Django version evolution: from 1.x to 3.x, learn about new features and improvements

Django is a web framework written in Python. Its main features are fast development, easy expansion, high reusability, etc. Since its first launch in 2005, Django has grown into a powerful web development framework.

As time goes by, Django versions are constantly updated. This article will provide an in-depth understanding of Django version evolution, changes from 1.x to 3.x, introduce new features, improvements, and changes that need attention, and provide detailed code examples.

1. Django 1.x version

Django 1.x version is the initial version of Django, including from 1.0.1 to 1.11.29. In this version, Django already has many basic functions, such as:

a. Using ORM for database operations

ORM is a core component of Django. It allows developers to use Python code to operate the database without directly using SQL statements. ORM makes operations easier and more intuitive. A simple example:

from django.db import models

class Blog(models.Model):
    name = models.CharField(max_length=100)
    tagline = models.TextField()

class Author(models.Model):
    name = models.CharField(max_length=50)
    email = models.EmailField()

class Entry(models.Model):
    blog = models.ForeignKey(Blog, on_delete=models.CASCADE)
    headline = models.CharField(max_length=255)
    body_text = models.TextField()
    pub_date = models.DateTimeField()
    mod_date = models.DateTimeField()
    authors = models.ManyToManyField(Author)
    n_comments = models.IntegerField()
    n_pingbacks = models.IntegerField()
    rating = models.IntegerField()

In the above example, we defined three data models, Blog, Author and Entry, which all inherit from models.Model. The attributes of these classes correspond to the fields in the database table. For example, the Blog class has two fields: name and tagline, which are used to store the string type blog name and slogan respectively. While defining the data model, Django will automatically generate the corresponding database tables, add, delete, modify and query operations, and ORM API.

b. Automatically manage URLs

In Django 1.x version, we only need to write the view function to handle HTTP requests, and do not need to manually manage URLs ourselves. Django will automatically map the request to the corresponding view function based on the configured URL routing. For example:

from django.conf.urls import url
from . import views

urlpatterns = [
    url(r'^$', views.index, name='index'),
    url(r'^(?P<question_id>[0-9]+)/$', views.detail, name='detail'),
    url(r'^(?P<question_id>[0-9]+)/results/$', views.results, name='results'),
    url(r'^(?P<question_id>[0-9]+)/vote/$', views.vote, name='vote'),
]

In the above example, we defined four URL routes, including the homepage, question details page, voting results page and voting function page. For each URL route, we specify the corresponding processing function. Django will automatically match the requested URL with the route, thereby realizing the function of automatically managing URLs.

c. Built-in admin background management system

Django’s admin background management system is a very powerful function. Through this background management system, we can easily add, delete, modify and check the database. The admin background management system in Django 1.x version already has many basic functions, such as automatically generating admin sites, managing data models, displaying customized lists, filters and forms, etc.

2. Django 2.x version

Django 2.x version includes from 2.0.0 to 2.2.24, which makes some major improvements to Django.

a. Introduction of ASGI

In Django 2.x version, the ASGI (Asynchronous Server Gateway Interface) protocol was introduced. ASGI is a protocol designed for asynchronous web servers, which allows developers to write asynchronous web applications. In this way, we can better meet the needs of asynchronous programming, such as websockets, real-time communication, time-consuming tasks, etc.

async def application(scope, receive, send):
    assert scope['type'] == 'http'

    await send({
        'type': 'http.response.start',
        'status': 200,
        'headers': [
            [b'content-type', b'text/plain'],
        ]
    })
    await send({
        'type': 'http.response.body',
        'body': b'Hello, world!',
    })

The above code example uses ASGI to write a simple web application. First, define an application asynchronous function, which accepts three parameters: scope, receive and send. These parameters are fixed and agreed upon by the ASGI protocol. Among them, scope represents the context of the request, including the request type, path, query string, etc.; receive represents the method of receiving the request, constructing a dictionary to represent the request header, response code, etc.; send represents returning a response to the client. .

b. Removed Python 2.x compatibility

In the Django 2.x version, Python 2.x compatibility has been removed, and Python from third-party libraries is no longer supported. 2.x version. This means that developers need to use Python 3.x to develop Django applications.

In addition, Django 2.x version has also made some other improvements and optimizations, such as:

• Added new HTTP status codes and exceptions;
• Added better password security mechanism;
• Supports better testing and introduces a new testing framework.

3. Django 3.x version

Django 3.x version is the latest version currently, including from 3.0.0 to 3.2.5. It further enhances its functionality and performance based on version 2.x.

a. Support path parameters

In Django 3.x version, Path Converters, that is, support for path parameters, was introduced. This new feature is very useful for developing RESTful APIs and can provide a more flexible matching method for URLs.

from django.urls import path

def greet(request, name):
    return HttpResponse(f'Hello, {name}!')

urlpatterns = [
    path('greet/<name>/', greet),
    ...
]

In the above example, we defined a path parameter name. Any value in the request path can be populated into the name parameter and represented as such when processing the view.

b. Replace UnicodeSlugify

In Django 3.x version, UnicodeSlugify is no longer used to replace its default Slugify. UnicodeSlugify is a third-party library that allows developers to work with more languages ​​and character sets. Instead of UnicodeSlugify, a new Slugify algorithm was designed for Django that is more standardized, more localized, more comprehensive, more scalable and more secure.

c. Optimize database query

In Django 3.x version, the database query method is further optimized. For example, when the application starts, Django caches the metadata for all database queries. This can reduce the number of lookups of the table structure and improve the response speed of the application.

In addition, Django 3.x version also adds many other new features and improvements, such as:

• New middlewares that support multiple reading databases;
• Significantly optimize the generation of query plans;
• Added support for dynamically changing aggregation and grouping queries;
• Added support for asynchronous email and HTTP requests;

This article briefly explains the changes in the evolution from Django1.x to Django 3.x. These changes bring better performance, better development efficiency, and better ease of use. As an MVC framework, I believe Django will become more and more perfect.

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