对于高质量的Web 应用来说，使用简洁、优雅的URL 模式是一个非常值得重视的细节。Django 允许你自由地设计你的URL，不受框架束缚。
\n参见万维网的发明者Berners-Lee 的 Cool URIs don't change，里面有关于为什么URL 应该保持整洁和有意义的卓越论证。
\n为了给一个应用设计URL，你需要创建一个Python 模块，通常被称为**URLconf**(URL configuration)。这个模块是纯粹的Python 代码，包含URL 模式(简单的正则表达式)到Python 函数(你的视图)的简单映射。
\n映射可短可长，随便你。它可以引用其它的映射。而且，因为它是纯粹的Python 代码，它可以动态构造。
\nDjango 还提供根据当前语言翻译URL 的一种方法。更多信息参见 国际化文档。
\n当一个用户请求Django 站点的一个页面，下面是Django 系统决定执行哪个Python 代码使用的算法：
\nDjango determines the root URLconf module to use. Ordinarily,\nthis is the value of the ROOT_URLCONF setting, but if the incoming\nHttpRequest object has a urlconf\nattribute (set by middleware), its value will be used in place of the\nROOT_URLCONF setting.
Django loads that Python module and looks for the variable\nurlpatterns. This should be a Python list of django.urls.path()\nand/or django.urls.re_path() instances.
Django 依次匹配每个URL 模式，在与请求的URL 匹配的第一个模式停下来。
Once one of the URL patterns matches, Django imports and calls the given\nview, which is a simple Python function (or a class-based view). The view gets passed the following\narguments:
\n一个 HttpRequest 实例。
If the matched URL pattern returned no named groups, then the\nmatches from the regular expression are provided as positional arguments.
The keyword arguments are made up of any named parts matched by the\npath expression, overridden by any arguments specified in the optional\nkwargs argument to django.urls.path() or\ndjango.urls.re_path().
If no URL pattern matches, or if an exception is raised during any\npoint in this process, Django invokes an appropriate\nerror-handling view. See Error handling below.
下面是一个简单的 URLconf:
\nfrom django.urls import path\n\nfrom . import views\n\nurlpatterns = [\n path('articles/2003/', views.special_case_2003),\n path('articles/<int:year>/', views.year_archive),\n path('articles/<int:year>/<int:month>/', views.month_archive),\n path('articles/<int:year>/<int:month>/<slug:slug>/', views.article_detail),\n]\n注意：
\nTo capture a value from the URL, use angle brackets.
Captured values can optionally include a converter type. For example, use\n<int:name> to capture an integer parameter. If a converter isn't included,\nany string, excluding a / character, is matched.
There's no need to add a leading slash, because every URL has that. For\nexample, it's articles, not /articles.
一些请求的例子：
\nA request to /articles/2005/03/ would match the third entry in the\nlist. Django would call the function\nviews.month_archive(request, year=2005, month=3).
/articles/2003/ would match the first pattern in the list, not the\nsecond one, because the patterns are tested in order, and the first one\nis the first test to pass. Feel free to exploit the ordering to insert\nspecial cases like this. Here, Django would call the function\nviews.special_case_2003(request)
/articles/2003 would not match any of these patterns, because each\npattern requires that the URL end with a slash.
/articles/2003/03/building-a-django-site/ would match the final\npattern. Django would call the function\nviews.article_detail(request, year=2003, month=3, slug="building-a-django-site").
The following path converters are available by default:
\nstr - Matches any non-empty string, excluding the path separator, '/'.\nThis is the default if a converter isn't included in the expression.
int - Matches zero or any positive integer. Returns an int.
slug - Matches any slug string consisting of ASCII letters or numbers,\nplus the hyphen and underscore characters. For example,\nbuilding-your-1st-django-site.
uuid - Matches a formatted UUID. To prevent multiple URLs from mapping to\nthe same page, dashes must be included and letters must be lowercase. For\nexample, 075194d3-6885-417e-a8a8-6c931e272f00. Returns a\nUUID instance.
path - Matches any non-empty string, including the path separator,\n'/'. This allows you to match against a complete URL path rather than\njust a segment of a URL path as with str.
For more complex matching requirements, you can define your own path converters.
\nA converter is a class that includes the following:
\nA regex class attribute, as a string.
A to_python(self, value) method, which handles converting the matched\nstring into the type that should be passed to the view function. It should\nraise ValueError if it can't convert the given value.
A to_url(self, value) method, which handles converting the Python type\ninto a string to be used in the URL.
例如:
\nclass FourDigitYearConverter:\n regex = '[0-9]{4}'\n\n def to_python(self, value):\n return int(value)\n\n def to_url(self, value):\n return '%04d' % value\nRegister custom converter classes in your URLconf using\nregister_converter():
from django.urls import path, register_converter\n\nfrom . import converters, views\n\nregister_converter(converters.FourDigitYearConverter, 'yyyy')\n\nurlpatterns = [\n path('articles/2003/', views.special_case_2003),\n path('articles/<yyyy:year>/', views.year_archive),\n ...\n]\nIf the paths and converters syntax isn't sufficient for defining your URL\npatterns, you can also use regular expressions. To do so, use\nre_path() instead of path().
In Python regular expressions, the syntax for named regular expression groups\nis (?P<name>pattern), where name is the name of the group and\npattern is some pattern to match.
Here's the example URLconf from earlier, rewritten using regular expressions:
\nfrom django.urls import path, re_path\n\nfrom . import views\n\nurlpatterns = [\n path('articles/2003/', views.special_case_2003),\n re_path(r'^articles/(?P<year>[0-9]{4})/$', views.year_archive),\n re_path(r'^articles/(?P<year>[0-9]{4})/(?P<month>[0-9]{2})/$', views.month_archive),\n re_path(r'^articles/(?P<year>[0-9]{4})/(?P<month>[0-9]{2})/(?P<slug>[\\w-]+)/$', views.article_detail),\n]\nThis accomplishes roughly the same thing as the previous example, except:
\nThe exact URLs that will match are slightly more constrained. For example,\nthe year 10000 will no longer match since the year integers are constrained\nto be exactly four digits long.
Each captured argument is sent to the view as a string, regardless of what\nsort of match the regular expression makes.
When switching from using path() to\nre_path() or vice versa, it's particularly important to be\naware that the type of the view arguments may change, and so you may need to\nadapt your views.
As well as the named group syntax, e.g. (?P<year>[0-9]{4}), you can\nalso use the shorter unnamed group, e.g. ([0-9]{4}).
This usage isn't particularly recommended as it makes it easier to accidentally\nintroduce errors between the intended meaning of a match and the arguments\nof the view.
\nIn either case, using only one style within a given regex is recommended. When\nboth styles are mixed, any unnamed groups are ignored and only named groups are\npassed to the view function.
\nRegular expressions allow nested arguments, and Django will resolve them and\npass them to the view. When reversing, Django will try to fill in all outer\ncaptured arguments, ignoring any nested captured arguments. Consider the\nfollowing URL patterns which optionally take a page argument:
\nfrom django.urls import re_path\n\nurlpatterns = [\n re_path(r'^blog/(page-(\\d+)/)?$', blog_articles), # bad\n re_path(r'^comments/(?:page-(?P<page_number>\\d+)/)?$', comments), # good\n]\nBoth patterns use nested arguments and will resolve: for example,\nblog/page-2/ will result in a match to blog_articles with two\npositional arguments: page-2/ and 2. The second pattern for\ncomments will match comments/page-2/ with keyword argument\npage_number set to 2. The outer argument in this case is a non-capturing\nargument (?:...).
The blog_articles view needs the outermost captured argument to be reversed,\npage-2/ or no arguments in this case, while comments can be reversed\nwith either no arguments or a value for page_number.
Nested captured arguments create a strong coupling between the view arguments\nand the URL as illustrated by blog_articles: the view receives part of the\nURL (page-2/) instead of only the value the view is interested in. This\ncoupling is even more pronounced when reversing, since to reverse the view we\nneed to pass the piece of URL instead of the page number.
As a rule of thumb, only capture the values the view needs to work with and\nuse non-capturing arguments when the regular expression needs an argument but\nthe view ignores it.
\n请求的URL被看做是一个普通的Python 字符串， URLconf在其上查找并匹配。进行匹配时将不包括GET或POST请求方式的参数以及域名。
\n例如， https://www.example.com/myapp/ 请求中，URLconf 将查找 myapp/
在 https://www.example.com/myapp/?page=3 请求中，URLconf 仍将查找 myapp/ 。
URLconf 不检查使用了哪种请求方法。换句话讲，所有的请求方法 —— 即，对同一个URL的无论是 POST请求 、 GET请求 、或 HEAD 请求方法等等 —— 都将路由到相同的函数。
有一个方便的小技巧是指定视图参数的默认值。 下面是一个URLconf 和视图的示例：
\n# URLconf\nfrom django.urls import path\n\nfrom . import views\n\nurlpatterns = [\n path('blog/', views.page),\n path('blog/page<int:num>/', views.page),\n]\n\n# View (in blog/views.py)\ndef page(request, num=1):\n # Output the appropriate page of blog entries, according to num.\n ...\nIn the above example, both URL patterns point to the same view --\nviews.page -- but the first pattern doesn't capture anything from the\nURL. If the first pattern matches, the page() function will use its\ndefault argument for num, 1. If the second pattern matches,\npage() will use whatever num value was captured.
Each regular expression in a urlpatterns is compiled the first time it's\naccessed. This makes the system blazingly fast.
urlpatterns 变量的语法Link to this heading#urlpatterns should be a Python list of path() and/or\nre_path() instances.
When Django can't find a match for the requested URL, or when an exception is\nraised, Django invokes an error-handling view.
\n这些情况发生时使用的视图通过4个变量指定。它们的默认值应该满足大部分项目，但是通过赋值给它们以进一步的自定义也是可以的。
\n完整的细节请参见 自定义错误视图 。
\n这些值得在你的根URLconf 中设置。在其它URLconf 中设置这些变量将不会生效果。
\n它们的值必须是可调用的或者是表示视图的Python 完整导入路径的字符串，可以方便地调用它们来处理错误情况。
\n这些值是：
\nhandler400 -- 查看 django.conf.urls.handler400.
handler403 -- 查看 django.conf.urls.handler403.
handler404 -- 查看 django.conf.urls.handler404.
handler500 -- 查看 django.conf.urls.handler500.
在任何时候，你的 urlpatterns 都可以 "include" 其它URLconf 模块。这实际上将一部分URL 放置于其它URL 下面。
例如，下面是URLconf Django website 自己的URLconf 中一个片段。它包含许多其它URLconf：
\nfrom django.urls import include, path\n\nurlpatterns = [\n # ... snip ...\n path('community/', include('aggregator.urls')),\n path('contact/', include('contact.urls')),\n # ... snip ...\n]\nWhenever Django encounters include(), it chops off\nwhatever part of the URL matched up to that point and sends the remaining\nstring to the included URLconf for further processing.
Another possibility is to include additional URL patterns by using a list of\npath() instances. For example, consider this URLconf:
from django.urls import include, path\n\nfrom apps.main import views as main_views\nfrom credit import views as credit_views\n\nextra_patterns = [\n path('reports/', credit_views.report),\n path('reports/<int:id>/', credit_views.report),\n path('charge/', credit_views.charge),\n]\n\nurlpatterns = [\n path('', main_views.homepage),\n path('help/', include('apps.help.urls')),\n path('credit/', include(extra_patterns)),\n]\n在这个例子中， /credit/reports/ URL将被 credit.views.report() 这个Django 视图处理。
这种方法可以用来去除URLconf 中的冗余，其中某个模式前缀被重复使用。例如，考虑这个URLconf:
\nfrom django.urls import path\nfrom . import views\n\nurlpatterns = [\n path('<page_slug>-<page_id>/history/', views.history),\n path('<page_slug>-<page_id>/edit/', views.edit),\n path('<page_slug>-<page_id>/discuss/', views.discuss),\n path('<page_slug>-<page_id>/permissions/', views.permissions),\n]\n我们可以改进它，通过只声明共同的路径前缀一次并将后面的部分分组:
\nfrom django.urls import include, path\nfrom . import views\n\nurlpatterns = [\n path('<page_slug>-<page_id>/', include([\n path('history/', views.history),\n path('edit/', views.edit),\n path('discuss/', views.discuss),\n path('permissions/', views.permissions),\n ])),\n]\n被包含的URLconf 会收到来自父URLconf 捕获的任何参数，所以下面的例子是合法的:
\n# In settings/urls/main.py\nfrom django.urls import include, path\n\nurlpatterns = [\n path('<username>/blog/', include('foo.urls.blog')),\n]\n\n# In foo/urls/blog.py\nfrom django.urls import path\nfrom . import views\n\nurlpatterns = [\n path('', views.blog.index),\n path('archive/', views.blog.archive),\n]\n在上面的例子中，捕获的 "username" 变量将被如期传递给include()指向的URLconf。
URLconfs have a hook that lets you pass extra arguments to your view functions,\nas a Python dictionary.
\nThe path() function can take an optional third argument\nwhich should be a dictionary of extra keyword arguments to pass to the view\nfunction.
例如:
\nfrom django.urls import path\nfrom . import views\n\nurlpatterns = [\n path('blog/<int:year>/', views.year_archive, {'foo': 'bar'}),\n]\nIn this example, for a request to /blog/2005/, Django will call\nviews.year_archive(request, year=2005, foo='bar').
This technique is used in the\nsyndication framework to pass metadata and\noptions to views.
\n\ninclude()Link to this heading#Similarly, you can pass extra options to include() and\neach line in the included URLconf will be passed the extra options.
For example, these two URLconf sets are functionally identical:
\nSet one:
\n# main.py\nfrom django.urls import include, path\n\nurlpatterns = [\n path('blog/', include('inner'), {'blog_id': 3}),\n]\n\n# inner.py\nfrom django.urls import path\nfrom mysite import views\n\nurlpatterns = [\n path('archive/', views.archive),\n path('about/', views.about),\n]\nSet two:
\n# main.py\nfrom django.urls import include, path\nfrom mysite import views\n\nurlpatterns = [\n path('blog/', include('inner')),\n]\n\n# inner.py\nfrom django.urls import path\n\nurlpatterns = [\n path('archive/', views.archive, {'blog_id': 3}),\n path('about/', views.about, {'blog_id': 3}),\n]\nNote that extra options will always be passed to every line in the included\nURLconf, regardless of whether the line's view actually accepts those options\nas valid. For this reason, this technique is only useful if you're certain that\nevery view in the included URLconf accepts the extra options you're passing.
\nA common need when working on a Django project is the possibility to obtain URLs\nin their final forms either for embedding in generated content (views and assets\nURLs, URLs shown to the user, etc.) or for handling of the navigation flow on\nthe server side (redirections, etc.)
\nIt is strongly desirable to avoid hard-coding these URLs (a laborious,\nnon-scalable and error-prone strategy). Equally dangerous is devising ad-hoc\nmechanisms to generate URLs that are parallel to the design described by the\nURLconf, which can result in the production of URLs that become stale over time.
\nIn other words, what's needed is a DRY mechanism. Among other advantages it\nwould allow evolution of the URL design without having to go over all the\nproject source code to search and replace outdated URLs.
\nThe primary piece of information we have available to get a URL is an\nidentification (e.g. the name) of the view in charge of handling it. Other\npieces of information that necessarily must participate in the lookup of the\nright URL are the types (positional, keyword) and values of the view arguments.
\nDjango provides a solution such that the URL mapper is the only repository of\nthe URL design. You feed it with your URLconf and then it can be used in both\ndirections:
\nStarting with a URL requested by the user/browser, it calls the right Django\nview providing any arguments it might need with their values as extracted from\nthe URL.
Starting with the identification of the corresponding Django view plus the\nvalues of arguments that would be passed to it, obtain the associated URL.
The first one is the usage we've been discussing in the previous sections. The\nsecond one is what is known as reverse resolution of URLs, reverse URL\nmatching, reverse URL lookup, or simply URL reversing.
\nDjango provides tools for performing URL reversing that match the different\nlayers where URLs are needed:
\nIn templates: Using the url template tag.
In Python code: Using the reverse() function.
In higher level code related to handling of URLs of Django model instances:\nThe get_absolute_url() method.
Consider again this URLconf entry:
\nfrom django.urls import path\n\nfrom . import views\n\nurlpatterns = [\n #...\n path('articles/<int:year>/', views.year_archive, name='news-year-archive'),\n #...\n]\nAccording to this design, the URL for the archive corresponding to year nnnn\nis /articles/<nnnn>/.
You can obtain these in template code by using:
\n<a href="{% url 'news-year-archive' 2012 %}">2012 Archive</a>\n{# Or with the year in a template context variable: #}\n<ul>\n{% for yearvar in year_list %}\n<li><a href="{% url 'news-year-archive' yearvar %}">{{ yearvar }} Archive</a></li>\n{% endfor %}\n</ul>\nOr in Python code:
\nfrom django.http import HttpResponseRedirect\nfrom django.urls import reverse\n\ndef redirect_to_year(request):\n # ...\n year = 2006\n # ...\n return HttpResponseRedirect(reverse('news-year-archive', args=(year,)))\nIf, for some reason, it was decided that the URLs where content for yearly\narticle archives are published at should be changed then you would only need to\nchange the entry in the URLconf.
\nIn some scenarios where views are of a generic nature, a many-to-one\nrelationship might exist between URLs and views. For these cases the view name\nisn't a good enough identifier for it when comes the time of reversing\nURLs. Read the next section to know about the solution Django provides for this.
\nIn order to perform URL reversing, you'll need to use named URL patterns\nas done in the examples above. The string used for the URL name can contain any\ncharacters you like. You are not restricted to valid Python names.
\nWhen naming URL patterns, choose names that are unlikely to clash with other\napplications' choice of names. If you call your URL pattern comment\nand another application does the same thing, the URL that\nreverse() finds depends on whichever pattern is last in\nyour project's urlpatterns list.
Putting a prefix on your URL names, perhaps derived from the application\nname (such as myapp-comment instead of comment), decreases the chance\nof collision.
You can deliberately choose the same URL name as another application if you\nwant to override a view. For example, a common use case is to override the\nLoginView. Parts of Django and most\nthird-party apps assume that this view has a URL pattern with the name\nlogin. If you have a custom login view and give its URL the name login,\nreverse() will find your custom view as long as it's in\nurlpatterns after django.contrib.auth.urls is included (if that's\nincluded at all).
You may also use the same name for multiple URL patterns if they differ in\ntheir arguments. In addition to the URL name, reverse()\nmatches the number of arguments and the names of the keyword arguments.
URL namespaces allow you to uniquely reverse named URL patterns even if different applications use the same URL names.\nIt's a good practice for third-party apps to always use namespaced URLs (as we\ndid in the tutorial). Similarly, it also allows you to reverse URLs if multiple\ninstances of an application are deployed. In other words, since multiple\ninstances of a single application will share named URLs, namespaces provide a\nway to tell these named URLs apart.
\nDjango applications that make proper use of URL namespacing can be deployed more\nthan once for a particular site. For example django.contrib.admin has an\nAdminSite class which allows you to easily\ndeploy more than one instance of the admin.\nIn a later example, we'll discuss the idea of deploying the polls application\nfrom the tutorial in two different locations so we can serve the same\nfunctionality to two different audiences (authors and publishers).
A URL namespace comes in two parts, both of which are strings:
\nThis describes the name of the application that is being deployed. Every\ninstance of a single application will have the same application namespace.\nFor example, Django's admin application has the somewhat predictable\napplication namespace of 'admin'.
This identifies a specific instance of an application. Instance namespaces\nshould be unique across your entire project. However, an instance namespace\ncan be the same as the application namespace. This is used to specify a\ndefault instance of an application. For example, the default Django admin\ninstance has an instance namespace of 'admin'.
Namespaced URLs are specified using the ':' operator. For example, the main\nindex page of the admin application is referenced using 'admin:index'. This\nindicates a namespace of 'admin', and a named URL of 'index'.
Namespaces can also be nested. The named URL 'sports:polls:index' would\nlook for a pattern named 'index' in the namespace 'polls' that is itself\ndefined within the top-level namespace 'sports'.
When given a namespaced URL (e.g. 'polls:index') to resolve, Django splits\nthe fully qualified name into parts and then tries the following lookup:
First, Django looks for a matching application namespace (in this\nexample, 'polls'). This will yield a list of instances of that\napplication.
If there is a current application defined, Django finds and returns the URL\nresolver for that instance. The current application can be specified with\nthe current_app argument to the reverse()\nfunction.
The url template tag uses the namespace of the currently resolved\nview as the current application in a\nRequestContext. You can override this default by\nsetting the current application on the request.current_app attribute.
If there is no current application, Django looks for a default\napplication instance. The default application instance is the instance\nthat has an instance namespace matching the application\nnamespace (in this example, an instance of polls called 'polls').
If there is no default application instance, Django will pick the last\ndeployed instance of the application, whatever its instance name may be.
If the provided namespace doesn't match an application namespace in\nstep 1, Django will attempt a direct lookup of the namespace as an\ninstance namespace.
If there are nested namespaces, these steps are repeated for each part of the\nnamespace until only the view name is unresolved. The view name will then be\nresolved into a URL in the namespace that has been found.
\nTo show this resolution strategy in action, consider an example of two instances\nof the polls application from the tutorial: one called 'author-polls'\nand one called 'publisher-polls'. Assume we have enhanced that application\nso that it takes the instance namespace into consideration when creating and\ndisplaying polls.
from django.urls import include, path\n\nurlpatterns = [\n path('author-polls/', include('polls.urls', namespace='author-polls')),\n path('publisher-polls/', include('polls.urls', namespace='publisher-polls')),\n]\nfrom django.urls import path\n\nfrom . import views\n\napp_name = 'polls'\nurlpatterns = [\n path('', views.IndexView.as_view(), name='index'),\n path('<int:pk>/', views.DetailView.as_view(), name='detail'),\n ...\n]\nUsing this setup, the following lookups are possible:
\nIf one of the instances is current - say, if we were rendering the detail page\nin the instance 'author-polls' - 'polls:index' will resolve to the\nindex page of the 'author-polls' instance; i.e. both of the following will\nresult in "/author-polls/".
In the method of a class-based view:
\nreverse('polls:index', current_app=self.request.resolver_match.namespace)\nand in the template:
\n{% url 'polls:index' %}\nIf there is no current instance - say, if we were rendering a page\nsomewhere else on the site - 'polls:index' will resolve to the last\nregistered instance of polls. Since there is no default instance\n(instance namespace of 'polls'), the last instance of polls that is\nregistered will be used. This would be 'publisher-polls' since it's\ndeclared last in the urlpatterns.
'author-polls:index' will always resolve to the index page of the instance\n'author-polls' (and likewise for 'publisher-polls') .
If there were also a default instance - i.e., an instance named 'polls' -\nthe only change from above would be in the case where there is no current\ninstance (the second item in the list above). In this case 'polls:index'\nwould resolve to the index page of the default instance instead of the instance\ndeclared last in urlpatterns.
Application namespaces of included URLconfs can be specified in two ways.
\nFirstly, you can set an app_name attribute in the included URLconf module,\nat the same level as the urlpatterns attribute. You have to pass the actual\nmodule, or a string reference to the module, to include(),\nnot the list of urlpatterns itself.
from django.urls import path\n\nfrom . import views\n\napp_name = 'polls'\nurlpatterns = [\n path('', views.IndexView.as_view(), name='index'),\n path('<int:pk>/', views.DetailView.as_view(), name='detail'),\n ...\n]\nfrom django.urls import include, path\n\nurlpatterns = [\n path('polls/', include('polls.urls')),\n]\nThe URLs defined in polls.urls will have an application namespace polls.
Secondly, you can include an object that contains embedded namespace data. If\nyou include() a list of path() or\nre_path() instances, the URLs contained in that object\nwill be added to the global namespace. However, you can also include() a\n2-tuple containing:
(<list of path()/re_path() instances>, <application namespace>)\n例如:
\nfrom django.urls import include, path\n\nfrom . import views\n\npolls_patterns = ([\n path('', views.IndexView.as_view(), name='index'),\n path('<int:pk>/', views.DetailView.as_view(), name='detail'),\n], 'polls')\n\nurlpatterns = [\n path('polls/', include(polls_patterns)),\n]\nThis will include the nominated URL patterns into the given application\nnamespace.
\nThe instance namespace can be specified using the namespace argument to\ninclude(). If the instance namespace is not specified,\nit will default to the included URLconf's application namespace. This means\nit will also be the default instance for that namespace.