Django 无法加载 psycopg2 模块。 Python 也无法加载它，即使我在运行 pip list 时看到它

Question

我将我的个人项目从我的 git 存储库克隆到我的新笔记本电脑（mac、big sur、M1 芯片）上，但我在使用 psycopg2 时遇到了一些问题。在相当头痛之后，我能够安装 psycopg2。应该安装我所有的依赖项。

现在，当我输入 python3 manage.py runserver 时，出现以下错误：

Exception in thread django-main-thread:
Traceback (most recent call last):
  File "/Users/jeff/Desktop/Project-BookBuddy/BookBuddy/env/lib/python3.9/site-packages/django/db/backends/postgresql/base.py", line 25, in <module>
    import psycopg2 as Database
  File "/Users/jeff/Desktop/Project-BookBuddy/BookBuddy/env/lib/python3.9/site-packages/psycopg2/__init__.py", line 51, in <module>
    from psycopg2._psycopg import (                     # noqa
ImportError: dlopen(/Users/jeff/Desktop/Project-BookBuddy/BookBuddy/env/lib/python3.9/site-packages/psycopg2/_psycopg.cpython-39-darwin.so, 2): Symbol not found: _PQbackendPID
  Referenced from: /Users/jeff/Desktop/Project-BookBuddy/BookBuddy/env/lib/python3.9/site-packages/psycopg2/_psycopg.cpython-39-darwin.so
  Expected in: flat namespace
 in /Users/jeff/Desktop/Project-BookBuddy/BookBuddy/env/lib/python3.9/site-packages/psycopg2/_psycopg.cpython-39-darwin.so

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/threading.py", line 954, in _bootstrap_inner
    self.run()
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/threading.py", line 892, in run
    self._target(*self._args, **self._kwargs)
  File "/Users/jeff/Desktop/Project-BookBuddy/BookBuddy/env/lib/python3.9/site-packages/django/utils/autoreload.py", line 53, in wrapper
    fn(*args, **kwargs)
  File "/Users/jeff/Desktop/Project-BookBuddy/BookBuddy/env/lib/python3.9/site-packages/django/core/management/commands/runserver.py", line 110, in inner_run
    autoreload.raise_last_exception()
  File "/Users/jeff/Desktop/Project-BookBuddy/BookBuddy/env/lib/python3.9/site-packages/django/utils/autoreload.py", line 76, in raise_last_exception
    raise _exception[1]
  File "/Users/jeff/Desktop/Project-BookBuddy/BookBuddy/env/lib/python3.9/site-packages/django/core/management/__init__.py", line 357, in execute
    autoreload.check_errors(django.setup)()
  File "/Users/jeff/Desktop/Project-BookBuddy/BookBuddy/env/lib/python3.9/site-packages/django/utils/autoreload.py", line 53, in wrapper
    fn(*args, **kwargs)
  File "/Users/jeff/Desktop/Project-BookBuddy/BookBuddy/env/lib/python3.9/site-packages/django/__init__.py", line 24, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/Users/jeff/Desktop/Project-BookBuddy/BookBuddy/env/lib/python3.9/site-packages/django/apps/registry.py", line 114, in populate
    app_config.import_models()
  File "/Users/jeff/Desktop/Project-BookBuddy/BookBuddy/env/lib/python3.9/site-packages/django/apps/config.py", line 211, in import_models
    self.models_module = import_module(models_module_name)
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1030, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1007, in _find_and_load
  File "<frozen importlib._bootstrap>", line 986, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 680, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 790, in exec_module
  File "<frozen importlib._bootstrap>", line 228, in _call_with_frames_removed
  File "/Users/jeff/Desktop/Project-BookBuddy/BookBuddy/users/models.py", line 2, in <module>
    from django.contrib.auth.models import User
  File "/Users/jeff/Desktop/Project-BookBuddy/BookBuddy/env/lib/python3.9/site-packages/django/contrib/auth/models.py", line 2, in <module>
    from django.contrib.auth.base_user import AbstractBaseUser, BaseUserManager
  File "/Users/jeff/Desktop/Project-BookBuddy/BookBuddy/env/lib/python3.9/site-packages/django/contrib/auth/base_user.py", line 48, in <module>
    class AbstractBaseUser(models.Model):
  File "/Users/jeff/Desktop/Project-BookBuddy/BookBuddy/env/lib/python3.9/site-packages/django/db/models/base.py", line 122, in __new__
    new_class.add_to_class('_meta', Options(meta, app_label))
  File "/Users/jeff/Desktop/Project-BookBuddy/BookBuddy/env/lib/python3.9/site-packages/django/db/models/base.py", line 326, in add_to_class
    value.contribute_to_class(cls, name)
  File "/Users/jeff/Desktop/Project-BookBuddy/BookBuddy/env/lib/python3.9/site-packages/django/db/models/options.py", line 206, in contribute_to_class
    self.db_table = truncate_name(self.db_table, connection.ops.max_name_length())
  File "/Users/jeff/Desktop/Project-BookBuddy/BookBuddy/env/lib/python3.9/site-packages/django/db/__init__.py", line 28, in __getattr__
    return getattr(connections[DEFAULT_DB_ALIAS], item)
  File "/Users/jeff/Desktop/Project-BookBuddy/BookBuddy/env/lib/python3.9/site-packages/django/db/utils.py", line 214, in __getitem__
    backend = load_backend(db['ENGINE'])
  File "/Users/jeff/Desktop/Project-BookBuddy/BookBuddy/env/lib/python3.9/site-packages/django/db/utils.py", line 111, in load_backend
    return import_module('%s.base' % backend_name)
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "/Users/jeff/Desktop/Project-BookBuddy/BookBuddy/env/lib/python3.9/site-packages/django/db/backends/postgresql/base.py", line 29, in <module>
    raise ImproperlyConfigured("Error loading psycopg2 module: %s" % e)
django.core.exceptions.ImproperlyConfigured: Error loading psycopg2 module: dlopen(/Users/jeff/Desktop/Project-BookBuddy/BookBuddy/env/lib/python3.9/site-packages/psycopg2/_psycopg.cpython-39-darwin.so, 2): Symbol not found: _PQbackendPID
  Referenced from: /Users/jeff/Desktop/Project-BookBuddy/BookBuddy/env/lib/python3.9/site-packages/psycopg2/_psycopg.cpython-39-darwin.so
  Expected in: flat namespace
 in /Users/jeff/Desktop/Project-BookBuddy/BookBuddy/env/lib/python3.9/site-packages/psycopg2/_psycopg.cpython-39-darwin.so

django 似乎无法加载 psycopg2。我基于：

"raise ImproperlyConfigured("加载 psycopg2 模块时出错：%s" % e)"

我知道它安装在我的虚拟环境中，当我运行 pip list 时可以看到它。

当我运行 python3 shell 并尝试导入 psycopg2 时，出现以下错误：

Python 3.9.4 (v3.9.4:1f2e3088f3, Apr  4 2021, 12:32:44) 
[Clang 6.0 (clang-600.0.57)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import psycopg2
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/jeff/Desktop/Project-BookBuddy/BookBuddy/env/lib/python3.9/site-packages/psycopg2/__init__.py", line 51, in <module>
    from psycopg2._psycopg import (                     # noqa
ImportError: dlopen(/Users/jeff/Desktop/Project-BookBuddy/BookBuddy/env/lib/python3.9/site-packages/psycopg2/_psycopg.cpython-39-darwin.so, 2): Symbol not found: _PQbackendPID
  Referenced from: /Users/jeff/Desktop/Project-BookBuddy/BookBuddy/env/lib/python3.9/site-packages/psycopg2/_psycopg.cpython-39-darwin.so
  Expected in: flat namespace
 in /Users/jeff/Desktop/Project-BookBuddy/BookBuddy/env/lib/python3.9/site-packages/psycopg2/_psycopg.cpython-39-darwin.so

我认为这个问题可能与 python3 在哪里寻找 psycopg2 模块有关，但我对 django 很陌生（对 macOS 也是全新的），所以我不完全确定。你认为是这样吗？如果是这样，我如何查看 python 在哪里寻找模块，以及如何查看模块的实际位置（我猜应该在我的虚拟环境中）？

Answer 1

假设您的机器上安装了 PostgreSQL，pip install psycopg2-binary 很可能会解决您的问题。