python - 学习Django，却对变量一头雾水

Question

我正在学习 Django 教程，我正处于创建投票应用程序的第 3 步。有一个名为“question_id”的变量，我无法理解它的确切定义或来源。我将在下面发布文件。我唯一的猜测是，当在 Models.py 中定义类问题时，这个变量是由 Django 在内部以某种方式创建的，但我不确定。它没有在“问题”类中定义。

这是我的文件:

View .py

from django.shortcuts import render
from django.http import HttpResponse
from django.template import loader

from .models import Question


def index(request):
    latest_question_list = Question.objects.order_by('-pub_date')[:5]
    context = {'latest_question_list': latest_question_list}
    return render(request, 'polls/index.html', context)


#def index(request):
#    return HttpResponse("Hello, world. You're at the polls index.")

def detail(request, question_id):
    return HttpResponse("You're looking at question %s." % question_id)

def results(request, question_id):
    response = "Your looking at result of question %s."
    return HttpResponse(response % question_id)

def vote(reqeust, question_id):
    return HttpResponse("You're voting on question %s." % question_id)

网址.py

from django.conf.urls import url

from . import views

urlpatterns = [
    #ex: /polls/
    url(r'^$', views.index, name='index'),
    #ex: /polls/5
    url(r'^(?P<question_id>[0-9]+/$)', views.detail, name='detail'),
    #ex: /polls/5/result/
    url(r'^(?P<question_id>[0-9]+/results/$)', views.results, name='results'),
    #ex: /polls/5/vote
    url(r'^(?P<question_id>[0-9]+/vote/$)', views.vote, name='vote'),
]

模型.py

import datetime

from django.db import models
from django.utils import timezone


class Question(models.Model):
    question_text = models.CharField(max_length=200)
    pub_date = models.DateTimeField('date published')

    def __str__(self):
        return self.question_text

    def was_published_recently(self):
        return self.pub_date >= timezone.now() - datetime.timedelta(days=1)



class Choice(models.Model):
    question = models.ForeignKey(Question, on_delete=models.CASCADE)
    choice_text = models.CharField(max_length=200)
    votes = models.IntegerField(default=0)

    def __str__(self):
        return self.choice_text

谢谢你的帮助， 内敏

Answer 1

显示的三个 View 中的question_id 是由django 自动创建的。为此，它将 url 作为输入。在这里定义

url(r'^(?P<question_id>[0-9]+/$)', views.detail, name='detail'),

因此，如果您在浏览器中输入 polls/somenumber/，您的名为 detail 的 View 将传递一个名为 question_id 的变量和一个值一些

urls.py 中使用的正则表达式确保这是一个数字而不是其他东西。

有关更多信息，请参阅:https://docs.djangoproject.com/en/1.10/topics/http/urls/