Allow to disable datetime precision, close #13

Author: jinzhu

migrator.go

@@ -192,29 +192,31 @@ func (m Migrator) DropConstraint(value interface{}, name string) error {
 func (m Migrator) ColumnTypes(value interface{}) (columnTypes []gorm.ColumnType, err error) {
 	columnTypes = make([]gorm.ColumnType, 0)
 	err = m.RunWithValue(value, func(stmt *gorm.Statement) error {
-		currentDatabase := m.DB.Migrator().CurrentDatabase()
-		columns, err := m.DB.Raw(
-			"SELECT column_name, is_nullable, data_type, character_maximum_length, "+
-				"numeric_precision, numeric_scale, datetime_precision "+
-				"FROM information_schema.columns WHERE table_schema = ? AND table_name = ?",
-			currentDatabase, stmt.Table).Rows()
+		var (
+			currentDatabase = m.DB.Migrator().CurrentDatabase()
+			columnTypeSQL   = "SELECT column_name, is_nullable, data_type, character_maximum_length, numeric_precision, numeric_scale "
+		)
+
+		if !m.DisableDatetimePrecision {
+			columnTypeSQL += ", datetime_precision "
+		}
+		columnTypeSQL += "FROM information_schema.columns WHERE table_schema = ? AND table_name = ?"
+
+		columns, err := m.DB.Raw(columnTypeSQL, currentDatabase, stmt.Table).Rows()
 		if err != nil {
 			return err
 		}
 		defer columns.Close()
 
 		for columns.Next() {
 			var column Column
-			err = columns.Scan(
-				&column.name,
-				&column.nullable,
-				&column.datatype,
-				&column.maxlen,
-				&column.precision,
-				&column.scale,
-				&column.datetimeprecision,
-			)
-			if err != nil {
+			var values = []interface{}{&column.name, &column.nullable, &column.datatype, &column.maxlen, &column.precision, &column.scale}
+
+			if !m.DisableDatetimePrecision {
+				values = append(values, &column.datetimeprecision)
+			}
+
+			if err = columns.Scan(values...); err != nil {
 				return err
 			}
 			columnTypes = append(columnTypes, column)

mysql.go

@@ -22,6 +22,7 @@ type Config struct {
 	Conn                      gorm.ConnPool
 	SkipInitializeWithVersion bool
 	DefaultStringSize         uint
+	DefaultDatetimePrecision  *int
 	DisableDatetimePrecision  bool
 	DontSupportRenameIndex    bool
 	DontSupportRenameColumn   bool
@@ -56,6 +57,11 @@ func (dialector Dialector) Initialize(db *gorm.DB) (err error) {
 		dialector.DriverName = "mysql"
 	}
 
+	if dialector.DefaultDatetimePrecision == nil {
+		var defaultDatetimePrecision = 3
+		dialector.DefaultDatetimePrecision = &defaultDatetimePrecision
+	}
+
 	if dialector.Conn != nil {
 		db.ConnPool = dialector.Conn
 	} else {
@@ -260,14 +266,12 @@ func (dialector Dialector) DataTypeOf(field *schema.Field) string {
 	case schema.Time:
 		precision := ""
 
-		if !dialector.DisableDatetimePrecision {
-			if field.Precision == 0 {
-				field.Precision = 3
-			}
+		if !dialector.DisableDatetimePrecision && field.Precision == 0 {
+			field.Precision = *dialector.DefaultDatetimePrecision
+		}
 
-			if field.Precision > 0 {
-				precision = fmt.Sprintf("(%d)", field.Precision)
-			}
+		if field.Precision > 0 {
+			precision = fmt.Sprintf("(%d)", field.Precision)
 		}
 
 		if field.NotNull || field.PrimaryKey {