Django 14天从小白到进阶- Day2 搞定url组件

路由系统
models模型
admin
views视图
template模板

路由系统

我们已知，用户从浏览器发出的请求会首先打到django url的路由分发系统这里，然后再到views视图--》models模型--》template模板--》用户浏览器。

换言之，urls.py 文件主载着你整个网站的所有页面&接口的url分配。

正式开讲django的路由语法前，先要知道路由分为以下两种：

静态路由：已经明确定义好的一条路由，比如下例，用户只能在浏览器上输入/articles/2003/ 才能匹配到这条路由，输入任何其它的都匹配不上本条。

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rush:python;gutter:true;">urlpatterns = [
    path('articles/2003/',views.special_case_2003),]

动态路由：定义的只是路由规则，比如只能输入数字、或特定排列、长度的字符等，你不知道用户会具体输入什么，只要符合你的规则即可。比如通过博客园每发篇文章，就会为这篇文章产生一个新的url,这个url肯定不可能是后台程序员手动给你填加的，那他得累死。肯定是他写好规则，比如8662706就代表这个文章编号，这个编号可能是数据库中此文章的id,这个不管，程序员在定义路由时，只需规定，后面用户输入的url必须是数字就行。

Django urls.py 配置

Django 的路由本质上是通过正则表达式来对用户请求的url进行匹配

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rush:python;gutter:true;">from django.urls import re_path
from app01 import views
urlpatterns = [

re_path(r'articles/2003/$',# 静态路由

re_path(r'^articles/(?P[0-9]{4})/$',views.year_archive),# 动态路由

re_path(r'^articles/(?P[0-9]{4})/(?P[0-9]{2})/$',views.month_archive),# 动态路由

re_path(r'^articles/(?P[0-9]{4})/(?P[0-9]{2})/(?P[\w-]+)/$',views.article_detail),# 动态路由

]

以上路由对应views.py视图方法

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rush:python;gutter:true;">def special_case_2003(request):
return HttpResponse("<a href="https://www.jb51.cc/tag/dddd/" target="_blank" class="keywords">dddd</a>")
def year_archive(request,year):

return HttpResponse("year_archive" + str(year))
def month_archive(request,year,month):

return HttpResponse("month_archive %s-%s" %(year,month))
def article_detail(request,month,slug):

return HttpResponse("article_detail %s-%s %s" %(year,slug))

虽然实现了路由匹配，但url中的代码看着很笨拙＋丑陋，不过在黑暗的django 1.0时代，大家只能这么玩。不过解放之神django2.0来啦，带来了路由匹配新玩法。

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rush:python;gutter:true;">from django.urls import path
from . import views
urlpatterns = [

path('articles/2003/',path('articles//',path('articles///',path('articles////',]

先说，实现的功能跟之前用re写的路由一样，但是直观来看，是不是干净了很多？

下面解释语法，我太懒，直接把官网解释copy来啦，

Notes:

Captured values can optionally include a converter type. For example,use teral notranslate"> to capture an integer parameter. If a converter isn’t included,any string,excluding a teral notranslate">/ character,is matched.
There’s no need to add a leading slash,because every URL has that. For example,it’s teral notranslate">articles,not teral notranslate">/articles.

Example requests:

teral notranslate">/articles/2005/03/

teral notranslate">

teral notranslate">/articles/2003/ would match the first pattern in the list,not the second one,because the patterns are tested in order,and the first one is the first test to pass. Feel free to exploit the ordering to insert special cases like this. Here,Django would call the functionteral notranslate">views.special_case_2003(request)
teral notranslate">/articles/2003 would not match any of these patterns,because each pattern requires that the URL end with a slash.
teral notranslate">/articles/2003/03/building-a-django-site/ would match the final pattern. Django would call the functionteral notranslate">.

Path converters

The following path converters are available by default:

teral notranslate">str

ara

teral notranslate">'/'

teral notranslate">int - Matches zero or any positive integer. Returns an int.
teral notranslate">slug - Matches any slug string consisting of ASCII letters or numbers,plus the hyphen and underscore characters. For example,teral notranslate">building-your-1st-django-site.
teral notranslate">uuid - Matches a formatted UUID. To prevent multiple URLs from mapping to the same page,dashes must be included and letters must be lowercase. For example, teral notranslate">075194d3-6885-417e-a8a8-6c931e272f00. Returns a instance.
teral notranslate">path - Matches any non-empty string,including the path separator, teral notranslate">'/'. This allows you to match against a complete URL path rather than just a segment of a URL path as with teral notranslate">str.

上面这些默认自带的converter已经可以满足你大部分的url匹配需求，但有特殊情况不能满足时，你还可以自定义converter哈。

自定义Path Converter

A converter is a class that includes the following:

teral notranslate">regex

A teral notranslate"> method,which handles converting the matched string into the type that should be passed to the view function. It should raise teral notranslate">ValueError if it can’t convert the given value.
A teral notranslate">


For example:
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rush:python;gutter:true;">class FourDigitYearConverter:
    regex = '[0-9]{4}'
def to_python(self,value):
    return int(value)

def to_url(self,value):
    return '%04d' % value</pre>

　　
通过上面的regex参数来看， 其实django 2.0 这个path converter本质上也只是通过对正则表达式进行了封装，使其调用更简单而已。

Register custom converter classes in your URLconf using :

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rush:python;gutter:true;">from django.urls import register_converter,path
from . import converters,views
register_converter(converters.FourDigitYearConverter,'yyyy')
urlpatterns = [

path('articles/2003/',path('articles//',...

]

include 子url

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rush:python;gutter:true;">from django.urls import include,path
urlpatterns = [
... snip ...
path('com<a href="https://www.jb51.cc/tag/munit/" target="_blank" class="keywords">munit</a>y/',include('aggregator.urls')),path('contact/',include('contact.urls')),# ... snip ...
]

django 在匹配url时，只要遇到include()语法，就会把url分成2部分，比如上面代码里的url,只要匹配上community/,就会把整条url丢给include('aggregator.urls')子urls.py。子urls.py负责匹配后面的部分。

减少重复的url

如果url 中出向很多重复的部分，可以按下面的方法聚合

django.urls from apps.main import views as main_views
from credit import views as credit_views

extra_patterns = [
path('reports/',credit_views.report),path('reports//',path('charge/',credit_views.charge),]

urlpatterns = [
path('',main_views.homepage),path('help/',include('apps.help.urls')),path('credit/',include(extra_patterns)),]

in this example,the teral notranslate"> URL will be handled by the teral notranslate"> Django view.

传递额外参数给views

URLconfs have a hook that lets you pass extra arguments to your view functions,as a Python dictionary.

The function can take an optional third argument which should be a dictionary of extra keyword arguments to pass to the view function.

For example:

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rush:python;gutter:true;">from django.urls import path
from . import views
urlpatterns = [

path('blog//',views.year_archive,{'foo': 'bar'}),]

In this example,for a request to teral notranslate">/blog/2005/,Django will call teral notranslate">.

*注：这个功能很少用，知道就行了。

到此，我们就掌握了django url系统的大部分用法，是不是很简单？

Now,it's time to move forward。

Django 14天从小白到进阶- Day2 搞定url组件

路由系统

Django urls.py 配置

Path converters

自定义Path Converter

include 子url

... snip ...

减少重复的url

传递额外参数给views

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