Merge pull request #360 from sendyhalim/scope-add-foreignkey

Add Scope.addForeignKey()

README.md

@@ -147,6 +147,13 @@ db.AutoMigrate(&User{}, &Product{}, &Order{})
 // Add index
 db.Model(&User{}).AddIndex("idx_user_name", "name")
 
+// Add foreign key
+// 1st param : foreignkey field
+// 2nd param : destination table(id)
+// 3rd param : ONDELETE
+// 4th param : ONUPDATE
+db.Model(&User{}).AddForeignKey("user_id", "destination_table(id)", "CASCADE", "RESTRICT")
+
 // Multiple column index
 db.Model(&User{}).AddIndex("idx_user_name_age", "name", "age")
 

main.go

@@ -397,6 +397,17 @@ func (s *DB) AddIndex(indexName string, column ...string) *DB {
 	return s
 }
 
+/*
+Add foreign key to the given scope
+
+Example:
+	db.Model(&User{}).AddForeignKey("city_id", "cities(id)", "RESTRICT", "RESTRICT")
+*/
+func (s *DB) AddForeignKey(field string, dest string, onDelete string, onUpdate string) *DB {
+	s.clone().NewScope(s.Value).addForeignKey(field, dest, onDelete, onUpdate)
+	return s
+}
+
 func (s *DB) AddUniqueIndex(indexName string, column ...string) *DB {
 	s.clone().NewScope(s.Value).addIndex(true, indexName, column...)
 	return s

scope_private.go

@@ -633,6 +633,20 @@ func (scope *Scope) addIndex(unique bool, indexName string, column ...string) {
 	scope.Raw(fmt.Sprintf("%s %v ON %v(%v);", sqlCreate, indexName, scope.QuotedTableName(), strings.Join(columns, ", "))).Exec()
 }
 
+func (scope *Scope) addForeignKey(field string, dest string, onDelete string, onUpdate string) {
+	var table string = scope.TableName()
+	var keyName string = fmt.Sprintf("%s_%s_foreign", table, field)
+	var query string = `
+		ALTER TABLE %s
+		ADD CONSTRAINT %s
+		FOREIGN KEY (%s)
+		REFERENCES %s
+		ON DELETE %s
+		ON UPDATE %s;
+	`
+	scope.Raw(fmt.Sprintf(query, table, keyName, field, dest, onDelete, onUpdate)).Exec()
+}
+
 func (scope *Scope) removeIndex(indexName string) {
 	scope.Dialect().RemoveIndex(scope, indexName)
 }