Django无法找到psycopg2模块

Question

我正在安装Python 3.5、Django 1.10和Psycopg2 2.7.1在Amazon EC2服务器上，以便使用Postgresql数据库。我正在虚拟环境中使用Python 3，并遵循经典的安装步骤：

cd /home/mycode
virtualenv-3.5 p3env
source p3env/bin/activate
pip install django
cd kenbot
django-admin startproject kenbot
pip install psycopg2

接下来我编辑了项目中的settings.py文件，定义了DATABASE设置：

DATABASES = {
'default': {
    'ENGINE': 'django.db.backends.postgresql_psycopg2',
    'NAME': 'deleted',
    'USER': 'deleted',
    'PASSWORD': 'deleted',
    'HOST': 'deleted',
    'PORT': '5432',
}   

最后，在虚拟环境中输入以下命令：

python manage.py makemigrations

并且出现以下错误：

Traceback (most recent call last):
  File "/home/mycode/p3env/local/lib/python3.5/dist-packages/django/db/backends/postgresql/base.py", line 20, in <module>
    import psycopg2 as Database
ImportError: No module named 'psycopg2'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "manage.py", line 22, in <module>
    execute_from_command_line(sys.argv)
  File "/home/mycode/p3env/local/lib/python3.5/dist-packages/django/core/management/__init__.py", line 367, in execute_from_command_line
    utility.execute()
  File "/home/mycode/p3env/local/lib/python3.5/dist-packages/django/core/management/__init__.py", line 341, in execute
    django.setup()
  File "/home/mycode/p3env/local/lib/python3.5/dist-packages/django/__init__.py", line 27, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/home/mycode/p3env/local/lib/python3.5/dist-packages/django/apps/registry.py", line 108, in populate
    app_config.import_models(all_models)
  File "/home/mycode/p3env/local/lib/python3.5/dist-packages/django/apps/config.py", line 199, in import_models
    self.models_module = import_module(models_module_name)
  File "/home/mycode/p3env/lib64/python3.5/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 986, in _gcd_import
  File "<frozen importlib._bootstrap>", line 969, in _find_and_load
  File "<frozen importlib._bootstrap>", line 958, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 673, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 662, in exec_module
  File "<frozen importlib._bootstrap>", line 222, in _call_with_frames_removed
  File "/home/mycode/p3env/local/lib/python3.5/dist-packages/django/contrib/auth/models.py", line 4, in <module>
    from django.contrib.auth.base_user import AbstractBaseUser, BaseUserManager
  File "/home/mycode/p3env/local/lib/python3.5/dist-packages/django/contrib/auth/base_user.py", line 52, in <module>
    class AbstractBaseUser(models.Model):
  File "/home/mycode/p3env/local/lib/python3.5/dist-packages/django/db/models/base.py", line 119, in __new__
    new_class.add_to_class('_meta', Options(meta, app_label))
  File "/home/mycode/p3env/local/lib/python3.5/dist-packages/django/db/models/base.py", line 316, in add_to_class
    value.contribute_to_class(cls, name)
  File "/home/mycode/p3env/local/lib/python3.5/dist-packages/django/db/models/options.py", line 214, in contribute_to_class
    self.db_table = truncate_name(self.db_table, connection.ops.max_name_length())
  File "/home/mycode/p3env/local/lib/python3.5/dist-packages/django/db/__init__.py", line 33, in __getattr__
    return getattr(connections[DEFAULT_DB_ALIAS], item)
  File "/home/mycode/p3env/local/lib/python3.5/dist-packages/django/db/utils.py", line 211, in __getitem__
    backend = load_backend(db['ENGINE'])
  File "/home/mycode/p3env/local/lib/python3.5/dist-packages/django/db/utils.py", line 115, in load_backend
    return import_module('%s.base' % backend_name)
  File "/home/mycode/p3env/lib64/python3.5/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "/home/mycode/p3env/local/lib/python3.5/dist-packages/django/db/backends/postgresql/base.py", line 24, in <module>
    raise ImproperlyConfigured("Error loading psycopg2 module: %s" % e)
django.core.exceptions.ImproperlyConfigured: Error loading psycopg2 module: No module named 'psycopg2'

我在stackoverflow上没有找到这个问题。可能有一个相关的问题，当我浏览我的虚拟环境目录时，我注意到django安装在/home/mycode/p3env/lib/python3.5/dist-packages，而psysopg2位于/home/mycode/p3env/lib64/python3.5/dist-packages。谢谢您的帮助！

- Ken

---

我已经解决了这个问题，只需要再次运行 pip install psycopg2 即可。 - Cody

你的 psycopg2 包应该与 Django 存在于同一个 Python 发行版中。由于两者都是 Python3.5，你可以直接复制它。也许你在虚拟环境未激活时安装了它？ - dentemm

@dentemm 当我安装它时，虚拟环境肯定是激活的。但是，简单地复制文件就解决了问题。谢谢！ - Ken

@Cody 谢谢...不起作用。 - Ken

我也遇到了这个问题。当PGSQL是支持的数据库之一时，这并不会给人留下很好的印象。 - Alan B

Answer 1

根据@dentemm的建议：将所有psysopg2目录从它们当前位于lib64目录的位置复制到django安装的目录/home/mycode/p3env/lib/python3.5/dist-packages中解决了该问题。

- Ken

Answer 2

卸载再重新安装库真的很有帮助！

(venv)$ pip uninstall psycopg2

---

(venv)$ pip安装psycopg2

- TINA CHANDWANI