Add helper to parse an enum from query args & use it. (#14956)

The `parse_enum` helper pulls an enum value from the query string
(by delegating down to the parse_string helper with values generated
from the enum).

This is used to pull out "f" and "b" in most places and then we thread
the resulting Direction enum throughout more code.

1 files changed, 9 insertions, 4 deletions

diff --git a/synapse/storage/databases/main/transactions.py b/synapse/storage/databases/main/transactions.py

index f8c6877ee8..6b33d809b6 100644
--- a/synapse/storage/databases/main/transactions.py
+++ b/synapse/storage/databases/main/transactions.py
@@ -19,6 +19,7 @@ from typing import TYPE_CHECKING, Iterable, List, Optional, Tuple, cast
 import attr
 from canonicaljson import encode_canonical_json
 
+from synapse.api.constants import Direction
 from synapse.metrics.background_process_metrics import wrap_as_background_process
 from synapse.storage._base import db_to_json
 from synapse.storage.database import (
@@ -496,7 +497,7 @@ class TransactionWorkerStore(CacheInvalidationWorkerStore):
         limit: int,
         destination: Optional[str] = None,
         order_by: str = DestinationSortOrder.DESTINATION.value,
-        direction: str = "f",
+        direction: Direction = Direction.FORWARDS,
     ) -> Tuple[List[JsonDict], int]:
         """Function to retrieve a paginated list of destinations.
         This will return a json list of destinations and the
@@ -518,7 +519,7 @@ class TransactionWorkerStore(CacheInvalidationWorkerStore):
         ) -> Tuple[List[JsonDict], int]:
             order_by_column = DestinationSortOrder(order_by).value
 
-            if direction == "b":
+            if direction == Direction.BACKWARDS:
                 order = "DESC"
             else:
                 order = "ASC"
@@ -550,7 +551,11 @@ class TransactionWorkerStore(CacheInvalidationWorkerStore):
         )
 
     async def get_destination_rooms_paginate(
-        self, destination: str, start: int, limit: int, direction: str = "f"
+        self,
+        destination: str,
+        start: int,
+        limit: int,
+        direction: Direction = Direction.FORWARDS,
     ) -> Tuple[List[JsonDict], int]:
         """Function to retrieve a paginated list of destination's rooms.
         This will return a json list of rooms and the
@@ -569,7 +574,7 @@ class TransactionWorkerStore(CacheInvalidationWorkerStore):
             txn: LoggingTransaction,
         ) -> Tuple[List[JsonDict], int]:
 
-            if direction == "b":
+            if direction == Direction.BACKWARDS:
                 order = "DESC"
             else:
                 order = "ASC"