from django.conf.urls import url# 使用url关键字
urlpatterns = [url('article-(\d+).html',views.article),url('article-(?P<article_id>\d+).html',views.article)
]
# url请求地址为：http://127.0.0.1:8000/article-1.html

Django1的url支持正则匹配：
'article-(\d+).html'：使用正则表达式的分组匹配来获取URL中的参数，并以位置参数形式传递给视图article。
'article-(?P<article_id>\d+).html'：使用正则表达式的分组命名匹配来获取URL中的参数，并以关键字参数的形式传递给视图article。分组命名正则表达式组的语法是：(?P<name>pattern)，其中name是组的名称(视图中的关键字参数必须跟组名一致)，pattern是正则表达式。

from django.urls import path# 使用path关键字
urlpatterns = [path('article-<int:article_id>.html',views.article),
]
# url请求地址为：http://127.0.0.1:8000/article-1.html

class Date:regex = '^0?[1-9]$|^1[0-2]$'def to_python(self, value):# 可以写你的逻辑，对匹配到的字符串进行处理value = '2019/' + valuereturn valuedef to_url(self, value):return '%2s' % value# 在主路由下导入,生成转换器
from django.urls import register_converterregister_converter(Date,'date')path('full-year/<date:full_year>/',views.full_year, name="full_year")

from django.urls import re_path
这里的re_path的用法跟Django1的url用法视完全一样的，匹配正则。urlpatterns = [path('articles/2003/', views.special_case_2003),  # Django2的写法re_path('articles/(?P<year>[0-9]{4})/', views.year_archive),  # 兼容Django1的写法re_path('articles/(?P<year>[0-9]{4})/(?P<month>[0-9]{2})/', views.month_archive),re_path('articles/(?P<year>[0-9]{4})/(?P<month>[0-9]{2})/(?P<slug>[^/]+)/', views.article_detail),
]

创建两个app，每个app都创建一个urls.py# 项目的urls.py
from django.conf.urls import url, include
from app01 import urls as app01_urls
from app02 import urls as app02_urlsurlpatterns = [# 二级路由系统url(r'^app01/', include(app01_urls)),url(r'^app02/', include(app02_urls)),
]# app01的urls.py
from django.conf.urls import url
from app01 import viewsurlpatterns = [url(r'^book/$', views.book_list),url(r'^book/(?P<yyyy>[0-9]{4})/$', views.book),url(r'^blog/$', views.blog),url(r'^blog/(?P<num>\d+)/$', views.blog),
]# app02的urls.py
from django.conf.urls import url
from app02 import viewsurlpatterns = [url(r'^index/$', views.index),url(r'^home/$', views.home),
]解析：在浏览器输入http://127.0.0.1:8000/app02/home/
首先会拿着app02/home/去项目的urls中匹配，找到url(r'^app02/', include(app02_urls)),
看到include，就拿着home/去app02的urls中匹配，找到url(r'^home/$', views.home),就访问home页面。

# 项目的urls.py
from django.conf.urls import url, include
from app02 import urls as app02_urlsurlpatterns = [# 二级路由系统url(r'^app02/', include(app02_urls)),
]# app02的urls.py
from django.conf.urls import url
from app02 import viewsurlpatterns = [url(r'^login/$', views.login),url(r'^index/$', views.index, name='myindex'),
]# views.py
from django.shortcuts import render, redirect, HttpResponse
from django.urls import reverse  # 导入reverse反向解析出地址def login(request):if request.method == 'POST':username = request.POST.get('username')pwd = request.POST.get('pwd')ret = UserInfo.objects.filter(username=username, pwd=pwd)if ret:return redirect(reverse('myindex'))  # reverse反向解析出url地址：/app02/index/return render(request, 'login.html')def index(request):return HttpResponse('index')解析：在浏览器输入http://127.0.0.1:8000/app02/login/，进入登录界面，
登录成功后，redirect(reverse('myindex'))，reverse会根据别名myindex自动解析出index的具体路径(http://127.0.0.1:8000/app02/index/)，
而且无论index的具体路由怎么改变，reverse('myindex')总是能解析出具体的url。注意：当url需要参数时：1.如果index需要传位置参数：
urlpatterns = [url(r'^index/(\d+)/$', views.index, name='myindex'),
]return redirect(reverse('myindex', args=('2018',)))2.如果index需要传关键字参数：
urlpatterns = [url(r'^index/(?P<year>\d+)/$', views.index, name='myindex'),
]return redirect(reverse('myindex', kwargs={'year': '2019'}))# 在HTML模板中使用
无参数：<a href="{% url 'myindex' %}">myindex</a>有参数：<a href="{% url 'myindex' '2018' %}">myindex</a>

# 项目中的urls.py
from django.conf.urls import url, includeurlpatterns = [url(r'^app01/', include('app01.urls', namespace='app01')),url(r'^app02/', include('app02.urls', namespace='app02')),
]# app01中的urls.py
from django.conf.urls import url
from app01 import viewsurlpatterns = [url(r'^index/(?P<year>\d+)/$', views.index, name='myindex'),
]# app02中的urls.py
from django.conf.urls import url
from app02 import viewsurlpatterns = [url(r'^index/(?P<year>\d+)/$', views.index, name='myindex'),
]现在，两个app中url的别名重复了，反转URL的时候就可以通过命名空间的名称得到我当前的URL。
语法：
'命名空间名称:URL名称'# 在HTML模板中使用：
<a href="{% url 'app01:myindex' '2018' %}">app01 myindex</a>
<a href="{% url 'app02:myindex' '2019' %}">app02 myindex</a># 在views中的函数中使用
v = reverse('app01:myindex', kwargs={'year':2018})
v = reverse('app02:myindex', kwargs={'year':2019})这样即使app中URL的命名相同，我也可以反转得到正确的URL了。

# In settings/urls/main.py
from django.urls import include, pathurlpatterns = [path('<username>/blog/', include('foo.urls.blog')),
]# In foo/urls/blog.py
from django.urls import path
from . import viewsurlpatterns = [path('', views.blog.index),path('archive/', views.blog.archive),
]

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：from django.urls import path
from . import viewsurlpatterns = [path('<page_slug>-<page_id>/history/', views.history),path('<page_slug>-<page_id>/edit/', views.edit),path('<page_slug>-<page_id>/discuss/', views.discuss),path('<page_slug>-<page_id>/permissions/', views.permissions),
]
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：from django.urls import include, path
from . import viewsurlpatterns = [path('<page_slug>-<page_id>/', include([path('history/', views.history),path('edit/', views.edit),path('discuss/', views.discuss),path('permissions/', views.permissions),])),
]

from django.urls import path
from . import viewsurlpatterns = [path('articles/<int:year>/', views.year_archive, name='archive'),
]根据这种设计，对应于年度归档文件的URL是 /articles/<nnnn>/你可以使用以下方法在模板代码中获取这些：
<a href="{% url 'archive' 2012 %}">2012 Archive</a>或者在Python代码中：from django.http import HttpResponseRedirect
from django.urls import reversedef redirect_to_year(request):year = 2006return HttpResponseRedirect(reverse('archive', args=(year,)))

注意：如果直接使用name做反向解析(即使用了include)，也不需要设置app_name,但是使用namespace，需要设置app_name# 1.项目的urls
from django.urls import path, includeurlpatterns = [path('myapp/', include('MyApp.urls', namespace='my')),path('yourapp/', include('YourApp.urls', namespace='you')),
]# 2.1 MyApp.urls.py
from django.urls import path
from MyApp import viewsapp_name = 'myxxx'  # 在各个APP级别的urls中设置app_name

urlpatterns = [path('index/', views.index, name="index"),path('home/', views.home, name="home"),
]# 2.2 MyApp.Views.py
from django.shortcuts import render, redirect, HttpResponse
from django.urls import reversedef index(request):return HttpResponse("MyApp-index")def home(request):print("home")return redirect(reverse('my:index'))# return redirect(reverse('myxxx:index'))  # 也可以使用app_name# 3.1 YourApp.urls.py
from django.urls import path
from YourApp import viewsapp_name = 'yourxxx'  # 在各个APP级别的urls中设置app_name

urlpatterns = [path('index/', views.index, name="index"),path('hello/', views.hello, name="hello"),
]# 3.2 YourApp.Views.py
from django.shortcuts import render, redirect, HttpResponse
from django.urls import reversedef index(request):return HttpResponse("YourApp-index")def hello(request):print("hello")return redirect(reverse('you:index'))# return redirect(reverse('yourxxx:index'))  # 也可以使用app_name# 4. 在模板中使用
<a href="{% url 'my:index' %}">myapp-index</a>  # 可以写namespace
<a href="{% url 'yourxxx:index' %}">your-index</a>  # 可以写app_name

Django1.0：hbook = models.ForeignKey('BookInfo')
Django2.0：hbook = models.ForeignKey('BookInfo', on_delete=models.CASCADE)