Starting an App:

  • A Django project is organized as a group of individual apps that work together to make the project work as a whole.
  • In the directory that contains manage.py run the startapp command:
1python manage.py startapp code_journals
  • This command startapp appname creates the infrastructure needed to build an app.
  • Look at the project directory now! You should see a new folder called code_journals
  • Open the folder to see the newly created files, including: models.py, admin.py, views.py, etc.
    • We’ll use models to define the data we want to manage in our app.

VS Code Explorer showing the code_journals app folder with newly created files including models.py, admin.py, and views.py

Defining a Model:

  • Look here for a refresher on models. For additional resources click here.
  • Open the file models.py to look at its existing content:

models.py

python
1from django.db import models
2
3# Create your models here.
  • Note we’re invited to create our own model:

models.py open in VS Code showing the blank file with the "Create your models here" comment and a Topic class being defined

  • Here we create a class called Topic.
  • There are two attributes: text and date_added which are created in lines 5 and 6.
    • Two arguments are passed max_length & auto_now_add = True
      • CharField and DateTimeField are data types in the database.
  • The str() method tells Django how to represent data objects based on this model.

How to Activate a Model:

  • To use a model, the app must be added to the list, INSTALLED_APPS, which is stored in the project’s settings.py file.

settings.py

settings.py INSTALLED_APPS list showing code_journals added under the "My apps" section

  • Here we start a project under My apps which includes only code_journals

Migrate the Database:

  • The database needs to be modified to store the kind of data that the model represents.
    • The makemigrations command tells Django to figure out how to modify the database so it can store the data associated with any new models we’ve defined.
1python manage.py makemigrations code_journals
  • Terminal output:
1Migrations for 'code_journals':
2  code_journals\migrations\0001_initial.py
3    - Create model Topic
  • The migrate command has Django modify the database for us.
2python manage.py migrate
  • Terminal output - (Django should confirm that everything worked OK when it applied the migration for code_journals):
1Running migrations:
2  Applying code_journals.0001_initial... OK