我想在我的Django models.py文件中进行以下导入：
from django.contrib.postgres.fields import ArrayField
我阅读了这份文档https://docs.djangoproject.com/en/dev/ref/contrib/，并在我的settings.py中的INSTALLED_APPS中添加了'django.contrib.postgres'，但是当我尝试同步我的数据库或运行服务器时，我收到了“ImportError：没有名为postgres的模块”的错误信息。
我还需要做些什么或安装其他东西吗？django.contrib.postgres是核心分发的一部分，对吧？
这是追溯信息：
Traceback (most recent call last):
File "manage.py", line 10, in <module>
execute_from_command_line(sys.argv)
File "c:\Python27\lib\site-packages\django\core\management\__init__.py", line 399, in execute_from_com
utility.execute()
File "c:\Python27\lib\site-packages\django\core\management\__init__.py", line 392, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "c:\Python27\lib\site-packages\django\core\management\base.py", line 242, in run_from_argv
self.execute(*args, **options.__dict__)
File "c:\Python27\lib\site-packages\django\core\management\base.py", line 280, in execute
translation.activate('en-us')
File "c:\Python27\lib\site-packages\django\utils\translation\__init__.py", line 130, in activate
return _trans.activate(language)
File "c:\Python27\lib\site-packages\django\utils\translation\trans_real.py", line 188, in activate
_active.value = translation(language)
File "c:\Python27\lib\site-packages\django\utils\translation\trans_real.py", line 177, in translation
default_translation = _fetch(settings.LANGUAGE_CODE)
File "c:\Python27\lib\site-packages\django\utils\translation\trans_real.py", line 159, in _fetch
app = import_module(appname)
File "c:\Python27\lib\site-packages\django\utils\importlib.py", line 40, in import_module
__import__(name)
ImportError: No module named postgres