Implement MongoDB database adapter (#29)

* Implement MongoDB adapter using motor

* Add mongo container to build pipeline

* Tidy up dependencies

* Update documentation for MongoDB

* Export MongoDB adapter from db package

* Pass black format

* Update README

fastapi_users/db/__init__.py

@@ -1,4 +1,5 @@
 from fastapi_users.db.base import BaseUserDatabase  # noqa: F401
+from fastapi_users.db.mongodb import MongoDBUserDatabase  # noqa: F401
 from fastapi_users.db.sqlalchemy import (  # noqa: F401
     SQLAlchemyBaseUserTable,
     SQLAlchemyUserDatabase,

fastapi_users/db/mongodb.py

@@ -0,0 +1,40 @@
+from typing import List, Optional
+
+from motor.motor_asyncio import AsyncIOMotorCollection
+
+from fastapi_users.db.base import BaseUserDatabase
+from fastapi_users.models import BaseUserDB
+
+
+class MongoDBUserDatabase(BaseUserDatabase):
+    """
+    Database adapter for MongoDB.
+
+    :param collection: Collection instance from `motor`.
+    """
+
+    collection: AsyncIOMotorCollection
+
+    def __init__(self, collection: AsyncIOMotorCollection):
+        self.collection = collection
+        self.collection.create_index("id", unique=True)
+        self.collection.create_index("email", unique=True)
+
+    async def list(self) -> List[BaseUserDB]:
+        return [BaseUserDB(**user) async for user in self.collection.find()]
+
+    async def get(self, id: str) -> Optional[BaseUserDB]:
+        user = await self.collection.find_one({"id": id})
+        return BaseUserDB(**user) if user else None
+
+    async def get_by_email(self, email: str) -> Optional[BaseUserDB]:
+        user = await self.collection.find_one({"email": email})
+        return BaseUserDB(**user) if user else None
+
+    async def create(self, user: BaseUserDB) -> BaseUserDB:
+        await self.collection.insert_one(user.dict())
+        return user
+
+    async def update(self, user: BaseUserDB) -> BaseUserDB:
+        await self.collection.replace_one({"id": user.id}, user.dict())
+        return user

fastapi_users/db/sqlalchemy.py

@@ -1,4 +1,4 @@
-from typing import List, cast
+from typing import List, Optional, cast
 
 from databases import Database
 from sqlalchemy import Boolean, Column, String, Table
@@ -38,11 +38,11 @@ class SQLAlchemyUserDatabase(BaseUserDatabase):
         query = self.users.select()
         return cast(List[BaseUserDB], await self.database.fetch_all(query))
 
-    async def get(self, id: str) -> BaseUserDB:
+    async def get(self, id: str) -> Optional[BaseUserDB]:
         query = self.users.select().where(self.users.c.id == id)
         return cast(BaseUserDB, await self.database.fetch_one(query))
 
-    async def get_by_email(self, email: str) -> BaseUserDB:
+    async def get_by_email(self, email: str) -> Optional[BaseUserDB]:
         query = self.users.select().where(self.users.c.email == email)
         return cast(BaseUserDB, await self.database.fetch_one(query))