:40,290
so that's nice.

677
00:40:40,290 --> 00:40:42,030
What's next?

678
00:40:42,030 --> 00:40:49,260
Now we need to do things with the action.

679
00:40:49,260 --> 00:40:51,240
Normally when you write HTML forms,

680
00:40:51,240 --> 00:40:54,070
you have to tell it where it's going to submit the form to.

681
00:40:54,070 --> 00:40:56,050
By default in most web frameworks,

682
00:40:56,050 --> 00:40:58,200
it submits to the exact same URL, so the thing is,

683
00:40:58,200 --> 00:41:01,310
if you send a get request to /blog/new,

684
00:41:01,310 --> 00:41:03,240
it should display you the form,

685
00:41:03,240 --> 00:41:06,810
but if you send a post request to /blog/new with the data,

686
00:41:06,810 --> 00:41:10,000
it should actually try to save that post

687
00:41:10,000 --> 00:41:13,300
and do something with it.

688
00:41:20,630 --> 00:41:22,180
>> What we're going to do is

689
00:41:22,180 --> 00:41:25,320
basically all we have to do to check whether it's a post request or a get request

690
00:41:25,320 --> 00:41:29,350
is to check what are the post variables you can set.

691
00:41:29,350 --> 00:41:34,560
And if the post variable is set, then we're going to try and create a new post.

692
00:41:34,560 --> 00:41:38,440
Again, we just do this,

693
00:41:38,440 --> 00:41:41,090
and that creates a new post, and we're literally going to

694
00:41:41,090 --> 00:41:51,150
set its fields like this,

695
00:41:51,150 --> 00:41:55,640
and then we're going to save it.

696
00:41:55,640 --> 00:41:59,200
And then I'm going to redirect

697
00:41:59,200 --> 00:42:07,660
to the index page so they can see our list of posts again.

698
00:42:07,660 --> 00:42:09,620
Let's try that.

699
00:42:09,620 --> 00:42:15,160
I'll say, "Brandon,"

700
00:42:15,160 --> 00:42:18,140
and then submit the post, and if all goes well,

701
00:42:18,140 --> 00:42:21,390
as you can see, it redirected me to the index page,

702
00:42:21,390 --> 00:42:24,140
and if I scroll to the bottom, we have a newly inserted post.

703
00:42:24,140 --> 00:42:26,430
Yay!

704
00:42:26,430 --> 00:42:28,430
Yeah, question.

705
00:42:28,430 --> 00:42:31,760
>> [Student] What if you had entered the exact same thing

706
00:42:31,760 --> 00:42:33,380
you entered before?

707
00:42:33,380 --> 00:42:36,950
Does it check to make sure you haven't duplicated

708
00:42:36,950 --> 00:42:38,810
the same submission?

709
00:42:38,810 --> 00:42:41,660
Be default, no, because by default--

710
00:42:41,660 --> 00:42:46,470
sorry, the question is if you enter in the exact same data in the form

711
00:42:46,470 --> 00:42:50,180
and submit that, will it allow you to insert a duplicate object,

712
00:42:50,180 --> 00:42:52,550
a duplicate entry, essentially?

713
00:42:52,550 --> 00:42:54,070
Right now, yes, it will allow you to do that,

714
00:42:54,070 --> 00:42:58,860
because in databases it's perfectly valid to have completely duplicate rows,

715
00:42:58,860 --> 00:43:02,260
but if that is a concern, then you can add validations, for example, 

716
00:43:02,260 --> 00:43:06,430
to make sure that if this is exactly the same as something that already exists,

717
00:43:06,430 --> 00:43:08,720
then say that it's an invalid object,

718
00:43:08,720 --> 00:43:11,200
and then you can even specify your error message

719
00:43:11,200 --> 00:43:14,390
and say, "Invalid because this already exists" or something like that.

720
00:43:14,390 --> 00:43:22,420
But in this case, I could just create something duplicate.

721
00:43:22,420 --> 00:43:26,010
Now let's try and add some validations.

722
00:43:26,010 --> 00:43:30,400
The problem with this right now is that 

723
00:43:30,400 --> 00:43:34,220
I could literally submit a completely blank post.

724
00:43:34,220 --> 00:43:37,500
I can click this button right now, and there we go.

725
00:43:37,500 --> 00:43:40,290
You can't really see it, but this extra line here

726
00:43:40,290 --> 00:43:43,830
indicates that I literally have a new post.

727
00:43:43,830 --> 00:43:46,050
It just has a blank author and a blank body,

728
00:43:46,050 --> 00:43:48,630
and we don't want to allow people to do that.

729
00:43:48,630 --> 00:43:52,550
This is where validation comes in.

730
00:43:52,550 --> 00:43:57,540
>> I can go to my model object, 

731
00:43:57,540 --> 00:43:59,530
and now I can add a new function that specifies

732
00:43:59,530 --> 00:44:02,000
what validation rules I should add to this model

733
00:44:02,000 --> 00:44:06,840
to make sure that it is valid or to specify what does it mean to be a valid post?

734
00:44:06,840 --> 00:44:10,210
And I want to say it's only a valid post if both the author and body

735
00:44:10,210 --> 00:44:15,150
are not blank, and this is how you do it in Kohana.

736
00:44:15,150 --> 00:44:18,750
You create a new function called "Rules,"

737
00:44:18,750 --> 00:44:20,210
and then you basically return an associative array

738
00:44:20,210 --> 00:44:24,230
that defines the validation rules for this object.

739
00:44:24,230 --> 00:44:27,530
We're going to return the array, and then what we're going to do is

740
00:44:27,530 --> 00:44:32,820
say "author," it goes to an array,

741
00:44:32,820 --> 00:44:37,720
which goes to another array called "not empty."

742
00:44:37,720 --> 00:44:41,480
And then I'm going to say "body."

743
00:44:50,980 --> 00:44:54,120
Okay, and the syntax for this and structure for this

744
00:44:54,120 --> 00:44:56,530
may look a little cumbersome and a little complicated.

745
00:44:56,530 --> 00:44:59,330
If you read the documentation, it's pretty straightforward to figure out,

746
00:44:59,330 --> 00:45:02,500
But essentially this is what you need to do to specify

747
00:45:02,500 --> 00:45:04,130
some validation rules, and there are a lot of different rules

748
00:45:04,130 --> 00:45:06,810
that Kohana will give you for free, like you can add rules to say

749
00:45:06,810 --> 00:45:08,410
it must be at least this length.

750
00:45:08,410 --> 00:45:11,800
Maybe it has to be numeric. Maybe it has to be alpha numeric.

751
00:45:11,800 --> 00:45:14,410
Maybe it has to be at most this length, so on and so forth.

752
00:45:14,410 --> 00:45:17,730
There are a lot of different rules that Kohana provides for you,

753
00:45:17,730 --> 00:45:19,610
and you can go on their website, look at the documentation,

754
00:45:19,610 --> 00:45:23,150
and you can see all the different things that you can do.

755
00:45:23,150 --> 00:45:25,650
>> But this is all I have to do,

756
00:45:25,650 --> 00:45:30,490
and now let's see what happens

757
00:45:30,490 --> 00:45:34,060
if I submit a blank post.

758
00:45:34,060 --> 00:45:36,960
What's going to happen? Oh, no, I get an error.

759
00:45:36,960 --> 00:45:39,440
I get a validation exception.

760
00:45:39,440 --> 00:45:41,070
Well, it's good.

761
00:45:41,070 --> 00:45:43,200
It told me that my model is invalid,

762
00:45:43,200 --> 00:45:45,780
but I don't want to display an exception

763
00:45:45,780 --> 00:45:48,720
to my users when they try to submit something invalid, right?

764
00:45:48,720 --> 00:45:51,560
I want to give them some sort of friendlier error message

765
00:45:51,560 --> 00:45:53,610
when something goes wrong.

766
00:45:53,610 --> 00:46:01,830
What we're going to do is we're going to 

767
00:46:01,830 --> 00:46:04,490
wrap everything in a try catch loop.

768
00:46:04,490 --> 00:46:06,750
Actually, I think this is also something you have not learned yet

769
00:46:06,750 --> 00:46:10,820
in CS50, because C, the programming language C,

770
00:46:10,820 --> 00:46:14,000
doesn't have exceptions, but almost every single other language

771
00:46:14,000 --> 00:46:16,700
has exceptions, so really, really briefly,

772
00:46:16,700 --> 00:46:19,430
an exception is something that a piece of code can 

773
00:46:19,430 --> 00:46:21,430
throw an exception when something goes wrong,

774
00:46:21,430 --> 00:46:23,410
but then maybe some other piece of code higher up

775
00:46:23,410 --> 00:46:25,810
can catch that exception and do something with it.

776
00:46:25,810 --> 00:46:27,710
>> For example, in this case,

777
00:46:27,710 --> 00:46:29,940
the piece of code that's trying to save a model,

778
00:46:29,940 --> 00:46:33,170
it validates the model, and if it says, "Okay, this model is invalid,"

779
00:46:33,170 --> 00:46:36,150
it's going to throw an exception, and this is kind of equivalent to

780
00:46:36,150 --> 00:46:39,870
in C you might return a -1 or something like that.

781
00:46:39,870 --> 00:46:42,320
And then for me, this function, my code

782
00:46:42,320 --> 00:46:46,310
at a higher level, I can try and catch that exception

783
00:46:46,310 --> 00:46:49,330
and basically say, "Okay, if I catch the exception, what am I going to do?"

784
00:46:49,330 --> 00:46:51,570
Or I could choose not to catch that exception and let someone higher up

785
00:46:51,570 --> 00:46:54,400
catch the exception, or if nobody catches it,

786
00:46:54,400 --> 00:46:56,820
then the whole program crashes and says,

787
00:46:56,820 --> 00:46:59,170
"Something went wrong, and I couldn't handle it."

788
00:46:59,170 --> 00:47:04,490
>> But what we do is you wrap a piece of code in a try block,

789
00:47:04,490 --> 00:47:09,030
and then you also add something called a catch block,

790
00:47:09,030 --> 00:47:17,300
which is the sort of code that will try and catch exceptions that may occur.

791
00:47:17,300 --> 00:47:20,430
And so if I catch this particular exception

792
00:47:20,430 --> 00:47:23,110
or invalidation exception, then what I'm going to do is 

793
00:47:23,110 --> 00:47:31,210
I'm going to set the errors--I think that's how I do it--

794
00:47:31,210 --> 00:47:35,370
and I'm going to set the errors to some object.

795
00:47:35,370 --> 00:47:40,920
And then what I'm going to do is if it hits this exception,

796
00:47:40,920 --> 00:47:43,090
it's not going to redirect, and if it doesn't redirect,

797
00:47:43,090 --> 00:47:46,160
it's going to come out of the if blog

798
00:47:46,160 --> 00:47:49,920
and hit this blog/new, which is want I want to do.

799
00:47:49,920 --> 00:47:53,190
If there is an error, then I want to go back to the form

800
00:47:53,190 --> 00:47:55,100
and display those errors.

801
00:47:55,100 --> 00:48:00,780
Now what I want to do is I want to pass in those errors

802
00:48:00,780 --> 00:48:07,010
to the view.

803
00:48:07,010 --> 00:48:10,360
Okay, I think I have the view right here,

804
00:48:10,360 --> 00:48:14,660
and basically I want to display those errors if they exist.

805
00:48:14,660 --> 00:48:19,740
Before I write the HTML for that, I'm going to really quickly

806
00:48:19,740 --> 00:48:21,720
show you what the structure of this errors variable looks like,

807
00:48:21,720 --> 00:48:23,080
and this is a good practice in general.

808
00:48:23,080 --> 00:48:25,070
A lot of times you get something back from some method,

809
00:48:25,070 --> 00:48:27,250
some function in the web framework,

810
00:48:27,250 --> 00:48:29,410
and you don't know what the variable looks like,

811
00:48:29,410 --> 00:48:31,210
so you don't know how to work with it.

812
00:48:31,210 --> 00:48:37,790
I'm going to use a print r method to basically print it out.

813
00:48:37,790 --> 00:48:41,100
>> And as you can see, it tells me it's an associate array,

814
00:48:41,100 --> 00:48:44,880
and you have a key, author, points to this string,

815
00:48:44,880 --> 00:48:47,050
author must not be empty, and another key, body,

816
00:48:47,050 --> 00:48:49,680
points to another string, body must not be empty.

817
00:48:49,680 --> 00:48:52,130
I'm like, okay, cool.

818
00:48:52,130 --> 00:48:56,230
Then I can iterate through the array and print out every single message.

819
00:48:56,230 --> 00:49:02,150
It's basically like an associative array with a bunch of messages.

820
00:49:02,150 --> 00:49:13,500
What I'm going to do is "if errors,"

821
00:49:13,500 --> 00:49:17,140
and I'm going to create an unordered list,

822
00:49:17,140 --> 00:49:20,860
and I'm going to iterate through all the errors.

823
00:49:33,730 --> 00:49:38,710
And this, and now I'm going to try submitting this again,

824
00:49:38,710 --> 00:49:41,200
and let's see what we get.

825
00:49:41,200 --> 00:49:45,370
Now we get this nice list of errors,

826
00:49:45,370 --> 00:49:48,630
and this is still pretty ugly, but this obviously can be formatted to look nice,

827
00:49:48,630 --> 00:49:51,620
but the basic idea is just in a few lines of code,

828
00:49:51,620 --> 00:49:53,720
we were able to validate our model,

829
00:49:53,720 --> 00:49:56,510
make sure that certain fields weren't empty,

830
00:49:56,510 --> 00:49:59,740
and if something went wrong, then return some sort of error message

831
00:49:59,740 --> 00:50:01,760
I could then present back to the user.

832
00:50:01,760 --> 00:50:03,910
You can also customize your validation

833
00:50:03,910 --> 00:50:07,590
so that you can actually have an error message

834
00:50:07,590 --> 00:50:09,620
that is more specific to your application or something like that.

835
00:50:09,620 --> 00:50:14,600
All that is generally customizable.

836
00:50:14,600 --> 00:50:17,150
>> Unfortunately, we're running out of time,

837
00:50:17,150 --> 00:50:20,040
so I'm going to have to cut off the live coding session here.

838
00:50:20,040 --> 00:50:22,980
There are a bunch of other features that I want to demonstrate for you

839
00:50:22,980 --> 00:50:25,650
in this example.

840
00:50:25,650 --> 00:50:27,620
For example, you can add templates to your site,

841
00:50:27,620 --> 00:50:31,110
so maybe there is some sort of HTML code that you want to apply

842
00:50:31,110 --> 00:50:35,190
to every single page in your site, and instead of pasting that

843
00:50:35,190 --> 00:50:40,630
in every single view file you have, which obviously would be a bad practice,

844
00:50:40,630 --> 00:50:43,020
you can basically define these templates,

845
00:50:43,020 --> 00:50:46,660
and then in your controller say, "Okay, I'm using this template."

846
00:50:46,660 --> 00:50:50,130
"Have all my views use this template."

847
00:50:50,130 --> 00:50:52,470
And the one last thing I want to demonstrate to you as well

848
00:50:52,470 --> 00:50:57,800
that we don't have time for is cross-site scripting,

849
00:50:57,800 --> 00:51:01,430
and basically I think you guys have probably seen in CS50--

850
00:51:01,430 --> 00:51:03,770
I think David Malan probably talked about how you can usually inject

851
00:51:03,770 --> 00:51:08,040
JavaScript code into--have you talked about this?

852
00:51:08,040 --> 00:51:10,220
Maybe? Maybe not?

853
00:51:10,220 --> 00:51:12,670
>> But a lot of times you can inject malicious JavaScript code

854
00:51:12,670 --> 00:51:15,630
into someone's database, and if they don't escape that properly,

855
00:51:15,630 --> 00:51:18,280
then when they present that data back to the user,

856
00:51:18,280 --> 00:51:21,310
then it may run some sort of random JavaScript code you don't want to happen,

857
00:51:21,310 --> 00:51:23,050
and I was going to demonstrate how you'd do that within Kohana.

858
00:51:23,050 --> 00:51:25,380
It's actually really, really easy.

859
00:51:25,380 --> 00:51:31,920
I could do it right now in 2 seconds literally.

860
00:51:31,920 --> 00:51:34,560
All you have to do is basically wrap these things

861
00:51:34,560 --> 00:51:46,920
in this thing called HTML entities.

862
00:51:46,920 --> 00:51:51,180
And that will automatically escape all the characters properly

863
00:51:51,180 --> 00:51:54,730
and make sure you don't get this problem.

864
00:51:54,730 --> 00:51:57,220
[Student] You spelled the first test incorrectly.

865
00:51:57,220 --> 00:52:01,030
[Brandon Liu] Oh, oops.

866
00:52:01,030 --> 00:52:06,420
>> Okay, that's all I had to share with you for today.

867
00:52:06,420 --> 00:52:09,930
These slides are going to be posted, but these are generally

868
00:52:09,930 --> 00:52:13,900
the only resources you should really need to get started with Kohana.

869
00:52:13,900 --> 00:52:16,770
You can go to the website. They have a user guide, and they also have an API explorer.

870
00:52:16,770 --> 00:52:20,630
We can explore all the different functions and helper functions they have for you.

871
00:52:20,630 --> 00:52:22,070
They generally have enough information on the website

872
00:52:22,070 --> 00:52:25,310
that you can use to get started and get going with Kohana.

873
00:52:25,310 --> 00:52:30,840
There aren't that many tutorials, I think, for Kohana, outside of

874
00:52:30,840 --> 00:52:33,880
what they have on the website here, so this is probably  your best bet.

875
00:52:33,880 --> 00:52:35,600
But if you want to go with the web framework

876
00:52:35,600 --> 00:52:37,120
and you don't want to have to pick up a new language,

877
00:52:37,120 --> 00:52:39,780
and you want something that is relatively lightweight and has an easy learning curve,

878
00:52:39,780 --> 00:52:41,570
I would definitely suggest Kohana.

879
00:52:41,570 --> 00:52:44,040
That's probably the best offering for that.

880
00:52:44,040 --> 00:52:46,830
The funny thing, though, is if we were using Ruby on Rails,

881
00:52:46,830 --> 00:52:48,550
we could have replicated what we just did

882
00:52:48,550 --> 00:52:51,430
and probably more in under 3 minutes.

883
00:52:51,430 --> 00:52:54,710
No joke, but learning Ruby on Rails takes a lot longer

884
00:52:54,710 --> 00:52:56,780
than it would take to learn Kohana.

885
00:52:56,780 --> 00:52:58,840
It's basically your choice on what you want to choose to learn,

886
00:52:58,840 --> 00:53:01,260
but if you want to get up and running quickly,

887
00:53:01,260 --> 00:53:03,870
Kohana is definitely a very good choice.

888
00:53:03,870 --> 00:53:06,730
>> Any last questions before we end? Yes.

889
00:53:06,730 --> 00:53:08,020
[Student] How would we integrate that

890
00:53:08,020 --> 00:53:13,120
in a CSS framework like you were using when you were instructing?

891
00:53:13,120 --> 00:53:16,700
The question is how would we integrate that with a CSS framework?

892
00:53:16,700 --> 00:53:18,740
What we would probably do is we would probably include

893
00:53:18,740 --> 00:53:21,090
a new folder where we would dump all our CSS files,

894
00:53:21,090 --> 00:53:23,010
and then we'd also add a new template.

895
00:53:23,010 --> 00:53:26,090
In the template we'd include those CSS files

896
00:53:26,090 --> 00:53:28,410
to make sure they're referenced on every single page,

897
00:53:28,410 --> 00:53:32,220
and then when you actually are writing HTML,

898
00:53:32,220 --> 00:53:34,010
you just add appropriate classes and whatnot, 

899
00:53:34,010 --> 00:53:36,100
and for example, when you're using something like the form

900
00:53:36,100 --> 00:53:40,710
helper function, you can add more parameters afterwards

901
00:53:40,710 --> 00:53:42,830
to specify what classes you want to be attached to various things

902
00:53:42,830 --> 00:53:47,820
so they could style it properly, and that's basically how you would go.

903
00:53:47,820 --> 00:53:50,100
>> Any other questions?

904
00:53:50,100 --> 00:53:52,090
Awesome. 

905
00:53:52,090 --> 00:53:58,540
Thank you for your time, and thank you for coming.

906
00:53:58,540 --> 00:54:05,170
I wasn't going to add very much else,

907
00:54:05,170 --> 00:54:08,560
but 1 really quick thing is we don't have a link

908
00:54:08,560 --> 00:54:12,590
to the form.

909
00:54:12,590 --> 00:54:14,310
Really dumb.

910
00:54:14,310 --> 00:54:20,110
Let's add a--actually in the view, blog, index,

911
00:54:20,110 --> 00:54:23,890
let's really quickly add a link that goes to the new page,

912
00:54:23,890 --> 00:54:26,770
the page where we can insert a new post.

913
00:54:26,770 --> 00:54:29,950
We're going to do this.

914
00:54:29,950 --> 00:54:34,020
What's nice is there is this whole group of HTML helper functions

915
00:54:34,020 --> 00:54:37,090
which do different things for you, so you already saw the entities

916
00:54:37,090 --> 00:54:41,980
function here, but they also have a function called "anchor,"

917
00:54:41,980 --> 00:54:45,400
which you can type in blog/new

918
00:54:45,400 --> 00:54:49,550
and say, "Post a new blog."

919
00:54:49,550 --> 00:54:51,850
And it would create that link for you,

920
00:54:51,850 --> 00:54:54,120
and this seems really trivial to do, but this is nice,

921
00:54:54,120 --> 00:54:58,720
because suppose that you are moving your website from 1 domain to another.

922
00:54:58,720 --> 00:55:01,390
And if you just wrote out the URLs yourself,

923
00:55:01,390 --> 00:55:04,350
then you would have to change all the URLs.

924
00:55:04,350 --> 00:55:06,850
Or maybe you moved it from 1 subfolder to another subfolder.

925
00:55:06,850 --> 00:55:08,790
You would have to change all those URLs yourself,

926
00:55:08,790 --> 00:55:12,180
and that's no fun.

927
00:55:12,180 --> 00:55:14,510
You can use this anchor right here,

928
00:55:14,510 --> 00:55:18,950
and you can change the domain or the subfolder prefix

929
00:55:18,950 --> 00:55:20,640
in the configuration file once,

930
00:55:20,640 --> 00:55:22,980
and then it will apply that everywhere, and this is, again,

931
00:55:22,980 --> 00:55:26,930
a great example of do not repeat yourself, DRYing your code out.

932
00:55:26,930 --> 00:55:30,370
Wherever you're repeating yourself, try and extract in some sort of configuration file

933
00:55:30,370 --> 00:55:34,160
or to a different function and have it handle that for you.

934
00:55:34,160 --> 00:55:42,930
>> And the very last thing that I wanted to show you was

935
00:55:42,930 --> 00:55:50,250
suppose we're back at this post, and I had composed some really long essay,

936
00:55:50,250 --> 00:55:52,670
but I forgot to include my author.

937
00:55:52,670 --> 00:55:55,210
Now when I click "Submit Post,"

938
00:55:55,210 --> 00:55:57,270
I just lost everything.

939
00:55:57,270 --> 00:56:00,000
No! Really sad.

940
00:56:00,000 --> 00:56:03,870
So how do you deal with that?

941
00:56:03,870 --> 00:56:06,070
This is what we do.

942
00:56:06,070 --> 00:56:09,340
What we do is here for these input and text area functions,

943
00:56:09,340 --> 00:56:12,700
if we include a second parameter, then the value of that second parameter

944
00:56:12,700 --> 00:56:16,620
is going to be what the field is going to be initially populated with.

945
00:56:16,620 --> 00:56:23,570
What we could do is in our blog controller,

946
00:56:23,570 --> 00:56:25,360
we could bind another variable.

947
00:56:25,360 --> 00:56:27,050
Call it "values" maybe.

948
00:56:27,050 --> 00:56:30,620
And pass in the post array, literally.

949
00:56:30,620 --> 00:56:32,620
That means that if the validation failed,

950
00:56:32,620 --> 00:56:36,570
pass to me the post array that I submitted from the last request,

951
00:56:36,570 --> 00:56:38,420
and that way I can use the values from my last submission

952
00:56:38,420 --> 00:56:44,540
to repopulate the fields.

953
00:56:44,540 --> 00:56:49,600
Now I can do something like values author

954
00:56:49,600 --> 00:56:55,180
and values body, and that way now if I do some random stuff

955
00:56:55,180 --> 00:57:01,490
and click "Submit Post," then it stays there.

956
00:57:01,490 --> 00:57:03,830
But we're going to run into another problem.

957
00:57:03,830 --> 00:57:07,670
That works, but if I go to the page the very first time,

958
00:57:07,670 --> 00:57:09,720
it's going to crash, and that's because the very first time

959
00:57:09,720 --> 00:57:13,730
we go to the page, this post variable has not been defined yet.

960
00:57:13,730 --> 00:57:18,170
It's null. It doesn't exist.

961
00:57:18,170 --> 00:57:21,630
>> And what we want to say is if this key exists,

962
00:57:21,630 --> 00:57:27,750
then return the value of this array,

963
00:57:27,750 --> 00:57:30,450
but if the key doesn't exist, then return a blank string.

964
00:57:30,450 --> 00:57:32,150
That's the functionality we want here.

965
00:57:32,150 --> 00:57:34,690
We want to check if the key exists before trying to access the array,

966
00:57:34,690 --> 00:57:36,580
and fortunately enough,

967
00:57:36,580 --> 00:57:38,570
Kohana also gives us a helper function for that.

968
00:57:38,570 --> 00:57:41,040
They have this whole suite of functions

969
00:57:41,040 --> 00:57:43,660
under the name ARR, short for array,

970
00:57:43,660 --> 00:57:45,800
and they have 1 function called "get,"

971
00:57:45,800 --> 00:57:48,690
and you can pass in the array,

972
00:57:48,690 --> 00:57:50,740
and you can pass in the name of the key.

973
00:57:50,740 --> 00:57:54,330
Then basically what it will do is it will try to get that key,

974
00:57:54,330 --> 00:57:56,470
but if that key doesn't exist in the array,

975
00:57:56,470 --> 00:58:00,900
then it will return blank, or we can also specify a default, I believe,

976
00:58:00,900 --> 00:58:03,500
which is nice.

977
00:58:09,740 --> 00:58:13,150
Now if we do the same thing again,

978
00:58:13,150 --> 00:58:15,970
then you see now it works the first time around,

979
00:58:15,970 --> 00:58:18,080
and again, if we type in some random stuff

980
00:58:18,080 --> 00:58:23,210
and try and submit, then it stays there.

981
00:58:23,210 --> 00:58:31,640
>> And I guess I can also show you how to add a template really quickly.

982
00:58:31,640 --> 00:58:36,140
What we can do first is we can add a new view called "template.php"

983
00:58:36,140 --> 00:58:38,890
within the Views folder,

984
00:58:38,890 --> 00:58:44,730
and what I'm going to do is I'm going to print out something called "content,"

985
00:58:44,730 --> 00:58:49,130
which is going to be my main content.

986
00:58:49,130 --> 00:58:51,380
And maybe at the very bottom I'm going to add, say,

987
00:58:51,380 --> 00:58:53,340
copyright.

988
00:58:53,340 --> 00:58:56,150
[inaudible student question]

989
00:58:56,150 --> 00:58:58,050
[Brandon Liu] Maybe this is a super basic template I want to use.

990
00:58:58,050 --> 00:59:02,840
I want to have a folder with my copyright on every single page,

991
00:59:02,840 --> 00:59:05,560
and now what I'm going to do within my controller

992
00:59:05,560 --> 00:59:07,740
is now instead of saying, "extends Controller"

993
00:59:07,740 --> 00:59:11,870
I'm going to say, "extends Controller_Template,"

994
00:59:11,870 --> 00:59:15,890
and now instead of saying, "response body is equal to this view,"

995
00:59:15,890 --> 00:59:24,110
I'm going to say, "this template content is --"

996
00:59:24,110 --> 00:59:27,690
and I think--do I put an equal sign?

997
00:59:27,690 --> 00:59:32,710
I forget. Yeah, I thought so.

998
00:59:32,710 --> 00:59:37,710
And now I set that content variable to equal the view.

999
00:59:37,710 --> 00:59:40,960
I can do the same here.

1000
00:59:49,620 --> 00:59:57,170
And now if I refresh, you can see now this copyright is added there,

1001
00:59:57,170 --> 01:00:00,350
and just make some random post,

1002
01:00:00,350 --> 01:00:06,760
and then, again, you should see that the copyright is at the very bottom of the page.

1003
01:00:06,760 --> 01:00:10,730
>> Great. That's all I wanted to show you guys.

1004
01:00:10,730 --> 01:00:14,970
[Applause]

1005
01:00:14,970 --> 01:00:18,950
Any questions?

1006
01:00:18,950 --> 01:00:21,000
[CS50.TV]