我在我的项目中同时使用 python-social-auth 和电子邮件注册。对于用户模型，我使用 AbstractBaseUser 的子类：
class User(AbstractBaseUser):
USERNAME_FIELD = 'email'
AUTH_USER_MODEL = 'userprofile.User'
但是，当使用他的电子邮件 (demo@demo.com) 和密码注册的用户尝试使用与同一电子邮件地址关联的 Facebook 帐户登录时，我收到以下错误：
IntegrityError at /social/complete/facebook/
duplicate key value violates unique constraint "userprofile_user_email_key"
DETAIL: Key (email)=(demo@demo.com) already exists.
/Users/vera/.virtualenvs/app/lib/python2.7/site-packages/django/core/handlers/base.py in get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs) ...
/Users/vera/.virtualenvs/app/lib/python2.7/site-packages/django/views/decorators/csrf.py in wrapped_view
return view_func(*args, **kwargs) ...
/Users/vera/.virtualenvs/app/lib/python2.7/site-packages/social/apps/django_app/utils.py in wrapper
return func(request, backend, *args, **kwargs) ...
/Users/vera/.virtualenvs/app/lib/python2.7/site-packages/social/apps/django_app/views.py in complete
redirect_name=REDIRECT_FIELD_NAME, *args, **kwargs) ...
/Users/vera/.virtualenvs/app/lib/python2.7/site-packages/social/actions.py in do_complete
*args, **kwargs) ...
/Users/vera/.virtualenvs/app/lib/python2.7/site-packages/social/strategies/base.py in complete
return self.backend.auth_complete(*args, **kwargs) ...
/Users/vera/.virtualenvs/app/lib/python2.7/site-packages/social/backends/facebook.py in auth_complete
return self.do_auth(access_token, response, *args, **kwargs) ...
/Users/vera/.virtualenvs/app/lib/python2.7/site-packages/social/backends/facebook.py in do_auth
return self.strategy.authenticate(*args, **kwargs) ...
/Users/vera/.virtualenvs/app/lib/python2.7/site-packages/social/strategies/django_strategy.py in authenticate
return authenticate(*args, **kwargs) ...
/Users/vera/.virtualenvs/app/lib/python2.7/site-packages/django/contrib/auth/__init__.py in authenticate
user = backend.authenticate(**credentials) ...
/Users/vera/.virtualenvs/app/lib/python2.7/site-packages/social/backends/base.py in authenticate
return self.pipeline(pipeline, *args, **kwargs) ...
/Users/vera/.virtualenvs/app/lib/python2.7/site-packages/social/backends/base.py in pipeline
out = self.run_pipeline(pipeline, pipeline_index, *args, **kwargs) ...
/Users/vera/.virtualenvs/app/lib/python2.7/site-packages/social/backends/base.py in run_pipeline
result = func(*args, **out) or {} ...
/Users/vera/.virtualenvs/app/lib/python2.7/site-packages/social/pipeline/user.py in user_details
strategy.storage.user.changed(user) ...
/Users/vera/.virtualenvs/app/lib/python2.7/site-packages/social/storage/django_orm.py in changed
user.save() ...
/Users/vera/.virtualenvs/app/lib/python2.7/site-packages/django/db/models/base.py in save
force_update=force_update, update_fields=update_fields) ...
/Users/vera/.virtualenvs/app/lib/python2.7/site-packages/django/db/models/base.py in save_base
updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields) ...
/Users/vera/.virtualenvs/app/lib/python2.7/site-packages/django/db/models/base.py in _save_table
forced_update) ...
/Users/vera/.virtualenvs/app/lib/python2.7/site-packages/django/db/models/base.py in _do_update
return filtered._update(values) > 0 ...
/Users/vera/.virtualenvs/app/lib/python2.7/site-packages/django/db/models/query.py in _update
return query.get_compiler(self.db).execute_sql(None) ...
/Users/vera/.virtualenvs/app/lib/python2.7/site-packages/django/db/models/sql/compiler.py in execute_sql
cursor = super(SQLUpdateCompiler, self).execute_sql(result_type) ...
/Users/vera/.virtualenvs/app/lib/python2.7/site-packages/django/db/models/sql/compiler.py in execute_sql
cursor.execute(sql, params) ...
/Users/vera/.virtualenvs/app/lib/python2.7/site-packages/debug_toolbar/panels/sql/tracking.py in execute
return self._record(self.cursor.execute, sql, params) ...
/Users/vera/.virtualenvs/app/lib/python2.7/site-packages/debug_toolbar/panels/sql/tracking.py in _record
return method(sql, params) ...
/Users/vera/.virtualenvs/app/lib/python2.7/site-packages/django/db/backends/util.py in execute
return super(CursorDebugWrapper, self).execute(sql, params) ...
/Users/vera/.virtualenvs/app/lib/python2.7/site-packages/django/db/backends/util.py in execute
return self.cursor.execute(sql, params) ...
/Users/vera/.virtualenvs/app/lib/python2.7/site-packages/django/db/utils.py in __exit__
six.reraise(dj_exc_type, dj_exc_value, traceback) ...
/Users/vera/.virtualenvs/app/lib/python2.7/site-packages/django/db/backends/util.py in execute
return self.cursor.execute(sql, params) ...
当有人使用他的 Facebook 帐户注册然后登录时，一切正常。当他使用他的电子邮件注册时出现问题（我正在使用django-registration），所以我们有一个User（但不是UserSocialAuth）的实例，然后我们尝试使用与同一电子邮件地址关联的他的 Facebook 帐户登录。