Return None from fetch_one if no results match

Author: lovelydinosaur

databases/backends/mysql.py

@@ -105,6 +105,8 @@ async def fetch_one(self, query: ClauseElement) -> typing.Optional[typing.Mappin
         try:
             await cursor.execute(query, args)
             row = await cursor.fetchone()
+            if row is None:
+                return None
             metadata = ResultMetaData(context, cursor.description)
             return RowProxy(metadata, row, metadata._processors, metadata._keymap)
         finally:

databases/backends/postgres.py

@@ -121,6 +121,8 @@ async def fetch_one(self, query: ClauseElement) -> typing.Optional[typing.Mappin
         assert self._connection is not None, "Connection is not acquired"
         query, args, result_columns = self._compile(query)
         row = await self._connection.fetchrow(query, *args)
+        if row is None:
+            return None
         return Record(row, result_columns, self._dialect)
 
     async def execute(self, query: ClauseElement, values: dict = None) -> typing.Any:

databases/backends/sqlite.py

@@ -97,6 +97,8 @@ async def fetch_one(self, query: ClauseElement) -> typing.Optional[typing.Mappin
 
         async with self._connection.execute(query, args) as cursor:
             row = await cursor.fetchone()
+            if row is None:
+                return None
             metadata = ResultMetaData(context, cursor.description)
             return RowProxy(metadata, row, metadata._processors, metadata._keymap)