Some Tweaks for Preload Many2Many, Add tests with inline conditions

join_table_handler.go

@@ -13,10 +13,9 @@ type JoinTableHandlerInterface interface {
 	Add(handler JoinTableHandlerInterface, db *DB, source interface{}, destination interface{}) error
 	Delete(handler JoinTableHandlerInterface, db *DB, sources ...interface{}) error
 	JoinWith(handler JoinTableHandlerInterface, db *DB, source interface{}) *DB
-	PreloadWithJoin(handler JoinTableHandlerInterface, db *DB, source interface{}, conditions ...interface{}) *DB
+	PreloadWithJoin(handler JoinTableHandlerInterface, db *DB, source interface{}) *DB
 	SourceForeignKeys() []JoinTableForeignKey
 	DestinationForeignKeys() []JoinTableForeignKey
-	DestinationType() reflect.Type
 }
 
 type JoinTableForeignKey struct {
@@ -139,8 +138,8 @@ func (s JoinTableHandler) JoinWith(handler JoinTableHandlerInterface, db *DB, so
 	var queryConditions []string
 	var values []interface{}
 	if s.Source.ModelType == modelType {
-		for _, foreignKey := range s.Destination.ForeignKeys {
 		destinationTableName := db.NewScope(reflect.New(s.Destination.ModelType).Interface()).QuotedTableName()
+		for _, foreignKey := range s.Destination.ForeignKeys {
 			joinConditions = append(joinConditions, fmt.Sprintf("%v.%v = %v.%v", quotedTable, scope.Quote(foreignKey.DBName), destinationTableName, scope.Quote(foreignKey.AssociationDBName)))
 		}
 
@@ -156,7 +155,7 @@ func (s JoinTableHandler) JoinWith(handler JoinTableHandlerInterface, db *DB, so
 	}
 }
 
-func (s JoinTableHandler) PreloadWithJoin(handler JoinTableHandlerInterface, db *DB, source interface{}, conditions ...interface{}) *DB {
+func (s JoinTableHandler) PreloadWithJoin(handler JoinTableHandlerInterface, db *DB, source interface{}) *DB {
 	quotedTable := handler.Table(db)
 
 	scope := db.NewScope(source)
@@ -165,8 +164,8 @@ func (s JoinTableHandler) PreloadWithJoin(handler JoinTableHandlerInterface, db
 	var queryConditions []string
 	var values []interface{}
 	if s.Source.ModelType == modelType {
+		destinationTableName := db.NewScope(reflect.New(s.Destination.ModelType).Interface()).QuotedTableName()
 		for _, foreignKey := range s.Destination.ForeignKeys {
-			destinationTableName := db.NewScope(reflect.New(s.Destination.ModelType).Interface()).inlineCondition(conditions...).QuotedTableName()
 			joinConditions = append(joinConditions, fmt.Sprintf("%v.%v = %v.%v", quotedTable, scope.Quote(foreignKey.DBName), destinationTableName, scope.Quote(foreignKey.AssociationDBName)))
 		}
 
@@ -179,11 +178,6 @@ func (s JoinTableHandler) PreloadWithJoin(handler JoinTableHandlerInterface, db
 			queryConditions = append(queryConditions, condString)
 		}
 
-		if len(conditions) > 0 {
-			queryConditions = append(queryConditions, toString(conditions[0]))
-			values = append(values, conditions[1:]...)
-		}
-
 		return db.Joins(fmt.Sprintf("INNER JOIN %v ON %v", quotedTable, strings.Join(joinConditions, " AND "))).
 			Where(strings.Join(queryConditions, " AND "), values...)
 	} else {
@@ -191,7 +185,3 @@ func (s JoinTableHandler) PreloadWithJoin(handler JoinTableHandlerInterface, db
 		return db
 	}
 }
-
-func (s JoinTableHandler) DestinationType() reflect.Type {
-	return s.Destination.ModelType
-}

preload.go

@@ -195,14 +195,16 @@ func (scope *Scope) handleHasManyToManyPreload(field *Field, conditions []interf
 	relation := field.Relationship
 
 	joinTableHandler := relation.JoinTableHandler
-	destType := joinTableHandler.DestinationType()
+	destType := field.StructField.Struct.Type.Elem()
-
+	var isPtr bool
-	db := scope.NewDB().Table(scope.db.NewScope(reflect.New(destType).Elem().Interface()).TableName())
+	if destType.Kind() == reflect.Ptr {
+		isPtr = true
+		destType = destType.Elem()
+	}
 
 	var destKeys []string
 	var sourceKeys []string
-
+	var linkHash = make(map[string][]string)
-	linkHash := make(map[string][]string)
 
 	for _, key := range joinTableHandler.DestinationForeignKeys() {
 		destKeys = append(destKeys, key.DBName)
@@ -213,7 +215,13 @@ func (scope *Scope) handleHasManyToManyPreload(field *Field, conditions []interf
 	}
 
 	results := reflect.New(field.Struct.Type).Elem()
-	rows, err := joinTableHandler.PreloadWithJoin(joinTableHandler, db, scope.Value, conditions...).Rows()
+
+	db := scope.NewDB().Table(scope.New(reflect.New(destType).Interface()).TableName())
+	preloadJoinDB := joinTableHandler.PreloadWithJoin(joinTableHandler, db, scope.Value)
+	if len(conditions) > 0 {
+		preloadJoinDB = preloadJoinDB.Where(conditions[0], conditions[1:]...)
+	}
+	rows, err := preloadJoinDB.Rows()
 
 	if scope.Err(err) != nil {
 		return
@@ -264,8 +272,11 @@ func (scope *Scope) handleHasManyToManyPreload(field *Field, conditions []interf
 			linkHash[toString(sourceKey)] = append(linkHash[toString(sourceKey)], toString(destKey))
 		}
 
+		if isPtr {
+			results = reflect.Append(results, elem.Addr())
+		} else {
 			results = reflect.Append(results, elem)
-
+		}
 	}
 
 	if scope.IndirectValue().Kind() == reflect.Slice {

preload_test.go

@@ -612,7 +612,7 @@ func TestManyToManyPreload(t *testing.T) {
 		Level2 struct {
 			ID      uint `gorm:"primary_key;"`
 			Value   string
-			Level1s []Level1 `gorm:"many2many:levels;"`
+			Level1s []*Level1 `gorm:"many2many:levels;"`
 		}
 	)
 
@@ -623,7 +623,7 @@ func TestManyToManyPreload(t *testing.T) {
 		panic(err)
 	}
 
-	want := Level2{Value: "Bob", Level1s: []Level1{
+	want := Level2{Value: "Bob", Level1s: []*Level1{
 		{Value: "ru"},
 		{Value: "en"},
 	}}
@@ -631,7 +631,7 @@ func TestManyToManyPreload(t *testing.T) {
 		panic(err)
 	}
 
-	want2 := Level2{Value: "Tom", Level1s: []Level1{
+	want2 := Level2{Value: "Tom", Level1s: []*Level1{
 		{Value: "zh"},
 		{Value: "de"},
 	}}
@@ -665,6 +665,22 @@ func TestManyToManyPreload(t *testing.T) {
 	if !reflect.DeepEqual(got3, []Level2{got, got2}) {
 		t.Errorf("got %s; want %s", toJSONString(got3), toJSONString([]Level2{got, got2}))
 	}
+
+	var got4 []Level2
+	if err := DB.Preload("Level1s", "value IN (?)", []string{"zh", "ru"}).Find(&got4, "value IN (?)", []string{"Bob", "Tom"}).Error; err != nil {
+		panic(err)
+	}
+
+	var ruLevel1 Level1
+	var zhLevel1 Level1
+	DB.First(&ruLevel1, "value = ?", "ru")
+	DB.First(&zhLevel1, "value = ?", "zh")
+
+	got.Level1s = []*Level1{&ruLevel1}
+	got2.Level1s = []*Level1{&zhLevel1}
+	if !reflect.DeepEqual(got4, []Level2{got, got2}) {
+		t.Errorf("got %s; want %s", toJSONString(got4), toJSONString([]Level2{got, got2}))
+	}
 }
 
 func toJSONString(v interface{}) []byte {