# Python Django Framework

Django is a high-level Python web framework that encourages rapid development and clean, pragmatic design. It follows the "batteries-included" philosophy, providing everything you need to build a robust web application out of the box.

## Installation

```bash
pip install django
```

## Creating a Project

To start a new Django project:

```bash
django-admin startproject myproject
cd myproject
```

## Running the Server

```bash
python manage.py runserver
```

## Creating an App

A project can contain multiple apps. To create one:

```bash
python manage.py startapp myapp
```

**Important:** You must add `'myapp'` to the `INSTALLED_APPS` list in `myproject/settings.py`.

## Views and URLs

### View (`myapp/views.py`)

A view function takes a web request and returns a web response.

```python
from django.http import HttpResponse

def index(request):
    return HttpResponse("Hello, world!")
```

### URL Configuration (`myapp/urls.py`)

Create a `urls.py` file in your app directory to map URLs to views.

```python
from django.urls import path
from . import views

urlpatterns = [
    path('', views.index, name='index'),
]
```

### Project URLs (`myproject/urls.py`)

Include the app's URLs in the main project configuration.

```python
from django.contrib import admin
from django.urls import include, path

urlpatterns = [
    path('admin/', admin.site.urls),
    path('myapp/', include('myapp.urls')),
]
```

## Templates

Django has a powerful template engine to separate design from Python code.

1.  Create a `templates` directory in your app folder.
2.  Inside that, create a folder with your app name (e.g., `myapp/templates/myapp/`).
3.  Create `index.html`.

```html
<h1>Hello, {{ name }}!</h1>
```

Update the view to render the template:

```python
from django.shortcuts import render

def index(request):
    context = {'name': 'Django'}
    return render(request, 'myapp/index.html', context)
```

## Models (Database)

Define your data structure in `myapp/models.py`. Django uses an ORM (Object-Relational Mapper).

```python
from django.db import models

class Question(models.Model):
    question_text = models.CharField(max_length=200)
    pub_date = models.DateTimeField('date published')
    
    def __str__(self):
        return self.question_text
```

### Migrations

Apply changes to the database schema.

```bash
# Create migration files based on model changes
python manage.py makemigrations

# Apply migrations to the database
python manage.py migrate
```

## Admin Interface

Django provides a built-in admin interface to manage data.

1.  Create a superuser:
    ```bash
    python manage.py createsuperuser
    ```
2.  Register your models in `myapp/admin.py`:

```python
from django.contrib import admin
from .models import Question

admin.site.register(Question)
```

3.  Visit `http://127.0.0.1:8000/admin/` and log in.

[[programming/python/python]]