Django/Python 初学者：执行 python manage.py syncdb 时出错 - 找不到 psycopg2

Question

我在Macports上安装了Python 2.6、psycopg2和pgAdmin3。我的settings.py文件内容是：

DATABASE_ENGINE = 'postgresql_psycopg2'           # 'postgresql_psycopg2', 'postgresql', 'mysql', 'sqlite3' or 'oracle'.
DATABASE_NAME = 'mysite'             # Or path to database file if using sqlite3.
DATABASE_USER = 'postgres'             # Not used with sqlite3.
DATABASE_PASSWORD = ''         # Not used with sqlite3.
DATABASE_HOST = ''             # Set to empty string for localhost. Not used with sqlite3.
DATABASE_PORT = ''             # Set to empty string for default. Not used with sqlite3.

当我运行命令python manage.py syncdb时，出现的错误是：

Traceback (most recent call last):
  File "manage.py", line 11, in <module>
    execute_manager(settings)
  File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/django/core/management/__init__.py", line 362, in execute_manager
    utility.execute()
  File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/django/core/management/__init__.py", line 303, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/django/core/management/base.py", line 195, in run_from_argv
    self.execute(*args, **options.__dict__)
  File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/django/core/management/base.py", line 221, in execute
    self.validate()
  File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/django/core/management/base.py", line 249, in validate
    num_errors = get_validation_errors(s, app)
  File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/django/core/management/validation.py", line 22, in get_validation_errors
    from django.db import models, connection
  File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/django/db/__init__.py", line 41, in <module>
    backend = load_backend(settings.DATABASE_ENGINE)
  File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/django/db/__init__.py", line 17, in load_backend
    return import_module('.base', 'django.db.backends.%s' % backend_name)
  File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/django/utils/importlib.py", line 35, in import_module
    __import__(name)
  File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/django/db/backends/postgresql_psycopg2/base.py", line 22, in <module>
    raise ImproperlyConfigured("Error loading psycopg2 module: %s" % e)
django.core.exceptions.ImproperlyConfigured: Error loading psycopg2 module: No module named psycopg2

请注意，我对这些东西完全是个新手。我原本是做PHP的，现在想尝试用Python做一个小个人项目。我需要“开启”Postgres吗？

另外，当我运行命令sudo python manage.py runserver 8080时，出现了这个错误：

Validating models...
Unhandled exception in thread started by <function inner_run at 0x1242670>
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/django/core/management/commands/runserver.py", line 48, in inner_run
    self.validate(display_num_errors=True)
  File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/django/core/management/base.py", line 249, in validate
    num_errors = get_validation_errors(s, app)
  File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/django/core/management/validation.py", line 22, in get_validation_errors
    from django.db import models, connection
  File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/django/db/__init__.py", line 41, in <module>
    backend = load_backend(settings.DATABASE_ENGINE)
  File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/django/db/__init__.py", line 17, in load_backend
    return import_module('.base', 'django.db.backends.%s' % backend_name)
  File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/django/utils/importlib.py", line 35, in import_module
    __import__(name)
  File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/django/db/backends/postgresql_psycopg2/base.py", line 22, in <module>
    raise ImproperlyConfigured("Error loading psycopg2 module: %s" % e)
django.core.exceptions.ImproperlyConfigured: Error loading psycopg2 module: No module named psycopg2

请给我一些指导。任何回复我都非常感激。

谢谢，

Wenbert!

Answer 1

为了说明，我遇到同样的错误，但原因不同：

我把

'ENGINE': 'django.db.backends.postgresql'

写成了

'ENGINE': 'django.db.backends.postgresql_psycopg2'

在 settings.py 文件里。

Answer 2

如果你已经安装了 pip，那么只需要运行下面的命令来安装缺少的扩展：

$ pip install psycopg2

Answer 3

你的 psycopg2 安装好像有问题——Python 找不到它。这是 Python 安装的问题，不是 Django 的问题。

你可以尝试用 Python 解释器手动加载它，看看能不能成功：

$ python
>>> import psycopg2

如果出现 ImportError 错误，那说明你的安装有问题。要查看 Python 查找模块的所有目录，可以使用 sys.path：

$ python
>>> import sys
>>> print sys.path

你还可以通过修改 sys.path 变量来添加自定义目录，让 Python 在这些目录中查找模块。记得在相关的 import 语句之前做这个：

import sys
sys.path.append("my-path")

# ...
import psycopg2