refactor: part 2 of distinguish between Unique and UniqueIndex (#6822)

migrator/migrator.go

@@ -93,10 +93,6 @@ func (m Migrator) FullDataTypeOf(field *schema.Field) (expr clause.Expr) {
 		expr.SQL += " NOT NULL"
 	}
 
-	if field.Unique {
-		expr.SQL += " UNIQUE"
-	}
-
 	if field.HasDefaultValue && (field.DefaultValueInterface != nil || field.DefaultValue != "") {
 		if field.DefaultValueInterface != nil {
 			defaultStmt := &gorm.Statement{Vars: []interface{}{field.DefaultValueInterface}}
@@ -512,14 +508,6 @@ func (m Migrator) MigrateColumn(value interface{}, field *schema.Field, columnTy
 		}
 	}
 
-	// check unique
-	if unique, ok := columnType.Unique(); ok && unique != (field.Unique || field.UniqueIndex != "") {
-		// not primary key
-		if !field.PrimaryKey {
-			alterColumn = true
-		}
-	}
-
 	// check default value
 	if !field.PrimaryKey {
 		currentDefaultNotNull := field.HasDefaultValue && (field.DefaultValueInterface != nil || !strings.EqualFold(field.DefaultValue, "NULL"))
@@ -548,8 +536,14 @@ func (m Migrator) MigrateColumn(value interface{}, field *schema.Field, columnTy
 		}
 	}
 
-	if alterColumn && !field.IgnoreMigration {
-		return m.DB.Migrator().AlterColumn(value, field.DBName)
+	if alterColumn {
+		if err := m.DB.Migrator().AlterColumn(value, field.DBName); err != nil {
+			return err
+		}
+	}
+
+	if err := m.DB.Migrator().MigrateColumnUnique(value, field, columnType); err != nil {
+		return err
 	}
 
 	return nil