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Hey, welcome back.

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In the previous video, we set up a Django project and the Django app.

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So we've got the configuration files here in our project directory.

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And this is what we see so far on the front end.

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Now we want to develop the app.

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We want to add code to the app so that we can customize and build what we actually need, which is the

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job application form.

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How do we do that?

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Well, it's common with Django apps to start from the database.

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So a bottom up approach, meaning that you start with a database, the back end, you code the python

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files and then you code the front end, which is the HTML part and CSS and bootstrap.

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So a bottom up approach starting from the database.

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So let's create a database module.

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You'll see.

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I'll explain as we go through this video, I'll explain what a module is.

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So let's stop the server first.

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So to stop the Django app, you want to go to the terminal where the Django app is running.

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So here.

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So put your cursor at the end and press control C, You also see it here.

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So on your keyboard control.

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C And that will stop the server.

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Let's create a model to create a database model you want to go to job application so the app directory

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and go to models.

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Double click that Models.py was created when we ran the Python Manage.py start app command.

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So all these files, including Models.py.

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And so Django added this lines in here, but we need to delete this comment and create our model.

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So a model meaning a class which you can name whatever you like, but I do recommend to name it form.

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And this class should inherit from models dot model.

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So this was imported here models.

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And so this class is a child of the model class, right?

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So a model class now is specialized to specify the columns of.

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The database table.

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Right.

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So our database table will have several fields, several columns, as you know.

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So this will be the output at the end.

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So this is from the previous Flask app that we built in the previous sections.

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But the output will be the same.

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So we'll have a first name input box here, last name, email, available start date and current occupation.

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So when the user enters the data here, they fill in the data they press submit This data will be stored

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in a database table.

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Right?

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So that table should have these columns, first name, last name, email, date and occupation.

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So in here we are designing the database.

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That's what it is meant by model.

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The database model car fields means a character field with a maximum length of 80.

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Make a break line there and you want to duplicate this with Ctrl or command D and change it to last

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name, which is also the same type of field.

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So this field can accept 80 characters in total.

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And then we have the email, this can be an email field, so delete that.

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This is a specialized field to store email addresses.

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Then we have the date.

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This is also another specialized field date field.

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And lastly, occupation.

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This is just another care field.

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Modules that care.

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Fields.

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Max underscore length is again 80.

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And there's one more thing we need to add here, and that is a magic str methods underscore underscore

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str self as an argument.

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I'll explain all this what this method does return f.

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Self dot first name.

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So Dot lost.

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Name.

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What is str.

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Here?

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Well, let me quickly show you that you in a python console.

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So let's say we have a class foo, right?

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Now if Foo doesn't have a string method, when you create an instance of foo like this foo with lowercase

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f and you print that out, you print foo, you don't get any readable output.

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But if you have this class foo again and you have a method str and here you can define what this method

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will return.

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For example, it might return.

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Hello, I am foo right.

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And then if you create an instance again of this new foo class and you print foo, then you will get

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the string representation of that instance.

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Right?

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So this magic method defines what should be printed when a print function is used.

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Or in another case like in this case, this should print out the name of the user or the surname, or

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it will display it in the admin interface when we create an admin interface later on.

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So Django will will display this class, the instance of this class in the form of its salts, for example,

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or another user.

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I hope that's clear.

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Right.

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So now we have a model, but how do we actually apply this model to the database and where is the database?

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Well, the database should be somewhere in here in the project directory.

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DB dot SQLite three.

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Right.

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If you're curious to know what's inside that database.

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So if we have this table or not, I can actually show you that to you.

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Using the DB browser for SQLite program, you can install this program.

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You can search on Google DB browser for SQLite if you're curious, or you can just watch me as I demonstrate

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you what this database has inside.

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So I want to open the database using this button and I want to locate the Django project.

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So there we go.

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That's DB SQLite three.

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Open it.

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And now we don't have any tables.

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Right?

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But we are defining here a form table.

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So how comes that we don't have any tables here?

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Well, that's because we haven't applied any migrations.

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Database migrations yet.

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So what we want to do next is to create migrations.

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I'll explain what migrations are.

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So we want to go to the terminal and type in Python Manage.py make migrations, don't execute it yet.

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So what does this command do now?

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Well, if you go to the job application directory, you will find a migrations directory.

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If you don't have it, don't worry, it will be created when we run this command.

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So until this migrations directory I see this init.py file which is empty.

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Now when I run this command.

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Python manage.py make migrations.

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Some python code will be added to this init method.

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I'll explain what that python code is.

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First, let's run the command, but make sure that in settings settings which is.

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Under my side.

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So my side is the project in settings.py.

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You have job application added already under installed apps just like you see it here.

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So job application is the name of our app job underscore application.

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So close settings and run.

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This commands python manage.py make migrations.

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You should see this output in the command line.

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Now if you go back to job application migrations, you will see this empty file again and also this

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other file initial.py.

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So when we executed this command python manage.py make migrations, what happens is that the form class

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is translated into python code.

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Some other code.

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Right now this code here is like the middleman between the form class and the DB database.

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Right?

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DB dot sqlite three.

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So we still haven't touched the db dot sqlite database.

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So if I go back to DB browser, we still see no tables here.

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So nothing has been changed in the database.

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To apply those migrations we need to execute another command.

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Python manage.py migrate.

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So press enter.

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And now if I go back to DB browser, I want to load the database again to make a refresh.

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So db sqlite three open.

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Now we see 12 tables.

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You see.

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One of those tables.

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So database tables, one of those is job application form.

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And if I expand this, we should see.

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These fields, the columns that we created in Models.py.

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So to wrap it up, what we did is we created this class.

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So the design of our database, the blueprint, then we ran make migrations, Python Manage.py make

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migrations that generated this file with python code and this python code.

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Is then executed when we run python manage.py migrate and that python code alters the database, it

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adds all those tables.

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Now what are these other tables?

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Well, these are the tables that belong to the project, not the app itself.

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So job application form is a table that belongs to the app.

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But these were created because.

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We also have this project, the Django Project.

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So these are like tables which contain configurations about the project.

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Of course, if I go to browse data and I select the job application form table, there are no entries

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here, but these columns, these rows will be populated with data when we create the front end, the

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web page where the user can enter the data their entries.

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So one last thing is that if at a future point you want to add another field to this table, I don't

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recommend you do that now.

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So please don't do it now because you still don't have the proper skills to make such changes.

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But if later on you want to add a new field to your database table, for example, you could add a city

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field here in the form class.

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Then you would have to apply Python manage.py make migrations to create a new file here.

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So that's what creates a new.py file under the migrations folder.

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And then you'd have to run python manage.py migrate to apply those changes to the database table.

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Right.

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I hope that's clear.

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And yeah, that's about creating a database model and applying that model to the actual database.

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So thanks for following.

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See you in the next one.