Update migrator.go

migrator/migrator.go

@@ -424,13 +424,29 @@ func (m Migrator) MigrateColumn(value interface{}, field *schema.Field, columnTy
 	fullDataType := strings.TrimSpace(strings.ToLower(m.DB.Migrator().FullDataTypeOf(field).SQL))
 	realDataType := strings.ToLower(columnType.DatabaseTypeName())
 
-	alterColumn := false
+	var (
+		alterColumn, isSameType bool
+	)
 
+	if !field.PrimaryKey {
 		// check type
-	if !field.PrimaryKey && !strings.HasPrefix(fullDataType, realDataType) {
+		if !strings.HasPrefix(fullDataType, realDataType) {
-		alterColumn = true
+			// check type aliases
+			aliases := m.DB.Migrator().GetTypeAliases(realDataType)
+			for _, alias := range aliases {
+				if strings.HasPrefix(fullDataType, alias) {
+					isSameType = true
+					break
+				}
 			}
 
+			if !isSameType {
+				alterColumn = true
+			}
+		}
+	}
+
+	if !isSameType {
 		// check size
 		if length, ok := columnType.Length(); length != int64(field.Size) {
 			if length > 0 && field.Size > 0 {
@@ -452,6 +468,7 @@ func (m Migrator) MigrateColumn(value interface{}, field *schema.Field, columnTy
 				alterColumn = true
 			}
 		}
+	}
 
 	// check nullable
 	if nullable, ok := columnType.Nullable(); ok && nullable == field.NotNull {
@@ -471,17 +488,19 @@ func (m Migrator) MigrateColumn(value interface{}, field *schema.Field, columnTy
 
 	// check default value
 	if !field.PrimaryKey {
+		currentDefaultNotNull := field.HasDefaultValue && !strings.EqualFold(field.DefaultValue, "NULL")
 		dv, dvNotNull := columnType.DefaultValue()
-		if dvNotNull && field.DefaultValueInterface == nil {
+		if dvNotNull && !currentDefaultNotNull {
 			// defalut value -> null
 			alterColumn = true
-		} else if !dvNotNull && field.DefaultValueInterface != nil {
+		} else if !dvNotNull && currentDefaultNotNull {
 			// null -> default value
 			alterColumn = true
-		} else if dv != field.DefaultValue {
+		} else if (field.GORMDataType != schema.Time && dv != field.DefaultValue) ||
+			(field.GORMDataType == schema.Time && !strings.EqualFold(strings.TrimSuffix(dv, "()"), strings.TrimSuffix(field.DefaultValue, "()"))) {
 			// default value not equal
 			// not both null
-			if !(field.DefaultValueInterface == nil && !dvNotNull) {
+			if currentDefaultNotNull || dvNotNull {
 				alterColumn = true
 			}
 		}
@@ -496,7 +515,7 @@ func (m Migrator) MigrateColumn(value interface{}, field *schema.Field, columnTy
 	}
 
 	if alterColumn && !field.IgnoreMigration {
-		return m.DB.Migrator().AlterColumn(value, field.Name)
+		return m.DB.Migrator().AlterColumn(value, field.DBName)
 	}
 
 	return nil
@@ -881,3 +900,8 @@ func (m Migrator) CurrentTable(stmt *gorm.Statement) interface{} {
 func (m Migrator) GetIndexes(dst interface{}) ([]gorm.Index, error) {
 	return nil, errors.New("not support")
 }
+
+// GetTypeAliases return database type aliases
+func (m Migrator) GetTypeAliases(databaseTypeName string) []string {
+	return nil
+}