python - 为什么当我交换 url 模式成员的顺序时，错误会有所不同

Question

Note: I'm not requesting for a help to fix the errors, but to ask the reason why they differ by interchanging the order of url patterns.

以下是我的 urls.py我的 Django 应用程序 ( basic_app ) 看起来像:

from django.urls import path, re_path
from basic_app import views

app_name = 'basic_app'

urlpatterns = [
    path('', views.SchoolListView.as_view(), name='list'),
    re_path(r'^(?P<pk>[-\w]+)/$', views.SchoolDetailView.as_view(), name='detail'),
    path('create/', views.SchoolCreateView.as_view(), name='create'),
]

当我运行服务器并输入网址时 http://127.0.0.1:8000/basic_app/create/ ，它抛出以下错误:

ValueError at /basic_app/create/
Field 'id' expected a number but got 'create'.
Request Method: GET
Request URL:    http://127.0.0.1:8000/basic_app/create/
Django Version: 3.2.4
Exception Type: ValueError
Exception Value:    
Field 'id' expected a number but got 'create'.

有趣的是，当我将第二个和第三个 url 模式的顺序交换如下时:

from django.urls import path, re_path
from basic_app import views

app_name = 'basic_app'

urlpatterns = [
    path('', views.SchoolListView.as_view(), name='list'),
    path('create/', views.SchoolCreateView.as_view(), name='create'),
    re_path(r'^(?P<pk>[-\w]+)/$', views.SchoolDetailView.as_view(), name='detail'),
]

我得到了一个不同的错误:

ImproperlyConfigured at /basic_app/create/
Using ModelFormMixin (base class of SchoolCreateView) without the 'fields' attribute is prohibited.
Request Method: GET
Request URL:    http://127.0.0.1:8000/basic_app/create/
Django Version: 3.2.4
Exception Type: ImproperlyConfigured
Exception Value:    
Using ModelFormMixin (base class of SchoolCreateView) without the 'fields' attribute is prohibited.

我是 Django 的新手，对这个事件很好奇。为什么python不让 create/转到下一个模式进行检查，因为它不适合第一个模式？

我的 views.py文件如下所示:

from django.shortcuts import render
from django.views.generic import (
    View,
    TemplateView,
    ListView,
    DetailView,
    CreateView,
    UpdateView,
    DeleteView
)
from . import models


# Create your views here.
class IndexView(TemplateView):
    template_name = 'index.html'


class SchoolListView(ListView):
    context_object_name = 'schools'
    model = models.School


class SchoolDetailView(DetailView):
    context_object_name = 'school_detail'
    model = models.School
    template_name = 'basic_app/school_detail.html'


class SchoolCreateView(CreateView):
    model = models.School

Answer 1

Django 旨在匹配 url 的顶部到底部。如果您因此访问 /basic_app/create/ ，以及带有 SchoolDetailView 的规则首先，它将触发该 View ，因为 create/与正则表达式匹配 (?P<pk>[-\w+])/$ .由于您的对象的主键可能是 AutoField , 匹配 create/ 没有意义与 pk ，因为我们希望这是一个整数。
另一个问题是您的 SchoolCreateView未正确配置，您需要指定在 CreateView 中将使用哪些字段，所以我们可以通过以下方式实现:

class SchoolCreateView(CreateView):
    model = models.School
    fields = '__all__'

我们可以细化 re_path仅使用 int 而非任意 slug 触发的详细 View :

re_path(r'^(?P<pk>\d+)/$', views.SchoolDetailView.as_view(), name='detail'),

或使用路径转换器:

path(r'<int:pk>/', views.SchoolDetailView.as_view(), name='detail'),