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Welcome back, everyone, to this lecture on how Django works.

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We're going to be discussing the key ideas behind how the Django framework actually operates and works.

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This is also going to lead to a nice roadmap of our learning journey for the rest of the course.

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So the key features of jangle fall under what is usually called a model template view structure.

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So you have your model, which connects to the actual database, your template which connects to the

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user browser and then your view, which is kind of a connection between the model and the template.

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And in general terms, there's going to be a couple of features that allows us to follow this MTV structure

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and that is an object relational mapper or 000rpm.

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The Python models themselves written with Django, the URLs and views, and then the templates.

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So let's see how this actually plays out.

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If we're trying to connect information from a database somewhere, such as a database hosted on Leno

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to a user browser.

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So what we have here is the connection we're trying to do, get information from the database all the

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way to the user browser and then clearly there's going to be some interactivity.

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And you can think that every web application at its core is doing something similar to this.

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It's transferring information from a database to a user.

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And then the user can update or transfer information back to the database, and information can be videos,

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pictures, text activities, cetera.

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OK, so let's start backwards from the user browser, and we're going to be exploring this in terms

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of actual Django framework specifics.

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So your user browser is going to end up receiving what's known as a template, and the template itself

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is going to be an HTML file, so the template is HTML.

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But keep in mind, a dot HTML file can then link to things like a CSV file or a JavaScript file, so

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you can understand the template as what your browser is directly reading for information of what to

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display to the user.

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Now, how do we actually end up connecting the template to the database?

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Each HTML, CSS and JavaScript aren't really going to be stored as far as things that can be manipulated

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by the user.

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Instead, we're going to use ginger templating and note might use their of two curly sets of brackets

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because that's the sort of syntax you're going to be seeing when we actually discover how to work with

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ginger templating.

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But ginger itself allows us to insert information directly from a python file into that template.

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So this later connects to the actual Python file that's using the Django Library or Django framework.

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So we end up doing is we create a view component, and this is typically going to be something called

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viewport pie is the python file, and this python file is essentially a list of functions and the use

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of decorators.

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It's going to allow us to inject information into that template directly from Python, which this allows

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us to use all different types of Python libraries to do any sort of analysis or manipulation with the

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data of a Python library, and then inject that information directly into the template in a form that

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the user browser can then understand.

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The other thing to note is that this view works in concert with some URL routing.

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Typically, this is going to be another Python file, often called URLs that pie.

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And this just tells which view goes to which URL route.

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So one view may be associated to my website dot com forward slash stuff, and maybe another view goes

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to another subdomain like my website dot com for slash users.

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So you can see here it's going to be interactivity between the views and which route they should take,

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which connects them to a specific template which is then shown to the user browser.

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And keep in mind, right now I'm showing everything kind of going towards the user browser, but a lot

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of this will have back and forth interconnectivity.

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So where does the actual information connect to the database?

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Well, the view information itself is often linked to a model, and models are going to be a subset

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of the jingo framework that is actually a python representation of a database and database tables.

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So models, it's going to be yet another Python file again, often called models, not pie.

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And this is using Django models, which are essentially python classes where you have these different

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attributes inside the class that end up representing different columns within a table within a database.

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So that's actually going to end up linking directly to your database.

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And what's really nice about Django is by just working with the models file often Django, you pretty

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much don't have to worry about all the sequel and database management that's happening behind the scenes.

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That's what makes Django so powerful is that even though this looks really complex, you just end up

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dealing with a couple of Python files using Python code, and Django itself is doing all the heavy lifting

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for you on the back end by actually setting stuff up with a sequel database, making sure you are all

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routings, connecting to your views and so on.

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So this is the main pathway that we would actually follow to get information from a database to the

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user browser.

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We have a database typically stored in something like sequel and then that is directly linked to a model's

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file that's using the Django framework, and that itself is a Python file.

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And then we can connect those models to different views, and those views through a URL routing configuration

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are then allowing us to insert information into a template that the user can then see in their browser.

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Now, if you're more familiar with terms like what's happening on the client side versus the server

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side, you can think of the template as the client side because it's actually happening on the user's

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computer.

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They're actually seeing the HTML, the CSC, JavaScript and then what's inserted through ginger, which

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eventually just becomes normal HTML on the user browser side and then everything else is happening on

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the server side.

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So everything that really has to do with import Django and do something is happening on the server side

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of the URL, routing the views and the models and eventually further back the database, which is storing

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all the information that's connected through the models.

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So if we think about this back in terms of model template view structure, we have the Model S., which

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is kind of this model's connection to a database.

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You have the template side of things which is going to be your HTML template that is using gender templating

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to actually then connect to the view section, which you can kind of think of as the view that's actually

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working with the data connecting to your routing.

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And it's the connection between the model on the very back and the things versus the template on the

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front and the things for the actual client side.

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This is where you get that model view template structure.

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And again, I mentioned that this was all diagram showing a one way connection to the database of the

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user browser.

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But keep in mind that the models and database those are actually going to have interconnectivity.

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So you can update models which and updates your sequel database.

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And you should also keep in mind that you can have many more Python files for application logic so you

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can have something like that pie, which maybe does some machine learning logic, and you just connect

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that through import to your final viewport pie file.

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So there's going to be lots of interconnectivity between models having logic applied to them in Python

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and then sending that to The View.

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Or maybe you just send the models directly to the View, or maybe you're using some other application

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logic within your Python file, cetera.

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Main idea here being is that this is where you can really expand the flexibility of Python by adding

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in as many Python scripts as you want and performing many different types of manipulation, analysis,

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comprehension of the data, et cetera, through Python applications.

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And eventually, you send that information to the view that pie file, which itself is connected with

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URL routing to eventually serve that information through Jinja templating, which can then be sent to

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the user.

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And obviously, this goes both ways.

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The user can then update information, which is then sent to the View, which updates the model, which

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updates the database.

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So it's not just one way the user can update, as well as Django and Python reporting back to the user

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what the current status of things in the database is.

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All right.

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So the jingo structure will also have many more features not actually shown in that simple MTV diagram,

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such as authentication and administration access.

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So something we didn't really talk about here is the fact that Django comes with tools to make sure

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that user has to be authenticated in order to view certain parts of a website.

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Or maybe there's also administration access that comes already built in of Django, which allows a super

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user to just directly jump to the database and see individual entries inside that actual SQL database.

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And you'll see how awesome this feature is when it's pretty much it's just created for you automatically

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from the Django framework.

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So what are the actual jingo drawbacks, of course, right now, everything's super great.

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Well, keep in mind that jingo itself is heavily reliant on this idea of that model, which connects

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to the database and the model is this Python or Django representation of a table in that database?

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What is really nice about this is that it makes it very easy to work with querying the data, but it

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does add the requirements of understanding models pretty well and then setting them up for views.

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So this is sometimes the steeper part of the learning curve.

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Is that Django, in order to do a lot of the heavy lifting for you by setting up your SQL database,

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those require the user itself to have some knowledge of how these models work within Django.

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Now, of course, the purpose of this course itself is to make that easy for you.

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So I wouldn't worry too much about the learning curve as a drawback.

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Just keep in mind that there is this heavy reliance on the model structure, but I think when you get

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more and more familiar of Django, you'll actually like this idea of having everything going through

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the model because it applies a very specific workflow to the website or web application itself.

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So what we can do now is continue our understanding of jingo by beginning to learn about these key components

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separately and then slowly adding on complexity to a fully functioning website.

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OK.

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Thanks, and I'll see you at the next lecture.