ensure multiple index via db interface

setup.go

@@ -9,10 +9,22 @@ import (
 )
 
 // EnsureIndex ensured mongodb index reflecting model struct index tag
-func (db *MgoDatabase) EnsureIndex(m ModelInterface) error {
+func (db *MgoDatabase) EnsureIndex(m ModelInterface, index ...Index) error {
 	colName := GetCollectionName(m)
 	col := db.C(colName)
 
+	if len(index) > 0 {
+		// only ensure given index
+		for _, i := range index {
+			err := col.EnsureIndex(i)
+			if err != nil {
+				return err
+			}
+		}
+		return nil
+	}
+
+	// ensure index by struct fields
 	mType := reflect.TypeOf(m)
 
 	textFields := []string{}

types.go

@@ -22,9 +22,9 @@ type Session interface {
 
 type Database interface {
 	Session() Session
-	C(name string) Collection
+	// C(name string) Collection
 	Name() string
-	EnsureIndex(m ModelInterface) error
+	EnsureIndex(m ModelInterface, index ...Index) error
 	ValidateObject(m ModelInterface, changes bson.M) error
 	ReadDocument(m ModelInterface, selector bson.M) error
 	CreateDocument(m ModelInterface) error