在使用ipython测试django项目时，出现了下面的错误：

In [5]: from polls.models import Polls,Choice
---------------------------------------------------------------------------
ImproperlyConfigured                      Traceback (most recent call last)
<ipython-input-5-b855efac1c5f> in <module>()
----> 1 from polls.models import Polls,Choice

/home/mark/Workspace/Python/PythonWeb/news/polls/models.py in <module>()
      1 from django.db import models
----> 2 class Polls(models.Model):
      3     question = models.CharField(max_length = 200)
      4     publish_date = models.DateTimeField('pulish_datetime')
      5 

/home/mark/Workspace/Python/PythonWeb/news/polls/models.py in Polls()
      1 from django.db import models
      2 class Polls(models.Model):
----> 3     question = models.CharField(max_length = 200)
      4     publish_date = models.DateTimeField('pulish_datetime')
      5 

/usr/local/lib/python2.7/dist-packages/django/db/models/fields/__init__.pyc in __init__(self, *args, **kwargs)
   1079 
   1080     def __init__(self, *args, **kwargs):
-> 1081         super(CharField, self).__init__(*args, **kwargs)
   1082         self.validators.append(validators.MaxLengthValidator(self.max_length))
   1083 

/usr/local/lib/python2.7/dist-packages/django/db/models/fields/__init__.pyc in __init__(self, verbose_name, name, primary_key, max_length, unique, blank, null, db_index, rel, default, editable, serialize, unique_for_date, unique_for_month, unique_for_year, choices, help_text, db_column, db_tablespace, auto_created, validators, error_messages)
    159         self.help_text = help_text
    160         self.db_column = db_column
--> 161         self.db_tablespace = db_tablespace or settings.DEFAULT_INDEX_TABLESPACE
    162         self.auto_created = auto_created
    163 

/usr/local/lib/python2.7/dist-packages/django/conf/__init__.pyc in __getattr__(self, name)
     46     def __getattr__(self, name):
     47         if self._wrapped is empty:
---> 48             self._setup(name)
     49         return getattr(self._wrapped, name)
     50 

/usr/local/lib/python2.7/dist-packages/django/conf/__init__.pyc in _setup(self, name)
     40                 "You must either define the environment variable %s "
     41                 "or call settings.configure() before accessing settings."
---> 42                 % (desc, ENVIRONMENT_VARIABLE))
     43 
     44         self._wrapped = Settings(settings_module)

ImproperlyConfigured: Requested setting DEFAULT_INDEX_TABLESPACE, but settings are not configured. You must either define the environment variable DJANGO_SETTINGS_MODULE or call settings.configure() before accessing settings.

解决办法：

在import之前加入一下代码导入settings：
 from django.conf import settings  
 settings.configure()