Pagination probably works now

syncapi/routing/relations.go

@@ -75,15 +75,9 @@ func Relations(req *http.Request, device *api.Device, syncDB storage.Database, r
 	var succeeded bool
 	defer sqlutil.EndTransactionWithCheck(snapshot, &succeeded, &err)
 
-	if to == 0 {
-		if to, err = snapshot.MaxStreamPositionForRelations(req.Context()); err != nil {
-			return util.ErrorResponse(err)
-		}
-	}
-
 	res := &RelationsResponse{}
 	res.Chunk, res.PrevBatch, res.NextBatch, err = snapshot.RelationsFor(
-		req.Context(), roomID, eventID, relType, eventType, from, to, limit,
+		req.Context(), roomID, eventID, relType, eventType, from, to, dir == "b", limit,
 	)
 	if err != nil {
 		return util.ErrorResponse(err)

syncapi/storage/interface.go

@@ -108,7 +108,7 @@ type DatabaseTransaction interface {
 	GetUserUnreadNotificationCountsForRooms(ctx context.Context, userID string, roomIDs map[string]string) (map[string]*eventutil.NotificationData, error)
 	GetPresence(ctx context.Context, userID string) (*types.PresenceInternal, error)
 	PresenceAfter(ctx context.Context, after types.StreamPosition, filter gomatrixserverlib.EventFilter) (map[string]*types.PresenceInternal, error)
-	RelationsFor(ctx context.Context, roomID, eventID, relType, eventType string, from, to types.StreamPosition, limit int) (clientEvents []gomatrixserverlib.ClientEvent, prevBatch, nextBatch string, err error)
+	RelationsFor(ctx context.Context, roomID, eventID, relType, eventType string, from, to types.StreamPosition, backwards bool, limit int) (clientEvents []gomatrixserverlib.ClientEvent, prevBatch, nextBatch string, err error)
 }
 
 type Database interface {

syncapi/storage/postgres/relations_table.go

@@ -50,12 +50,12 @@ const deleteRelationSQL = "" +
 
 const selectRelationsInRangeSQL = "" +
 	"SELECT id, room_id, child_event_id, rel_type FROM syncapi_relations" +
-	" WHERE room_id = $1 AND event_id = $2 AND id > $3 AND id <= $4" +
+	" WHERE room_id = $1 AND event_id = $2 AND id >= $3 AND id <= $4" +
 	" ORDER BY id DESC LIMIT $5"
 
 const selectRelationsByTypeInRangeSQL = "" +
 	"SELECT id, room_id, child_event_id, rel_type FROM syncapi_relations" +
-	" WHERE room_id = $1 AND event_id = $2 AND rel_type = $3 AND id > $4 AND id <= $5" +
+	" WHERE room_id = $1 AND event_id = $2 AND rel_type = $3 AND id >= $4 AND id <= $5" +
 	" ORDER BY id DESC LIMIT $6"
 
 const selectMaxRelationIDSQL = "" +

syncapi/storage/shared/storage_sync.go

@@ -595,7 +595,7 @@ func (d *DatabaseTransaction) MaxStreamPositionForRelations(ctx context.Context)
 	return types.StreamPosition(id), err
 }
 
-func (d *DatabaseTransaction) RelationsFor(ctx context.Context, roomID, eventID, relType, eventType string, from, to types.StreamPosition, limit int) (
+func (d *DatabaseTransaction) RelationsFor(ctx context.Context, roomID, eventID, relType, eventType string, from, to types.StreamPosition, backwards bool, limit int) (
 	clientEvents []gomatrixserverlib.ClientEvent, prevBatch, nextBatch string, err error,
 ) {
 	clientEvents = []gomatrixserverlib.ClientEvent{}
@@ -603,7 +603,16 @@ func (d *DatabaseTransaction) RelationsFor(ctx context.Context, roomID, eventID,
 	r := types.Range{
 		From:      from,
 		To:        to,
-		Backwards: from > to,
+		Backwards: backwards,
+	}
+	if r.To == 0 && !backwards {
+		if r.To, err = d.MaxStreamPositionForRelations(ctx); err != nil {
+			return nil, "", "", fmt.Errorf("d.MaxStreamPositionForRelations: %w", err)
+		}
+	} else if r.From == 0 && backwards {
+		if r.From, err = d.MaxStreamPositionForRelations(ctx); err != nil {
+			return nil, "", "", fmt.Errorf("d.MaxStreamPositionForRelations: %w", err)
+		}
 	}
 
 	// First up look up any relations from the database. We add one to the limit here
@@ -633,7 +642,7 @@ func (d *DatabaseTransaction) RelationsFor(ctx context.Context, roomID, eventID,
 	// Otherwise, let's try and work out what sensible prev_batch and next_batch values
 	// could be.
 	if from > 0 {
-		prevBatch = fmt.Sprintf("%d", entries[0].Position-1)
+		prevBatch = fmt.Sprintf("%d", r.Low()-1)
 	}
 	if len(entries) > limit {
 		nextBatch = fmt.Sprintf("%d", entries[len(entries)-1].Position)

syncapi/storage/sqlite3/relations_table.go

@@ -48,12 +48,12 @@ const deleteRelationSQL = "" +
 
 const selectRelationsInRangeSQL = "" +
 	"SELECT id, room_id, child_event_id, rel_type FROM syncapi_relations" +
-	" WHERE room_id = $1 AND event_id = $2 AND id > $3 AND id <= $4" +
+	" WHERE room_id = $1 AND event_id = $2 AND id >= $3 AND id <= $4" +
 	" ORDER BY id DESC LIMIT $5"
 
 const selectRelationsByTypeInRangeSQL = "" +
 	"SELECT id, room_id, child_event_id, rel_type FROM syncapi_relations" +
-	" WHERE room_id = $1 AND event_id = $2 AND rel_type = $3 AND id > $4 AND id <= $5" +
+	" WHERE room_id = $1 AND event_id = $2 AND rel_type = $3 AND id >= $4 AND id <= $5" +
 	" ORDER BY id DESC LIMIT $6"
 
 const selectMaxRelationIDSQL = "" +