Optimize the coupling of user social plugin (#950)

Author: wu-clan

backend/app/admin/crud/crud_user.py

@@ -25,7 +25,7 @@
     UpdateUserParam,
 )
 from backend.app.admin.utils.password_security import get_hash_password
-from backend.plugin.oauth2.crud.crud_user_social import user_social_dao
+from backend.utils.import_parse import import_module_cached
 from backend.utils.serializers import select_join_serialize
 from backend.utils.timezone import timezone
 
@@ -299,7 +299,13 @@ async def delete(self, db: AsyncSession, user_id: int) -> int:
         user_role_stmt = delete(user_role).where(user_role.c.user_id == user_id)
         await db.execute(user_role_stmt)
 
-        await user_social_dao.delete_by_user_id(db, user_id)
+        try:
+            user_social = import_module_cached('backend.plugin.oauth2.crud.crud_user_social')
+            user_social_dao = user_social.user_social_dao
+        except (ImportError, AttributeError):
+            pass
+        else:
+            await user_social_dao.delete_by_user_id(db, user_id)
 
         return await self.delete_model(db, user_id)