A cheat sheet for django

Main steps

First step

Install django

pip install django

Second step

Create the project

django-admin startproject PROJECT-NAME

Third step

Move into that project

cd PROJECT-NAME

Fourth step

Create the app wich will run the project

py manage.py startapp APP-NAME

Miscellaneous

Run the shell

py manage.py shell

Run the server

py manage.py runserver

How to create a database (db)

First

Some django app use tables in the db. So before using our own, we need to create the one needed for django.

py manage.py migrate

Second

You need to create models. A models it's a blueprint to tell the db what a table is suppose to look like. A model is a python class, and you create a new class (a new model) for each table you want to add.

A model is created in APP-NAME/models.py like so :

from django.db import models


class NAME_OF_THE_TABLE_1(models.Model):
    NAME_OF_THE_FIRST_FIELD = VALUE_OF_THE_FIRST_FIELD
    NAME_OF_THE_SECOND_FIELD = VALUE_OF_THE_SECOND_FIELD


class NAME_OF_THE_TABLE_2(models.Model):
    NAME_OF_THE_TABLE_1 = models.ForeignKey(NAME_OF_THE_TABLE_1, on_delete=models.CASCADE)
    NAME_OF_THE_FIRST_FIELD = VALUE_OF_THE_FIRST_FIELD
    NAME_OF_THE_SECOND_FIELD = VALUE_OF_THE_SECOND_FIELD

models.ForeignKey(NAME_OF_THE_TABLE_1, on_delete=models.CASCADE) means that the second table is linked with the first one, and if we delete the first one, we also delete this one

For example, we want to create a db wich stores polls, so we want a table for questions, and another one for the answer :

from django.db import models


class Question(models.Model):
    question_text = models.CharField(max_length=200)
    pub_date = models.DateTimeField('date published')


class Choice(models.Model):
    question = models.ForeignKey(Question, on_delete=models.CASCADE)
    choice_text = models.CharField(max_length=200)
    votes = models.IntegerField(default=0)

How to indeed create the tables

When you migrate, django will look in NAME-OF-THE-PROJECT/settings.py and in the variable INSTALLED_APPS. It's a list of all the table wich needs to be created. In order to create our own django create a create a class APP-NAMEConfig inside of APP-NAME/apps.py. It's this file we need to add inside of the variable INSTALLED_APPS. After being added, this list should look like this :

INSTALLED_APPS = [
    'APP-NAME.apps.APP-NAMEConfig',
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
]

Nos that we added a table for our APP-NAME, we need to tell django we changed INSTALLED_APPS :

py manage.py makemigrations APP-NAME

Then we need to apply those changes :

py manage.py migrate

Create a page, urls and templates

How to link to urls

Inside PROJECT-NAME/urls.py :

from django.urls import path, include

urlpatterns = [
    path('admin/', admin.site.urls),
    path('', include("APP-NAME.urls"))
]

Where '' stands for basic url (https://mywbesite/) and 'admin/' for https://mywebsite/admin

Those paths will route to APP-NAME/urls.py and will be get as follow :

from . import views

urlpatterns = [
    path("<int:id>", views.index, name="index"),
    path("", views.home, name="home"),
]

Where int:id mean the url is a number, and run the view.index function. Similarly, empty quotes means base url and run views.home function.

How to display pages

Inside the APP-NAME/views.py :

def name_of_the_views(response, some_parameter):
    # Some stuff
    return render(response, "main/name_of_the_file.html", {"name_of_a_variable_in_html":the_var_itself}) # Where {} can hold variables you want to pass into you html file

Where some_parameter is send by the APP-NAME/urls.py file, in the urlpatterns.

Write html

HTML need to be written into APP-NAME/templates/APP-NAME/. In here you can write every html you want to use.

Specifications

Blocks can be use if the current is used by another HTML file. You can write things in it, and overwrite it in another file :

<!--In base.html-->
<title>{% block name_of_the_block %}My title{% endblock %}</title>

<!--In home.html-->
{% extends 'main/base.html' %}
<!-- Re-use the entire base.html file-->

{% block name_of_the_block %} Another title
<!--Rewrite above the previous block-->
{% endblock %}

---

Variables can be use like so :

<h1>My name is {{variable}}</h1>

Reminders : variables are passed inside the APP-NAME/views.py :

def name_of_the_views(response, some_parameter):
    # Some stuff
    return render(response, "main/name_of_the_file.html", {"name_of_a_variable_in_html":the_var_itself}) # Where {} can hold variables you want to pass into you html file

---

Loop, statement and stuff like so can be used as follow :

<ul>
    {% for item in list %}
    <li>This item : {{item}}</li>
    {% endfor %}
</ul>

Similarly you can do the same with if :

{% if condition %}
<p>This condition is true !</p>
{% else %}
<p>This condition is false</p>
{% endif %}