Fix file info index batch (#17525)

store/sqlstore/file_info_store.go

@@ -101,7 +101,7 @@ func (fs SqlFileInfoStore) Save(info *model.FileInfo) (*model.FileInfo, error) {
 
 func (fs SqlFileInfoStore) GetByIds(ids []string) ([]*model.FileInfo, error) {
 	query := fs.getQueryBuilder().
-		Select(append(fs.queryFields, "P.ChannelId")...).
+		Select(append(fs.queryFields, "COALESCE(P.ChannelId, '') as ChannelId")...).
 		From("FileInfo").
 		LeftJoin("Posts as P ON FileInfo.PostId=P.Id").
 		Where(sq.Eq{"FileInfo.Id": ids}).
@@ -441,7 +441,7 @@ func (fs SqlFileInfoStore) Search(paramsList []*model.SearchParams, userId, team
 		return nil, err
 	}
 	query := fs.getQueryBuilder().
-		Select(append(fs.queryFields, "P.ChannelId as ChannelId")...).
+		Select(append(fs.queryFields, "Coalesce(P.ChannelId, '') AS ChannelId")...).
 		From("FileInfo").
 		LeftJoin("Posts as P ON FileInfo.PostId=P.Id").
 		LeftJoin("Channels as C ON C.Id=P.ChannelId").
@@ -627,7 +627,7 @@ func (fs SqlFileInfoStore) CountAll() (int64, error) {
 func (fs SqlFileInfoStore) GetFilesBatchForIndexing(startTime, endTime int64, limit int) ([]*model.FileForIndexing, error) {
 	var files []*model.FileForIndexing
 	sql, args, _ := fs.getQueryBuilder().
-		Select(append(fs.queryFields, "p.ChannelId")...).
+		Select(append(fs.queryFields, "Coalesce(p.ChannelId, '') AS ChannelId")...).
 		From("FileInfo").
 		LeftJoin("Posts AS p ON FileInfo.PostId = p.Id").
 		Where(sq.GtOrEq{"FileInfo.CreateAt": startTime}).