4：django url

一个干净的，优雅的URL 方案是一个高质量Web 应用程序的重要细节。

这节我们来看看django是如何做到干净优雅的url的

1：Django如何处理一个请求

1. 通过ROOT_URLCONF决定根URLCONF
2. 调用所有的python模块找到urlpatterns（必须是一个列表）
3. 按照顺序遍历url pattern，知道找到第一个匹配的项
4. 如果找到，调用相应的view函数。。。
5. 如果没找到，调用合适的错误处理函数

简单的url示例

from django.conf.urls import patterns, url, include

urlpatterns = patterns('',
    (r'^articles/2003/$', 'news.views.special_case_2003'),
    (r'^articles/(\d{4})/$', 'news.views.year_archive'),
    (r'^articles/(\d{4})/(\d{2})/$', 'news.views.month_archive'),
    (r'^articles/(\d{4})/(\d{2})/(\d+)/$', 'news.views.article_detail'),
)

• /articles/2003/03/03/会匹配最后一个 pattern. Django 会调用函数news.views.article_detail(request, '2003', '03', '03').

• /articles/2005/3/ 一个也没有匹配上

命名组

格式为(?P<name>pattern)

示例如下

urlpatterns = patterns('',
    (r'^articles/2003/$', 'news.views.special_case_2003'),
    (r'^articles/(?P<year>\d{4})/$', 'news.views.year_archive'),
    (r'^articles/(?P<year>\d{4})/(?P<month>\d{2})/$', 'news.views.month_archive'),
    (r'^articles/(?P<year>\d{4})/(?P<month>\d{2})/(?P<day>\d{2})/$', 'news.views.article_detail'),
)

这个示例和上面的示例是一样的功能，不过不同的地方是：上面的示例传的是位置参数，命名组的参数的关键字参数，这意味着你可以调整参数的位置

• /articles/2005/03/ 会调用函数news.views.month_archive(request, year='2005', month='03'), 而不是news.views.month_archive(request, '2005', '03').

事实上这不是很推荐的写法，不仅使得代码冗长，丑陋，事实上没这个必要，除非你确实想这么做

值得注意的是：

如果存在任何的命名组参数，那么非命名组参数将会被忽略；如果不存在命名组参数，所有的非命名组参数将按照顺序以位置参数的方式传进来

url(regex, view, kwargs=None, name=None, prefix='')

1：如果你有多个view函数的前缀一样，例如

urlpatterns = patterns('',
    (r'^articles/(\d{4})/$', 'news.views.year_archive'),
    (r'^articles/(\d{4})/(\d{2})/$', 'news.views.month_archive'),
    (r'^articles/(\d{4})/(\d{2})/(\d+)/$', 'news.views.article_detail'),
)

你可以这样写

urlpatterns = patterns('news.views',
    (r'^articles/(\d{4})/$', 'year_archive'),
    (r'^articles/(\d{4})/(\d{2})/$', 'month_archive'),
    (r'^articles/(\d{4})/(\d{2})/(\d+)/$', 'article_detail'),
)

2：如果你想引用其他的urlconf文件，你可以使用include这样写

urlpatterns = patterns('',
    # ... snip ...
    (r'^comments/', include('django.contrib.comments.urls')),
    (r'^community/', include('django_website.aggregator.urls')),
    (r'^contact/', include('django_website.contact.urls')),
    (r'^r/', include('django.conf.urls.shortcut')),
    # ... snip ...
)

3：如果你不想引用外部的urlconf，你还可以这样写

extra_patterns = patterns('',
    url(r'^reports/(?P<id>\d+)/$', 'credit.views.report', name='credit-reports'),
    url(r'^charge/$', 'credit.views.charge', name='credit-charge'),
)

urlpatterns = patterns('',
    url(r'^$', 'apps.main.views.homepage', name='site-homepage'),
    (r'^help/', include('apps.help.urls')),
    (r'^credit/', include(extra_patterns)),
)

4：当你给include配置额外参数的时候，这个额外参数会被附加到被include的urlconf文件的每一条url pattern里面

#Set one:
# main.py
urlpatterns = patterns('',
    (r'^blog/', include('inner'), {'blogid': 3}),
)
# inner.py
urlpatterns = patterns('',
    (r'^archive/$', 'mysite.views.archive'),
    (r'^about/$', 'mysite.views.about'),
)
#Set two:
# main.py
urlpatterns = patterns('',
    (r'^blog/', include('inner')),
)
# inner.py
urlpatterns = patterns('',
    (r'^archive/$', 'mysite.views.archive', {'blogid': 3}),
    (r'^about/$', 'mysite.views.about', {'blogid': 3}),
)

这两个set是一样的意思

5：如果两个url pattern被同一个view函数处理，那么当在模板中使用url指令的时候就会发生冲突，这时候url的name参数就可以派上用场了

urlpatterns = patterns('',
    url(r'^archive/(\d{4})/$', archive, name="full-archive"),
    url(r'^archive-summary/(\d{4})/$', archive, {'summary': True}, "arch-summary"),
)

{% url arch-summary 1945 %}
{% url full-archive 2007 %}

需要注意的是，保证你使用的name参数在整个项目里面是唯一的，否则还是有可能发生冲突的

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