AttributeError at /index/

'module' object has no attribute 'pk'

Request Method: POST
Request URL: http://127.0.0.1:8000/index/
Django Version: 1.7.4
Exception Type: AttributeError
Exception Value:

'module' object has no attribute 'pk'

Exception Location: D:\programs\python27\lib\site-packages\django-1.7.4-py2.7.egg\django\contrib\auth__init__.py in login, line 88
Python Executable: D:\programs\python27\python.exe
Python Version: 2.7.7
Python Path:

['D:\programs\Django-1.7.4\Django-1.7.4\django\bin\mysite',
'D:\programs\python27\lib\site-packages\django-1.7.4-py2.7.egg',
'D:\programs\Django-1.7.4\Django-1.7.4\django\bin\mysite',
'C:\Windows\system32\python27.zip',
'D:\programs\python27\DLLs',
'D:\programs\python27\lib',
'D:\programs\python27\lib\plat-win',
'D:\programs\python27\lib\lib-tk',
'D:\programs\python27',
'D:\programs\python27\lib\site-packages',
'D:\programs\python27\lib\site-packages\PIL']

Server time: Tue, 21 Apr 2015 10:45:12 +0800

以上是尝试调用login(request, user)时的报错信息