Django 1.8.19快速入门与核心功能详解

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Django是一个基于Python的高级Web开发框架，由Django Software Foundation维护。本文档是Django官方1.8.19版本的详细介绍，发布日期为2017年6月12日。它提供了全面的指导，从入门到高级主题，涵盖了Django的核心组件、开发过程、安全特性、国际化支持、性能优化以及与其他工具的集成。 **1. Django文档概览** - **获取帮助**: 文档首先介绍了如何获得Django的帮助和支持，包括官方文档、社区论坛和Stack Overflow等资源。 - **第一印象**: 1.2节概述了Django的主要特点，如MVC（模型-视图-模板）架构，强调其简洁和高效的设计。 - **模型层（Model Layer）**: 1.3部分详细解释了Django的ORM（对象关系映射），如何定义和管理数据库模型。 - **视图层（View Layer）**: 1.4节讲解了Django的视图功能，如何处理HTTP请求并响应数据，以及URL routing的概念。 - **模板层（Template Layer）**: 1.5部分涉及Django模板系统，如何利用模板语言来渲染动态网页内容。 - **表单（Forms）**: 1.6部分着重介绍Django的表单处理，包括ModelForm、Form和FormSet的用法。 - **开发过程**: 1.7部分讨论了Django的开发流程，包括项目结构、管理命令和部署选项。 - **后台管理（Admin）**: 1.8介绍了Django内置的Admin界面，用于管理和控制网站内容。 **2. 开始使用Django** - **快速入门指南**: 2.2节提供了一个简明的安装步骤，以便初学者快速搭建环境。 - **编写第一个Django应用**：从2.3到2.10节，通过系列教程指导读者逐步创建一个完整的应用，涉及模型定义、视图编写、模板设计以及数据库迁移等关键步骤。 - **进阶教程**: 2.11介绍了如何为Django贡献代码，如提交第一个patch，培养参与开源项目的技能。 **3. 使用Django的深入内容** - **安装指南**: 3.1部分再次强调了安装和配置Django的具体步骤，确保读者具备基本环境。 - **其他核心功能**：1.13至1.16部分分别探讨了地理定位框架、常用的Web应用工具和Django内核的其他功能，如表单验证、权限管理等。总体来说，这份文档是学习和使用Django的宝贵资源，无论你是初次接触Django还是希望深入了解其高级功能，都能从中找到所需的信息。通过阅读和实践，用户可以掌握这个强大的Web开发框架，并将其应用到实际项目中。

Django Documentation, Release 1.8.19.dev20170530141820

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 just 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.

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 simple 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:

mysite/news/urls.py

from django.conf.urls import url

from . import views

urlpatterns = [

url(r'^articles/([0-9]{4})/$', views.year_archive),

url(r'^articles/([0-9]{4})/([0-9]{2})/$', views.month_archive),

url(r'^articles/([0-9]{4})/([0-9]{2})/([0-9]+)/$', views.article_detail),

]

The code above maps URLs, as simple regular expressions, to the location of Python callback functions (“views”).

The regular expressions use parenthesis to “capture” values from the URLs. When a user requests a page, Django runs

through each pattern, 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 regular expressions are compiled at load

time.

Once one of the regexes matches, Django imports and calls the given view, which is a simple Python function. Each

view gets passed a request object – which contains request metadata – and the values captured in the regex.

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

article_detail(request, '2005', '05', '39323').

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:

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)

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

for non-programmers to use.

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:

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 template 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).

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:

mysite/templates/base.html

{% load staticfiles %}

<html>

<head>

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

</head>

<body>

{% block content %}{% endblock %}

</body>

</html>

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

ﬁll. This makes a site redesign as easy as 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 – simply by 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.

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 makes creating RSS and Atom feeds as easy as writing a small Python class.

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

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

interest!

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 simple, minimal installation that’ll work while you walk through the

introduction.

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/download/ or with your operating system’s package man-

ager.

Django on Jython

If you use Jython (a Python implementation for the Java platform), you’ll need to follow a few additional steps. See

Running Django on Jython for details.

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

Python 3.3.3 (default, Nov 26 2013, 13:33:18)

[GCC 4.8.2] on linux

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

>>>

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Set up a database

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

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

Remove any old versions of Django

If you are upgrading your installation of Django from a previous version, you will need to uninstall the old Django

version before installing the new version.

Install Django

You’ve got three easy options to install Django:

• Install a version of Django provided by your operating system distribution. This is the quickest option for those

who have operating systems that distribute Django.

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

• 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.

Verifying

To verify that Django can be seen by Python, type python from your shell. Then at the Python prompt, try to import

Django:

>>> import django

>>> print(django.get_version())

1.8

You may have another version of Django installed.

That’s it!

That’s it – you can now move onto the tutorial.

Writing your ﬁrst Django app, part 1

Let’s learn by example.

Throughout this tutorial, we’ll walk you through the creation of a basic poll application.

2.3. Writing your ﬁrst Django app, part 1 13

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It’ll consist of two parts:

• A public site that lets people view polls and vote in them.

• An admin site that lets you add, change and delete polls.

We’ll assume you have Django installed already. You can tell Django is installed and which version by running the

following command:

$ python -c "import django; print(django.get_version())"

If Django is installed, you should see the version of your installation. If it isn’t, you’ll get an error telling “No module

named django”.

This tutorial is written for Django 1.8 and Python 3.2 or later. If the Django version doesn’t match, you can refer to

the tutorial for your version of Django by using the version switcher at the bottom right corner of this page, or update

Django to the newest version. If you are still using Python 2.7, you will need to adjust the code samples slightly, as

described in comments.

See How to install Django for advice on how to remove older versions of Django and install a newer one.

Where to get help:

If you’re having trouble going through this tutorial, please post a message to django-users or drop by #django on

irc.freenode.net to chat with other Django users who might be able to help.

Creating a project

If this is your ﬁrst time using Django, you’ll have to take care of some initial setup. Namely, you’ll need to auto-

generate some code that establishes a Django project – a collection of settings for an instance of Django, including

database conﬁguration, Django-speciﬁc options and application-speciﬁc settings.

From the command line, cd into a directory where you’d like to store your code, then run the following command:

$ django-admin startproject mysite

This will create a mysite directory in your current directory. If it didn’t work, see Problems running django-admin.

Note: You’ll need to avoid naming projects after built-in Python or Django components. In particular, this means

you should avoid using names like django (which will conﬂict with Django itself) or test (which conﬂicts with a

built-in Python package).

Where should this code live?

If your background is in plain old PHP (with no use of modern frameworks), you’re probably used to putting code

under the Web server’s document root (in a place such as /var/www). With Django, you don’t do that. It’s not a

good idea to put any of this Python code within your Web server’s document root, because it risks the possibility that

people may be able to view your code over the Web. That’s not good for security.

Put your code in some directory outside of the document root, such as /home/mycode.

Let’s look at what startproject created:

14 Chapter 2. Getting started

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