Django Generic Views: In the tutorial, how does DetailView automatically provide the variable?

Question

It involves generic views, specifically the DetailView and it's explanation in the Django tutorial part 4.

My urls looks like this:

from django.conf.urls import patterns, url

from polls import views

urlpatterns = patterns('',
    url(r'^$', views.IndexView.as_view(), name='index'),
    url(r'^(?P<pk>\d+)/$', views.DetailView.as_view(), name='detail'),
    url(r'^(?P<pk>\d+)/results/$', views.ResultsView.as_view(), name='results'),
    url(r'^(?P<question_id>\d+)/vote/$', views.vote, name='vote'),)

My views looks like this:

from django.shortcuts import get_object_or_404, render
from django.http import HttpResponseRedirect
from django.core.urlresolvers import reverse
from django.views import generic

from polls.models import Choice, Question


class IndexView(generic.ListView):
    template_name = 'polls/index.html'
    context_object_name = 'latest_question_list'

def get_queryset(self):
    """Return the last five published questions."""
    return Question.objects.order_by('-pub_date')[:5]


class DetailView(generic.DetailView):
    model = Question
    template_name = 'polls/detail.html'


class ResultsView(generic.DetailView):
    model = Question
    template_name = 'polls/results.html'


def vote(request, question_id):
    ... # same as above

This is all from the tutorial btw. Let's look at my detail.html template:

<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>

How does my detail template know that the question variable (as in, question.question_text) refers to my Question model? I've never declared it, and the model name begins with a capital letter.

The tutorial says, "For DetailView the question variable is provided automatically – since we’re using a Django model (Question), Django is able to determine an appropriate name for the context variable."

How does it do that? If I go in and capitalize the variable, it doesn't work anymore. Where is DetailView getting this variable from?

Answer 1

This data is available in the model's meta information. You can get it in your code too:

>>> Question._meta.model_name
'question'