Support Multi primary keys

association.go

@@ -52,12 +52,12 @@ func (association *Association) getPrimaryKeys(values ...interface{}) []interfac
 		reflectValue := reflect.Indirect(reflect.ValueOf(value))
 		if reflectValue.Kind() == reflect.Slice {
 			for i := 0; i < reflectValue.Len(); i++ {
-				if primaryField := scope.New(reflectValue.Index(i).Interface()).PrimaryKeyField(); !primaryField.IsBlank {
+				if primaryField := scope.New(reflectValue.Index(i).Interface()).PrimaryField(); !primaryField.IsBlank {
 					primaryKeys = append(primaryKeys, primaryField.Field.Interface())
 				}
 			}
 		} else if reflectValue.Kind() == reflect.Struct {
-			if primaryField := scope.New(value).PrimaryKeyField(); !primaryField.IsBlank {
+			if primaryField := scope.New(value).PrimaryField(); !primaryField.IsBlank {
 				primaryKeys = append(primaryKeys, primaryField.Field.Interface())
 			}
 		}
@@ -81,7 +81,7 @@ func (association *Association) Delete(values ...interface{}) *Association {
 				leftValues := reflect.Zero(association.Field.Field.Type())
 				for i := 0; i < association.Field.Field.Len(); i++ {
 					value := association.Field.Field.Index(i)
-					if primaryField := association.Scope.New(value.Interface()).PrimaryKeyField(); primaryField != nil {
+					if primaryField := association.Scope.New(value.Interface()).PrimaryField(); primaryField != nil {
 						var included = false
 						for _, primaryKey := range primaryKeys {
 							if equalAsString(primaryKey, primaryField.Field.Interface()) {

callback_create.go

@@ -34,7 +34,7 @@ func Create(scope *Scope) {
 		}
 
 		returningKey := "*"
-		primaryField := scope.PrimaryKeyField()
+		primaryField := scope.PrimaryField()
 		if primaryField != nil {
 			returningKey = scope.Quote(primaryField.DBName)
 		}

embedded_struct_test.go

@@ -36,7 +36,7 @@ func TestSaveAndQueryEmbeddedStruct(t *testing.T) {
 		t.Errorf("embedded struct's value should be scanned correctly")
 	}
 
-	if DB.NewScope(&HNPost{}).PrimaryKeyField() == nil {
+	if DB.NewScope(&HNPost{}).PrimaryField() == nil {
 		t.Errorf("primary key with embedded struct should works")
 	}
 

main.go

@@ -431,7 +431,7 @@ func (s *DB) Association(column string) *Association {
 	var err error
 	scope := s.clone().NewScope(s.Value)
 
-	if primaryField := scope.PrimaryKeyField(); primaryField.IsBlank {
+	if primaryField := scope.PrimaryField(); primaryField.IsBlank {
 		err = errors.New("primary key can't be nil")
 	} else {
 		if field, ok := scope.FieldByName(column); ok {

model_struct.go

@@ -12,10 +12,10 @@ import (
 )
 
 type ModelStruct struct {
-	PrimaryKeyField *StructField
-	StructFields    []*StructField
-	ModelType       reflect.Type
-	TableName       string
+	PrimaryFields []*StructField
+	StructFields  []*StructField
+	ModelType     reflect.Type
+	TableName     string
 }
 
 type StructField struct {
@@ -131,7 +131,7 @@ func (scope *Scope) GetModelStruct() *ModelStruct {
 				gormSettings := parseTagSetting(field.Tag.Get("gorm"))
 				if _, ok := gormSettings["PRIMARY_KEY"]; ok {
 					field.IsPrimaryKey = true
-					modelStruct.PrimaryKeyField = field
+					modelStruct.PrimaryFields = append(modelStruct.PrimaryFields, field)
 				}
 
 				if _, ok := sqlSettings["DEFAULT"]; ok {
@@ -240,7 +240,7 @@ func (scope *Scope) GetModelStruct() *ModelStruct {
 							toField.Names = append([]string{fieldStruct.Name}, toField.Names...)
 							modelStruct.StructFields = append(modelStruct.StructFields, toField)
 							if toField.IsPrimaryKey {
-								modelStruct.PrimaryKeyField = toField
+								modelStruct.PrimaryFields = append(modelStruct.PrimaryFields, toField)
 							}
 						}
 						continue
@@ -277,9 +277,9 @@ func (scope *Scope) GetModelStruct() *ModelStruct {
 			}
 
 			if field.IsNormal {
-				if modelStruct.PrimaryKeyField == nil && field.DBName == "id" {
+				if len(modelStruct.PrimaryFields) == 0 && field.DBName == "id" {
 					field.IsPrimaryKey = true
-					modelStruct.PrimaryKeyField = field
+					modelStruct.PrimaryFields = append(modelStruct.PrimaryFields, field)
 				}
 
 				if scope.db != nil {

preload.go

@@ -29,8 +29,8 @@ func Preload(scope *Scope) {
 				if field.Name == key && field.Relationship != nil {
 					results := makeSlice(field.Struct.Type)
 					relation := field.Relationship
-					primaryName := scope.PrimaryKeyField().Name
-					associationPrimaryKey := scope.New(results).PrimaryKeyField().Name
+					primaryName := scope.PrimaryField().Name
+					associationPrimaryKey := scope.New(results).PrimaryField().Name
 
 					switch relation.Kind {
 					case "has_one":

scope.go

@@ -109,16 +109,21 @@ func (scope *Scope) HasError() bool {
 	return scope.db.Error != nil
 }
 
-func (scope *Scope) PrimaryKeyField() *Field {
-	if field := scope.GetModelStruct().PrimaryKeyField; field != nil {
-		return scope.Fields()[field.DBName]
+func (scope *Scope) PrimaryField() *Field {
+	if primaryFields := scope.GetModelStruct().PrimaryFields; len(primaryFields) > 0 {
+		if len(primaryFields) > 1 {
+			if field, ok := scope.Fields()["id"]; ok {
+				return field
+			}
+		}
+		return scope.Fields()[primaryFields[0].DBName]
 	}
 	return nil
 }
 
 // PrimaryKey get the primary key's column name
 func (scope *Scope) PrimaryKey() string {
-	if field := scope.PrimaryKeyField(); field != nil {
+	if field := scope.PrimaryField(); field != nil {
 		return field.DBName
 	}
 	return ""
@@ -126,13 +131,13 @@ func (scope *Scope) PrimaryKey() string {
 
 // PrimaryKeyZero check the primary key is blank or not
 func (scope *Scope) PrimaryKeyZero() bool {
-	field := scope.PrimaryKeyField()
+	field := scope.PrimaryField()
 	return field == nil || field.IsBlank
 }
 
 // PrimaryKeyValue get the primary key's value
 func (scope *Scope) PrimaryKeyValue() interface{} {
-	if field := scope.PrimaryKeyField(); field != nil && field.Field.IsValid() {
+	if field := scope.PrimaryField(); field != nil && field.Field.IsValid() {
 		return field.Field.Interface()
 	}
 	return 0

scope_private.go

@@ -447,7 +447,7 @@ func (scope *Scope) createJoinTable(field *StructField) {
 		joinTableHandler := scope.db.GetJoinTableHandler(relationship.JoinTable)
 		joinTable := joinTableHandler.Table(scope.db, relationship)
 		if !scope.Dialect().HasTable(scope, joinTable) {
-			primaryKeySqlType := scope.Dialect().SqlTag(scope.PrimaryKeyField().Field, 255)
+			primaryKeySqlType := scope.Dialect().SqlTag(scope.PrimaryField().Field, 255)
 			scope.Err(scope.NewDB().Exec(fmt.Sprintf("CREATE TABLE %v (%v)",
 				scope.Quote(joinTable),
 				strings.Join([]string{