问题
I've been impressed how rapidly a functional website can go together with generic views in the tutorials. Also, the workflow for form processing is nice. I used the ModelForm helper class to create a form from a model I made and was delighted to see that so much functionality came together. When I used the generic list_detail.object_detail I was disappointed that all that I could display were fields individually. I knew the ModelForm class contained information for rendering, so I wanted to use the ModelForm with a generic view.
I was asking around on stackoverflow to get some direction, and appreciate the answers and comments from several posters. I've figured out how to get this to work, but there is a bug in DetailView. The solution includes a workaround.
To use a ModelView with the generic view and get all the fields to render automatically the following works:
Create a project, and in it create application inpatients.
If you have
# inpatients/models.py
class Inpatient(models.Model):
last_name = models.CharField(max_length=30)
first_name = models.CharField(max_length=30,blank=True)
address = models.CharField(max_length=50,blank=True)
city = models.CharField(max_length=60,blank=True)
state = models.CharField(max_length=30,blank=True)
DOB = models.DateField(blank=True,null=True)
notes = models.TextField(blank=True)
def __unicode__(self):
return u'%s, %s %s' % (self.last_name, self.first_name, self.DOB)
class InpatientForm(ModelForm):
class Meta:
model = Inpatient
and
# inpatients/views.py
from django.http import HttpResponse, HttpResponseRedirect
from django.shortcuts import render_to_response
from django.views.generic import DetailView
from portal.inpatients.models import *
def formtest(request):
if request.method == 'POST':
form = InpatientForm(request.POST)
if form.is_valid():
form.save()
return HttpResponseRedirect('/inpatients')
else:
form = InpatientForm()
return render_to_response("formtest.html", {'form': form})
class FormDetailView(DetailView):
model=Inpatient
context_object_name='inpatient' # defines the name in the template
template_name_field='inpatient_list_page.html'
def get_object(self):
inpatient=super(FormDetailView,self).get_object()
form=InpatientForm(instance=inpatient)
return form
def get_template_names(self):
return ['inpatient_list_page.html',]
and
#urls.py
from django.conf.urls.defaults import patterns, include, url
from django.views.generic import ListView
from portal.inpatients.models import Inpatient, InpatientForm
from portal.inpatients.views import FormDetailView
urlpatterns = patterns('',
(r'^formtest/$','portal.inpatients.views.formtest'),
(r'^inpatients/$', ListView.as_view(
model=Inpatient, template_name='inpatient_list_page.html')),
(r'^inpatient-detail/(?P<pk>\d+)/$', FormDetailView.as_view()),
)
# with a template containing
{% block content %}
<h2>Inpatients</h2>
<ul>
{% for aninpatient in object_list %}
<li><a href='/inpatient-detail/{{ aninpatient.id }}/'>
{{ aninpatient }}, id={{ aninpatient.id }}</a></li>
{% endfor %}
</ul>
{{ inpatient.as_p }}
{% endblock %}
# Yeah, kind of hokey. The template is for both the list view and detail view.
# Note how the form is rendered with one line - {{ inpatient.as_p }}
it works. The instructions for using class based generic views lives at https://docs.djangoproject.com/en/1.3/topics/class-based-views/ Instructions there are pretty clear. The key to making things work is to redefine get_object. In the documentation under the section "Performing extra work" it nicely describes how to do this, the steps being to call the original version of get_object, and then to the extra work. The bit that I realized is that the return object can be a ModelForm object. The object that get_object returns goes straight into the template in a render. By taking the retrieved inpatient object and running it through InpatientForm it can be passed to a view as a form which then renders itself.
As to the bug: The bug in DetailView is that the get_template_names function tries to make a template name from a structure that does not exist. In https://code.djangoproject.com/browser/django/trunk/django/views/generic/detail.py on lines 127 to 140 we have within SingleObjectTemplateResponseMixin.get_template_names:
127 # The least-specific option is the default <app>/<model>_detail.html;
128 # only use this if the object in question is a model.
129 if hasattr(self.object, '_meta'):
130 names.append("%s/%s%s.html" % (
131 self.object._meta.app_label,
132 self.object._meta.object_name.lower(),
133 self.template_name_suffix
134 ))
135 elif hasattr(self, 'model') and hasattr(self.model, '_meta'):
136 names.append("%s/%s%s.html" % (
137 self.model._meta.app_label,
138 self.model._meta.object_name.lower(),
139 self.template_name_suffix
140 ))
The error is that the code on line 131 is executed and dies with error message <'ModelFormOptions' object has no attribute 'app_label'>. I conclude that the _meta object is defined. I suppose that the problem is that in a ModelForm the class Meta is defined. That Meta probably doesn't have the fields set that are expected. The workaround is just to rewrite get_template_names and return the correct template.
I'm new to Django and Python. I appreciate the answers and comments by the contributors at the following previous questions I asked. ( Putting links in list_detail.object_list to list_detail.object_detail, Using form in object_detail, Rolling your own generic views in Django)
What should I do to report the bug?
回答1:
You are right I believe. This is a bug which stems from the fact that both ModelForm and Models have a _meta attribute. This same bug would exhibit itself anytime an object is returned from get_object() that contains a _meta attribute.
get_object does not have to return a Model instance. You can confirm this by looking at the source for DetailView and reading it's docstring:
class DetailView(SingleObjectTemplateResponseMixin, BaseDetailView):
"""
Render a "detail" view of an object.
By default this is a model instance looked up from `self.queryset`, but the
view will support display of *any* object by overriding `self.get_object()`.
"""
Notice that the doc string explicitly says that any object is supported by overriding self.get_object().
Another piece of corroborating evidence is from the location where this bug itself occurs which is the get_template_names method of SingleObjectTemplateResponseMixin.
# The least-specific option is the default <app>/<model>_detail.html;
# only use this if the object in question is a model.
if hasattr(self.object, '_meta'):
names.append("%s/%s%s.html" % (
self.object._meta.app_label,
self.object._meta.object_name.lower(),
self.template_name_suffix
))
elif hasattr(self, 'model') and hasattr(self.model, '_meta'):
names.append("%s/%s%s.html" % (
self.model._meta.app_label,
self.model._meta.object_name.lower(),
self.template_name_suffix
))
Again looking at this code, the comment itself say "If the object in question is a model". From this comment we can infer that the object doesn't always have to be a model.
However if you are trying to create a view that allows someone to edit/create/delete a model you really should have a look at the Editing Views which include FormView, CreateView, EditView and DeleteView. You can see more information for these at https://docs.djangoproject.com/en/1.3/ref/class-based-views/#editing-views.
To answer the question as to how to report the bug, you should follow the guidelines detailed at https://docs.djangoproject.com/en/1.3/internals/contributing/#reporting-bugs.
来源：https://stackoverflow.com/questions/6564068/using-class-based-generic-view-detailview-with-a-modelform-reveals-a-bug-how-t