Fix record sorting order (NULLS FIRST/LAST)

store/mysql/mysql.go

@@ -43,6 +43,7 @@ func Connect(ctx context.Context, dsn string) (store.Storer, error) {
 	cfg.ErrorHandler = errorHandler
 	cfg.UpsertBuilder = UpsertBuilder
 	cfg.CastModuleFieldToColumnType = fieldToColumnTypeCaster
+	cfg.SqlSortHandler = SqlSortHandler
 
 	if s.Store, err = rdbms.Connect(ctx, cfg); err != nil {
 		return nil, err

store/mysql/sql_order.go

@@ -0,0 +1,11 @@
+package mysql
+
+import "fmt"
+
+func SqlSortHandler(exp string, desc bool) string {
+	if desc {
+		return fmt.Sprintf("%s DESC", exp)
+	} else {
+		return fmt.Sprintf("%s ASC", exp)
+	}
+}

store/rdbms/compose_records.go

@@ -321,8 +321,6 @@ func (s Store) composeRecordsSorter(m *types.Module, q squirrel.SelectBuilder, s
 		if sortable[c.Column] {
 			sqlSort[i] = c.Column
 		} else if f := m.Fields.FindByName(c.Column); f != nil {
-			//sqlSort[i] = fmt.Sprintf("%s%s.value", composeRecordValueAliasPfx, sort[i].Column)
-			// sqlSort[i] = fmt.Sprintf("COALESCE(%s%s.value, '')", composeRecordValueAliasPfx + sort[i].Column)
 			sqlSort[i], err = s.config.CastModuleFieldToColumnType(f, c.Column)
 		} else {
 			err = fmt.Errorf("could not sort by unknown column: %s", c.Column)
@@ -332,9 +330,8 @@ func (s Store) composeRecordsSorter(m *types.Module, q squirrel.SelectBuilder, s
 			return q, err
 		}
 
-		if sort[i].Descending {
-			sqlSort[i] += " DESC"
-		}
+		// Apply proper sorting param
+		sqlSort[i] = s.config.SqlSortHandler(sqlSort[i], sort[i].Descending)
 	}
 
 	return q.OrderBy(sqlSort...), nil

store/rdbms/rdbms.go

@@ -445,6 +445,14 @@ func setOrderBy(q squirrel.SelectBuilder, sort filter.SortExprSet, ss ...string)
 	return q.OrderBy(sqlSort...), nil
 }
 
+func SqlSortHandler(exp string, desc bool) string {
+	if desc {
+		return fmt.Sprintf("%s DESC NULLS LAST", exp)
+	} else {
+		return fmt.Sprintf("%s ASC NULLS FIRST", exp)
+	}
+}
+
 // TxNoRetry - Transaction retry handler
 //
 // Only returns false so transactions will never retry

store/rdbms/rdbms_config.go

@@ -111,6 +111,11 @@ type (
 		// Functions are used in filters and aggregations
 		SqlFunctionHandler func(f ql.Function) (ql.ASTNode, error)
 
+		// SqlSortHandler handles construction of sorting expression
+		//
+		// MySQL does not support NULLS FIRST/LAST and without it sorts nulls differently then Postgres/SQLite
+		SqlSortHandler func(exp string, desc bool) string
+
 		CastModuleFieldToColumnType func(ModuleFieldTypeDetector, string) (string, error)
 	}
 )
@@ -184,6 +189,10 @@ func (c *Config) SetDefaults() {
 	if c.TriggerHandlers == nil {
 		c.TriggerHandlers = TriggerHandlers{}
 	}
+
+	if c.SqlSortHandler == nil {
+		c.SqlSortHandler = SqlSortHandler
+	}
 }
 
 // ParseExtra parses extra params (params starting with *)