1. Django概述

时间：2021-06-11 15:35:50

1.1 设计模型

Django，但它附带了一个你可以用python代码描述数据库布局的对象关系映射器。

数据模型语法提供了许多丰富的方法来展现你的模型——到目前为止，它解决了多年来数据库模式问题。

简单的例子

#mysite/news/models.py

from django.db import models

class Reporter(models.Model):

    full_name = models.CharField(max_length=70)

    def __str__(self):

        return self.full_name

class Article(models.Model):

    pub_date = models.DateField()

    headline = models.CharField(max_length=200)

    content = models.TextField()

    reporter = models.ForeignKey(Reporter)

    def __str__(self):

        return self.headline

1.2创建数据库

python manage.py migrate
migrate命令会查找所有可用的模型然后在你的数据库中，创建还不存在的数据库表。

1.3使用API

使用一个便捷且功能丰富的Python API来访问你的数据。这些API是即时创建的，不需要代码生成：
# 导入模型

>>> from news.models import Reporter, Article

# 查看实例.

>>> Reporter.objects.all()

[]

# 创建一个实例.

>>> r = Reporter(full_name='John Smith')

# 保存对象.

>>> r.save()

# 查看Id.

>>> r.id

1

# 显示数据库的信息.

>>> Reporter.objects.all()

[<Reporter: John Smith>]

# Fields are represented as attributes on the Python object.

>>> r.full_name

'John Smith'

# Django provides a rich database lookup API.

>>> Reporter.objects.get(id=1)

<Reporter: John Smith>

>>> Reporter.objects.get(full_name__startswith='John')

<Reporter: John Smith>

>>> Reporter.objects.get(full_name__contains='mith')

<Reporter: John Smith>

>>> Reporter.objects.get(id=2)

Traceback (most recent call last):

    ...

DoesNotExist: Reporter matching query does not exist.

# Create an article.

>>> from datetime import date

>>> a = Article(pub_date=date.today(), headline='Django is cool',

...     content='Yeah.', reporter=r)

>>> a.save()

# Now the article is in the database.

>>> Article.objects.all()

[<Article: Django is cool>]

# Article objects get API access to related Reporter objects.

>>> r = a.reporter

>>> r.full_name

'John Smith'

# And vice versa: Reporter objects get API access to Article objects.

>>> r.article_set.all()

[<Article: Django is cool>]

# The API follows relationships as far as you need, performing efficient

# JOINs for you behind the scenes.

# This finds all articles by a reporter whose name starts with "John".

>>> Article.objects.filter(reporter__full_name__startswith='John')

[<Article: Django is cool>]

# Change an object by altering its attributes and calling save().

>>> r.full_name = 'Billy Goat'

>>> r.save()

# Delete an object with delete().

>>> r.delete()

1.3在admin site中注册模型

一旦你的模型定义完毕之后，Django能自动创建一个专业的、可以用于生产环境的 管理界面 – 可以让认证的用户添加、修改和删除对象的一个站点。只需简单地在admin site中注册你的模型即可：

#mysite/news/admin.py

from django.contrib import admin

from . import models

admin.site.register(models.Article

1.4设计URLs

设计urls并包含映射

#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),

]

1.5编写视图

返回一个包含请求的页面内容的 HttpResponse对象， 或抛出一个异常如Http404，

通常，视图会根据参数检索数据，加载模版，使用数据渲染模版

#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)

1.6设计模版

Django可以通过DIRS指定一个查找模版的列表

使用base.html ，进行渲染

Total:  概述的内容大概就是这样子了，之前简单的了解一点Django，感觉还是很方便的，看了廖学费的webapp教程，讲解太少，怪自己太愚也没怎么看懂。Django文档写的很详细，至少第一节是这样子的，相比之下更简单方便的多，特别是对于数据库的创建和引用，就这样吧。It is time to study django. Come on !

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