Django App(四) Submit a form

经过前面的努力,到这里我们已经基本完成了,从服务器到浏览器的数据下发,还没有解决从浏览器到服务器的数据上传,这一节将创建一个Form获取从浏览器提交的数据

1.新建Form

接着前面建的项目,网上调查,每一个Question有多个Choice,当用户针对特定问题,可以提交选择,数据库记录每个Choice的vote数,所以新建:

polls/templates/detail.html

编写代码如下:

<h1>{{ question.question_text }}</h1>

{% if error_message %}<p><strong>{{ error_message }}</strong></p>{% endif %}


<form action="{% url 'polls:vote' question.id %}" method="post">
{% csrf_token %}
{% for choice in question.choice_set.all %}
    <input type="radio" name="choice" id="choice{{ forloop.counter }}" value="{{ choice.id }}" />
    <label for="choice{{ forloop.counter }}">{{ choice.choice_text }}</label><br />
{% endfor %}
<input type="submit" value="Vote" />
</form>

{% url ‘polls:vote’ question.id %}的写法,是为了防止页面硬编码[查看上一篇内容],引入的url的另一种写法, polls:vote 的写法是给polls/urls.py 加了url命名空间:

 1 from django.urls import path
 2 from . import views
 3 app_name="polls"
 4 urlpatterns=[
 5     path('',views.index,name='index'),
 6     path('<int:question_id>/detail',views.detail,name="detail"), #定义detail view
 7     path('<int:question_id>/results',views.results,name='results'),#定义格式:/参数[参数类型为int]/results
 8     #这里将原来的vote/<int:question_id>改成<Vote/<int:question_id>
 9     path('vote/<int:question_id>',views.vote,name='vote')  #定义格式:vote/参数[参数类型为int]
10 ]

上面建的表单要提交一个question_id 和 Choice_Id 到 /vote view,为了表单提交数据的安全性,这里指定使用POST传输,这点view没有特别要求,改造view/vote 对指定的question_id的choice_id的votes+1

2.接收Form数据并处理业务

修改polls/views.py/vote如下,(为了方便对比这里贴出来整个Views.py):

 1 from django.shortcuts import get_object_or_404, render
 2 from django.http import HttpResponseRedirect, HttpResponse
 3 from django.urls import reverse
 4 
 5 from .models import Choice, Question
 6 # ...
 7 def vote(request, question_id):
 8     question = get_object_or_404(Question, pk=question_id)
 9     try:
10         selected_choice = question.choice_set.get(pk=request.POST['choice'])
11     except (KeyError, Choice.DoesNotExist):
12         # Redisplay the question voting form.
13         return render(request, 'polls/detail.html', {
14             'question': question,
15             'error_message': "You didn't select a choice.",
16         })
17     else:
18         selected_choice.votes += 1
19         selected_choice.save()
20         # Always return an HttpResponseRedirect after successfully dealing
21         # with POST data. This prevents data from being posted twice if a
22         # user hits the Back button.
23         return HttpResponseRedirect(reverse('polls:results', args=(question.id,)))
24 
25 def index(request):
26     latest_question_list = Question.objects.order_by('-pub_date')[:5]
27 
28     context = {
29         'latest_question_list': latest_question_list,
30     }
31     return  render(request,'polls/index.html',context)
32 # ...
33 def detail(request, question_id):
34     question = get_object_or_404(Question, pk=question_id)
35     return render(request, 'polls/detail.html', {'question': question})
36 
37 def results(request, question_id):
38     response = "You're looking at the results of question %s."
39     return HttpResponse(response % question_id)

编辑polls/templates/polls/index.html如下:

{% if latest_question_list %}
    <ul>
    {% for question in latest_question_list %}
        <li><a href="{% url 'polls:detail' question.id %}">{{ question.question_text }}</a></li>
    {% endfor %}
    </ul>
{% else %}
    <p>No polls are available.</p>
{% endif %}