Django：Filter（）不返回任何内容

Question

When I try to use get() it gives me a multiple objects returned error. I tried filter and it returns absolutely nothing. Here is my code:

latest_poll_list = Score.objects.filter(user=user.id)

It doesn't return anything. Hopefully this is just a syntax error; not an error that I have to re-write the program. Thanks in advance.

get:

Environment:


Request Method: GET
Request URL: http://localhost:8000/scores/

Django Version: 1.3
Python Version: 2.5.5
Installed Applications:
['django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.sites',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'django.contrib.admin',
 'django.contrib.admindocs',
 'es']
Installed Middleware:
('django.middleware.common.CommonMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware')


Traceback:
File "/usr/local/lib/python2.5/site-packages/django/core/handlers/base.py" in get_response
  111.                         response = callback(request, *callback_args, **callback_kwargs)
File "/Users/julian/Documents/EpicScore/es/views.py" in scoreindex
  30.     latest_poll_list = Score.objects.get(user=request.user)
File "/usr/local/lib/python2.5/site-packages/django/db/models/manager.py" in get
  132.         return self.get_query_set().get(*args, **kwargs)
File "/usr/local/lib/python2.5/site-packages/django/db/models/query.py" in get
  351.                 % (self.model._meta.object_name, num, kwargs))

Exception Type: MultipleObjectsReturned at /scores/
Exception Value: get() returned more than one Score -- it returned 3! Lookup parameters were     {'user': <User: jmeyer>}

Answer 1

Your get call in the traceback is not equivalent to the filter call in your question:

latest_poll_list = Score.objects.get(user=request.user)
    !=
latest_poll_list = Score.objects.filter(user=user.id)

In the first you are passing an object, user as the argument, in the second you're passing the id value (probably an integer). Also, without seeing the rest of your code we don't know if user and request.user are the same.

If you simply exchange get for filter you should end up with the expected result:

latest_poll_list = Score.objects.filter(user=request.user)

Otherwise you could do:

latest_poll_list = Score.objects.filter(user__id=request.user.id)

If you pass in the user object, the query is internally comparing user.id against the database column user_id which is how the data for the ForeignKey is actually stored.

Answer 2

You have a corrupted dataset, or maybe your models aren't working like you think they are. Somehow you managed to make it so that the user isn't a unique identifier for the Score.

As for why filter isn't returning anything, maybe it's because you're calling it differently?

filter(user=user.id)

vs.

get(user=request.user)

This leads me to believe the user is a remote key that gets automagically handled by django, rather than a raw number. Your use of filter is using a raw number, your use of get is using the more idiomatic object-as-relation way.

Answer 3

如果Score表的user字段是User表的ForeignKey，并且您有一个本地变量user也是User对象，那么您应该

latest_poll_list = Score.objects.filter(user=user)