Django 4.0.4 教程：从入门到精通PDF文档

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"django 4.0.4 pdf 文件，涵盖了Django软件基金会的官方文档，内容包括Django的各个核心层面，如模型层、视图层、模板层、表单处理、开发流程、管理界面、安全性、国际化与本地化、性能优化、地理框架等，并提供快速安装指南和详尽的新手教程，适合Django初学者和进阶开发者学习使用。" Django是基于Python的一种强大的Web框架，用于构建高效、可扩展的后端应用。在Django 4.0.4的官方文档中，你可以了解到以下重要知识点： 1. **模型层(Model Layer)**：Django的ORM(Object-Relational Mapping)允许开发者用Python类定义数据库结构，这使得数据操作变得简单且直观。模型中定义字段、属性，以及它们与数据库表的关系。 2. **视图层(View Layer)**：视图是Django应用程序中处理请求并返回响应的部分。它们通常负责获取数据、处理逻辑，并调用模板来生成HTML响应。 3. **模板层(Template Layer)**：Django的模板系统允许使用简单的标记语言创建动态HTML，它支持变量替换、控制流和过滤器，使得开发者可以专注于内容布局，而不用关心业务逻辑。 4. **表单(Form)**：Django提供了强大的表单处理功能，可以方便地创建基于模型的表单或者自定义表单，处理HTTP请求中的数据验证和提交。 5. **开发过程(The Development Process)**：Django文档会指导你如何设置开发环境，使用版本控制，以及遵循最佳实践进行开发。 6. **管理界面(Admin Interface)**：Django内置的管理界面可以让你快速创建后台管理系统，用于编辑和管理数据库中的数据。 7. **安全性(Security)**：文档涵盖了Django的安全特性，如CSRF保护、XSS防护、用户认证和权限控制，确保你的应用在开发过程中能遵循安全规范。 8. **国际化与本地化(Internationalization and Localization)**：Django支持多语言，提供了处理翻译文本和时间区域的方法，以便适应全球用户。 9. **性能和优化(Performance and Optimization)**：文档提供了关于如何提高Django应用性能的技巧，包括缓存策略、数据库查询优化等。 10. **地理框架(Geographic Framework)**：Django的地理框架支持地理数据处理，可以处理GIS对象并进行地图显示。 11. **常见Web应用工具(Common Web Application Tools)**：Django提供了许多内置功能，如URL路由、中间件、电子邮件发送等，这些都是构建现代Web应用的基础。 12. **其他核心功能(Other Core Functionalities)**：除了上述功能外，Django还包含诸如测试、静态文件处理、模板标签和过滤器等其他核心特性。此外，文档还包含了快速安装指南，以及一个完整的系列教程，从零开始教你如何编写第一个Django应用，涵盖从创建项目到部署上线的全过程。对于新手来说，这是一个极好的学习资源，可以帮助他们逐步掌握Django的各个方面，从而成为一个熟练的Django开发者。

Django Documentation, Release 4.0.5.dev20220413112808

Listing 3: mysite/news/admin.py

from django.contrib import admin

from . import models

admin.site.register(models.Article)

The philosophy here is that your site is edited by a staﬀ, or a client, or maybe just you – and you don’t want to have to

deal with creating backend interfaces only to manage content.

One typical workﬂow in creating Django apps is to create models and get the admin sites up and running as fast as

possible, so your staﬀ (or clients) can start populating data. Then, develop the way data is presented to the public.

2.1.5 Design your URLs

A clean, elegant URL scheme is an important detail in a high-quality web application. Django encourages beautiful

URL design and doesn’t put any cruft in URLs, like .php or .asp.

To design URLs for an app, you create a Python module called a URLconf . A table of contents for your app, it contains

a mapping between URL patterns and Python callback functions. URLconfs also serve to decouple URLs from Python

code.

Here’s what a URLconf might look like for the Reporter/Article example above:

Listing 4: mysite/news/urls.py

from django.urls import path

from . import views

urlpatterns = [

path('articles/<int:year>/', views.year_archive),

path('articles/<int:year>/<int:month>/', views.month_archive),

path('articles/<int:year>/<int:month>/<int:pk>/', views.article_detail),

]

The code above maps URL paths to Python callback functions (“views”). The path strings use parameter tags to

“capture” values from the URLs. When a user requests a page, Django runs through each path, in order, and stops at

the ﬁrst one that matches the requested URL. (If none of them matches, Django calls a special-case 404 view.) This is

blazingly fast, because the paths are compiled into regular expressions at load time.

Once one of the URL patterns matches, Django calls the given view, which is a Python function. Each view gets passed

a request object – which contains request metadata – and the values captured in the pattern.

For example, if a user requested the URL “/articles/2005/05/39323/”, Django would call the function news.views.

article_detail(request, year=2005, month=5, pk=39323).

10 Chapter 2. Getting started

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2.1.6 Write your views

Each view is responsible for doing one of two things: Returning an HttpResponse object containing the content for

the requested page, or raising an exception such as Http404. The rest is up to you.

Generally, a view retrieves data according to the parameters, loads a template and renders the template with the retrieved

data. Here’s an example view for year_archive from above:

Listing 5: mysite/news/views.py

from django.shortcuts import render

from .models import Article

def year_archive(request, year):

a_list = Article.objects.filter(pub_date__year=year)

context = {'year': year, 'article_list': a_list}

return render(request, 'news/year_archive.html', context)

This example uses Django’s template system, which has several powerful features but strives to stay simple enough for

non-programmers to use.

2.1.7 Design your templates

The code above loads the news/year_archive.html template.

Django has a template search path, which allows you to minimize redundancy among templates. In your Django

settings, you specify a list of directories to check for templates with DIRS. If a template doesn’t exist in the ﬁrst directory,

it checks the second, and so on.

Let’s say the news/year_archive.html template was found. Here’s what that might look like:

Listing 6: mysite/news/templates/news/year_archive.html

{% extends "base.html" %}

{% block title %}Articles for {{ year }}{% endblock %}

{% block content %}

<h1>Articles for {{ year }}</h1>

{% for article in article_list %}

<p>{{ article.headline }}</p>

<p>By {{ article.reporter.full_name }}</p>

<p>Published {{ article.pub_date|date:"F j, Y" }}</p>

{% endfor %}

{% endblock %}

Variables are surrounded by double-curly braces. {{ article.headline }} means “Output the value of the article’s

headline attribute.” But dots aren’t used only for attribute lookup. They also can do dictionary-key lookup, index lookup

and function calls.

Note {{ article.pub_date|date:"F j, Y" }} uses a Unix-style “pipe” (the “|” character). This is called a tem-

plate ﬁlter, and it’s a way to ﬁlter the value of a variable. In this case, the date ﬁlter formats a Python datetime object

in the given format (as found in PHP’s date function).

2.1. Django at a glance 11

Django Documentation, Release 4.0.5.dev20220413112808

You can chain together as many ﬁlters as you’d like. You can write custom template ﬁlters. You can write custom

template tags, which run custom Python code behind the scenes.

Finally, Django uses the concept of “template inheritance”. That’s what the {% extends "base.html" %} does. It

means “First load the template called ‘base’, which has deﬁned a bunch of blocks, and ﬁll the blocks with the following

blocks.” In short, that lets you dramatically cut down on redundancy in templates: each template has to deﬁne only

what’s unique to that template.

Here’s what the “base.html” template, including the use of static ﬁles, might look like:

Listing 7: mysite/templates/base.html

{% load static %}

<html>

<head>

<title>{% block title %}{% endblock %}</title>

</head>

<body>

{% block content %}{% endblock %}

</body>

</html>

Simplistically, it deﬁnes the look-and-feel of the site (with the site’s logo), and provides “holes” for child templates to

ﬁll. This means that a site redesign can be done by changing a single ﬁle – the base template.

It also lets you create multiple versions of a site, with diﬀerent base templates, while reusing child templates. Django’s

creators have used this technique to create strikingly diﬀerent mobile versions of sites by only creating a new base

template.

Note that you don’t have to use Django’s template system if you prefer another system. While Django’s template system

is particularly well-integrated with Django’s model layer, nothing forces you to use it. For that matter, you don’t have

to use Django’s database API, either. You can use another database abstraction layer, you can read XML ﬁles, you can

read ﬁles oﬀ disk, or anything you want. Each piece of Django – models, views, templates – is decoupled from the

next.

2.1.8 This is just the surface

This has been only a quick overview of Django’s functionality. Some more useful features:

• A caching framework that integrates with memcached or other backends.

• A syndication framework that lets you create RSS and Atom feeds by writing a small Python class.

• More attractive automatically-generated admin features – this overview barely scratched the surface.

The next steps are for you to download Django, read the tutorial and join the community. Thanks for your interest!

12 Chapter 2. Getting started

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2.2 Quick install guide

Before you can use Django, you’ll need to get it installed. We have a complete installation guide that covers all the

possibilities; this guide will guide you to a minimal installation that’ll work while you walk through the introduction.

2.2.1 Install Python

Being a Python web framework, Django requires Python. See What Python version can I use with Django? for details.

Python includes a lightweight database called SQLite so you won’t need to set up a database just yet.

Get the latest version of Python at https://www.python.org/downloads/ or with your operating system’s package man-

ager.

You can verify that Python is installed by typing python from your shell; you should see something like:

Python 3.x.y

[GCC 4.x] on linux

Type "help", "copyright", "credits" or "license" for more information.

>>>

2.2.2 Set up a database

This step is only necessary if you’d like to work with a “large” database engine like PostgreSQL, MariaDB, MySQL,

or Oracle. To install such a database, consult the database installation information.

2.2.3 Install Django

You’ve got three options to install Django:

• Install an oﬃcial release. This is the best approach for most users.

• Install a version of Django provided by your operating system distribution.

• Install the latest development version. This option is for enthusiasts who want the latest-and-greatest features

and aren’t afraid of running brand new code. You might encounter new bugs in the development version, but

reporting them helps the development of Django. Also, releases of third-party packages are less likely to be

compatible with the development version than with the latest stable release.

Always refer to the documentation that corresponds to the version of Django you’re using!

If you do either of the ﬁrst two steps, keep an eye out for parts of the documentation marked new in development

version. That phrase ﬂags features that are only available in development versions of Django, and they likely won’t

work with an oﬃcial release.

2.2. Quick install guide 13

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