Fix #391: put user creation logic in a importable function

fastapi_users/user.py

@@ -0,0 +1,40 @@
+from typing import Awaitable, Type
+
+from typing_extensions import Protocol
+
+from fastapi_users import models
+from fastapi_users.db import BaseUserDatabase
+from fastapi_users.password import get_password_hash
+
+
+class UserAlreadyExists(Exception):
+    pass
+
+
+class CreateUserProtocol(Protocol):  # pragma: no cover
+    def __call__(
+        self, user: models.BaseUserCreate, safe: bool = False
+    ) -> Awaitable[models.BaseUserDB]:
+        pass
+
+
+def get_create_user(
+    user_db: BaseUserDatabase[models.BaseUserDB],
+    user_db_model: Type[models.BaseUserDB],
+) -> CreateUserProtocol:
+    async def create_user(
+        user: models.BaseUserCreate, safe: bool = False
+    ) -> models.BaseUserDB:
+        existing_user = await user_db.get_by_email(user.email)
+
+        if existing_user is not None:
+            raise UserAlreadyExists()
+
+        hashed_password = get_password_hash(user.password)
+        user_dict = (
+            user.create_update_dict() if safe else user.create_update_dict_superuser()
+        )
+        db_user = user_db_model(**user_dict, hashed_password=hashed_password)
+        return await user_db.create(db_user)
+
+    return create_user