Make association replace works

association.go

@@ -57,9 +57,10 @@ func (association *Association) Append(values ...interface{}) *Association {
 	return association.err(scope.db.Error)
 }
 
-func (association *Association) Delete(values ...interface{}) *Association {
+func (association *Association) getPrimaryKeys(values ...interface{}) []interface{} {
 	primaryKeys := []interface{}{}
 	scope := association.Scope
+
 	for _, value := range values {
 		reflectValue := reflect.ValueOf(value)
 		if reflectValue.Kind() == reflect.Ptr {
@@ -81,6 +82,11 @@ func (association *Association) Delete(values ...interface{}) *Association {
 			}
 		}
 	}
+	return primaryKeys
+}
+
+func (association *Association) Delete(values ...interface{}) *Association {
+	primaryKeys := association.getPrimaryKeys(values...)
 
 	if len(primaryKeys) == 0 {
 		association.err(errors.New("no primary key found"))
@@ -88,8 +94,8 @@ func (association *Association) Delete(values ...interface{}) *Association {
 		relationship := association.Field.Relationship
 		// many to many
 		if relationship.kind == "many_to_many" {
-			whereSql := fmt.Sprintf("%v.%v IN (?)", relationship.joinTable, scope.Quote(ToSnake(relationship.associationForeignKey)))
+			whereSql := fmt.Sprintf("%v.%v IN (?)", relationship.joinTable, association.Scope.Quote(ToSnake(relationship.associationForeignKey)))
-			scope.db.Table(relationship.joinTable).Where(whereSql, primaryKeys).Delete("")
+			association.Scope.db.Model("").Table(relationship.joinTable).Where(whereSql, primaryKeys).Delete("")
 		} else {
 			association.err(errors.New("delete only support many to many"))
 		}
@@ -97,7 +103,38 @@ func (association *Association) Delete(values ...interface{}) *Association {
 	return association
 }
 
-func (association *Association) Replace(values interface{}) *Association {
+func (association *Association) Replace(values ...interface{}) *Association {
+	relationship := association.Field.Relationship
+	scope := association.Scope
+	if relationship.kind == "many_to_many" {
+		field := scope.IndirectValue().FieldByName(association.Column)
+
+		oldPrimaryKeys := association.getPrimaryKeys(field.Interface())
+		association.Append(values...)
+		newPrimaryKeys := association.getPrimaryKeys(field.Interface())
+
+		var addedPrimaryKeys = []interface{}{}
+		for _, new := range newPrimaryKeys {
+			hasEqual := false
+			for _, old := range oldPrimaryKeys {
+				if reflect.DeepEqual(new, old) {
+					hasEqual = true
+					break
+				}
+			}
+			if !hasEqual {
+				addedPrimaryKeys = append(addedPrimaryKeys, new)
+			}
+		}
+		for _, primaryKey := range association.getPrimaryKeys(values...) {
+			addedPrimaryKeys = append(addedPrimaryKeys, primaryKey)
+		}
+
+		whereSql := fmt.Sprintf("%v.%v NOT IN (?)", relationship.joinTable, scope.Quote(ToSnake(relationship.associationForeignKey)))
+		scope.db.Model("").Table(relationship.joinTable).Where(whereSql, addedPrimaryKeys).Delete("")
+	} else {
+		association.err(errors.New("replace only support many to many"))
+	}
 	return association
 }
 
@@ -122,17 +159,17 @@ func (association *Association) Count() int {
 			relationship.joinTable,
 			relationship.joinTable,
 			scope.Quote(ToSnake(relationship.foreignKey)))
-		scope.db.Table(newScope.QuotedTableName()).Where(whereSql, association.PrimaryKey).NewScope("").count(&count)
+		scope.db.Model("").Table(newScope.QuotedTableName()).Where(whereSql, association.PrimaryKey).Count(&count)
 	} else if relationship.kind == "has_many" {
 		whereSql := fmt.Sprintf("%v.%v = ?", newScope.QuotedTableName(), newScope.Quote(ToSnake(relationship.foreignKey)))
-		scope.db.Table(newScope.QuotedTableName()).Where(whereSql, association.PrimaryKey).NewScope("").count(&count)
+		scope.db.Model("").Table(newScope.QuotedTableName()).Where(whereSql, association.PrimaryKey).Count(&count)
 	} else if relationship.kind == "has_one" {
 		whereSql := fmt.Sprintf("%v.%v = ?", newScope.QuotedTableName(), relationship.foreignKey)
-		scope.db.Table(newScope.QuotedTableName()).Where(whereSql, association.PrimaryKey).NewScope("").count(&count)
+		scope.db.Model("").Table(newScope.QuotedTableName()).Where(whereSql, association.PrimaryKey).Count(&count)
 	} else if relationship.kind == "belongs_to" {
 		if v, ok := scope.FieldByName(association.Column); ok {
 			whereSql := fmt.Sprintf("%v.%v = ?", newScope.QuotedTableName(), relationship.foreignKey)
-			scope.db.Table(newScope.QuotedTableName()).Where(whereSql, v).NewScope("").count(&count)
+			scope.db.Model("").Table(newScope.QuotedTableName()).Where(whereSql, v).Count(&count)
 		}
 	}
 

association_test.go

@@ -187,6 +187,19 @@ func TestManyToMany(t *testing.T) {
 		t.Errorf("Relations should be deleted with Delete")
 	}
 
+	// Replace
+	var languageB Language
+	db.Where("name = ?", "BB").First(&languageB)
+	db.Debug().Model(&user).Association("Languages").Replace(languageB)
+	if db.Model(&user).Association("Languages").Count() != 1 {
+		t.Errorf("Relations should be deleted with Delete")
+	}
+
+	db.Model(&user).Association("Languages").Replace(&[]Language{{Name: "FF"}, {Name: "JJ"}})
+	if db.Model(&user).Association("Languages").Count() != len([]string{"FF", "JJ"}) {
+		t.Errorf("Relations should be deleted with Delete")
+	}
+
 	// db.Model(&User{}).Many2Many("Languages").Replace(&[]Language{})
 	// db.Model(&User{}).Related(&[]Language{}, "Languages")
 	// SELECT `languages`.* FROM `languages` INNER JOIN `user_languages` ON `languages`.`id` = `user_languages`.`language_id` WHERE `user_languages`.`user_id` = 111