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Intro to Django

Setup

Let's create a special development environment. This will separate what we use for class from the rest of your system. It also makes installing python packages easier

python3 -m venv ~/ga-env

now that it's create it, let's start it up:

source ~/ga-env/bin/activate

NOTE: you'll have to run source ~/ga-env/bin/activate every time you create a new terminal window. If you want, you can put this command in ~/.bash_profile or ~/.zshenv depending on whether you're using bash or zsh, respectively

Now let's install Django. This will allow us to create/run django apps:

python -m pip install Django

Let's create a new django project. Go to where on your computer you want your app to be stored and run:

django-admin startproject django_rest_api

This is kind of npm init. Now, go run

cd django_rest_api
python manage.py startapp contacts_api

This will move into your project dir and create an app called contacts_api. A django project can contain many apps. Each app is a logical section of your that is self contained. It's a bit like a controller file in express which contains all routes for one specific model

Now let's get Postgres hooked up to Django. Start your postgres server, open Postgres, and choose any sub database. Once in there, create a sub database that our project will use:

CREATE DATABASE django_contacts;

Now edit django_rest_api/settings.py:

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql',
        'NAME': 'django_contacts',
        'USER': '',
        'PASSWORD': '',
        'HOST': 'localhost'
    }
}

back in terminal run

python -m pip install psycopg2

This installs a driver that allows Django to talk to Postgres. It's a bit like Mongoose.

Now we want to run a migration to set up the tables necessary to get django working. Migrations are python files that run SQL for you, so that you don't have to write it yourself

python manage.py migrate

Now that the db is set up, let's register our contacts_api with django. This is a bit like in express when we require a controller file into server.js

edit django_rest_api/settings.py:

INSTALLED_APPS = [
    'contacts_api', # add this
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
]

Create a model

Now let's create a model. This is similar to migrations, in that it allows us to write python code that will handle the writing of SQL for us.

add to contacts_api/models.py:

class Contact(models.Model):
    name = models.CharField(max_length=32)
    age = models.IntegerField()

Now let's set up a migration that will access our new Contact model and generate the necessary table in Postgres. In the terminal, run:

python manage.py makemigrations contacts_api

This creates the migration, but doesn't execute it. If we want, we can see what sql will be run:

python manage.py sqlmigrate contacts_api 0001

Note, if you create more migrations later on, you'll have to update 0001 to the number of the migration file that was created (check in contacts_api/migrations/ for the appropriate .py file)

Now let's have django run any outstanding migrations that haven't been run yet:

python manage.py migrate

enter into shell

python manage.py shell

in shell

from contacts_api.models import Contact
Contact.objects.all()
c = Contact(name="Matt", age=40)
c.save()
c.id #should return 1
Contact.objects.all()
quit()

in terminal and follow prompts

python manage.py createsuperuser

add to contacts_api/admin.py

from .models import Contact
admin.site.register(Contact)

in terminal

python manage.py runserver

go to http://localhost:8000/admin/

Create api endpoints

install djangorestframework:

python -m pip install djangorestframework

edit django_rest_api/settings.py

INSTALLED_APPS = [
    'rest_framework',  # add this
    'contacts_api',
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
]

create contacts_api/serializers.py

from rest_framework import serializers 
from .models import Contact 

class ContactSerializer(serializers.HyperlinkedModelSerializer):
    class Meta:
        model = Contact
        fields = ('id', 'name', 'age',)

in django_rest_api/urls.py edit

from django.contrib import admin
from django.urls import path
from django.conf.urls import include # add this

urlpatterns = [
    path('', include('contacts_api.urls')), # add this
    path('admin/', admin.site.urls),
]

create contacts_api/urls.py and add

from django.urls import path
from . import views
from rest_framework.routers import DefaultRouter 

urlpatterns = [
    path('api/contacts', views.ContactList.as_view(), name='contact_list'),
    path('api/contacts/<int:pk>', views.ContactDetail.as_view(), name='contact_detail'),
]

set contacts_api/views.py to

from rest_framework import generics
from .serializers import ContactSerializer
from .models import Contact

class ContactList(generics.ListCreateAPIView):
    queryset = Contact.objects.all()
    serializer_class = ContactSerializer

class ContactDetail(generics.RetrieveUpdateDestroyAPIView):
    queryset = Contact.objects.all()
    serializer_class = ContactSerializer

Add CORS

python -m pip install django-cors-headers