From eb480cc08526de02e7b18b504410805ffecd2421 Mon Sep 17 00:00:00 2001
From: Jinzhu <wosmvp@gmail.com>
Date: Tue, 24 Feb 2015 18:48:48 +0800
Subject: [PATCH] Modify struct when update association

---
 association.go      | 28 +++++++++++++++++++++++++---
 association_test.go | 19 +++++++++++++------
 2 files changed, 38 insertions(+), 9 deletions(-)

diff --git a/association.go b/association.go
index c8518946..78e09108 100644
--- a/association.go
+++ b/association.go
@@ -78,8 +78,25 @@ func (association *Association) Delete(values ...interface{}) *Association {
 				relationship.JoinTable, association.Scope.Quote(relationship.ForeignDBName),
 				relationship.JoinTable, association.Scope.Quote(relationship.AssociationForeignDBName))
 
-			association.Scope.db.Model("").Table(relationship.JoinTable).
-				Where(whereSql, association.PrimaryKey, primaryKeys).Delete("")
+			if err := association.Scope.db.Model("").Table(relationship.JoinTable).
+				Where(whereSql, association.PrimaryKey, primaryKeys).Delete("").Error; err == nil {
+				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 {
+						var included = false
+						for _, primaryKey := range primaryKeys {
+							if equalAsString(primaryKey, primaryField.Field.Interface()) {
+								included = true
+							}
+						}
+						if !included {
+							leftValues = reflect.Append(leftValues, value)
+						}
+					}
+				}
+				association.Field.Set(leftValues)
+			}
 		} else {
 			association.setErr(errors.New("delete only support many to many"))
 		}
@@ -94,6 +111,7 @@ func (association *Association) Replace(values ...interface{}) *Association {
 		field := association.Field.Field
 
 		oldPrimaryKeys := association.getPrimaryKeys(field.Interface())
+		association.Field.Set(reflect.Zero(association.Field.Field.Type()))
 		association.Append(values...)
 		newPrimaryKeys := association.getPrimaryKeys(field.Interface())
 
@@ -130,7 +148,11 @@ func (association *Association) Clear() *Association {
 	scope := association.Scope
 	if relationship.Kind == "many_to_many" {
 		whereSql := fmt.Sprintf("%v.%v = ?", relationship.JoinTable, scope.Quote(relationship.ForeignDBName))
-		scope.db.Model("").Table(relationship.JoinTable).Where(whereSql, association.PrimaryKey).Delete("")
+		if err := scope.db.Model("").Table(relationship.JoinTable).Where(whereSql, association.PrimaryKey).Delete("").Error; err == nil {
+			association.Field.Set(reflect.Zero(association.Field.Field.Type()))
+		} else {
+			association.setErr(err)
+		}
 	} else {
 		association.setErr(errors.New("clear only support many to many"))
 	}
diff --git a/association_test.go b/association_test.go
index 201eed53..fb73d443 100644
--- a/association_test.go
+++ b/association_test.go
@@ -1,6 +1,9 @@
 package gorm_test
 
-import "testing"
+import (
+	"os"
+	"testing"
+)
 
 func TestHasOneAndHasManyAssociation(t *testing.T) {
 	DB.DropTable(Category{})
@@ -172,11 +175,15 @@ func TestManyToMany(t *testing.T) {
 	}
 
 	// Delete
+	user.Languages = []Language{}
+	DB.Model(&user).Association("Languages").Find(&user.Languages)
+
 	var language Language
 	DB.Where("name = ?", "EE").First(&language)
 	DB.Model(&user).Association("Languages").Delete(language, &language)
-	if DB.Model(&user).Association("Languages").Count() != len(totalLanguages)-1 {
+	if DB.Model(&user).Association("Languages").Count() != len(totalLanguages)-1 || len(user.Languages) != len(totalLanguages)-1 {
 		t.Errorf("Relations should be deleted with Delete")
+		os.Exit(1)
 	}
 	if DB.Where("name = ?", "EE").First(&Language{}).RecordNotFound() {
 		t.Errorf("Language EE should not be deleted")
@@ -189,7 +196,7 @@ func TestManyToMany(t *testing.T) {
 	DB.Save(&user2)
 
 	DB.Model(&user).Association("Languages").Delete(languages, &languages)
-	if DB.Model(&user).Association("Languages").Count() != len(totalLanguages)-3 {
+	if DB.Model(&user).Association("Languages").Count() != len(totalLanguages)-3 || len(user.Languages) != len(totalLanguages)-3 {
 		t.Errorf("Relations should be deleted with Delete")
 	}
 
@@ -201,18 +208,18 @@ func TestManyToMany(t *testing.T) {
 	var languageB Language
 	DB.Where("name = ?", "BB").First(&languageB)
 	DB.Model(&user).Association("Languages").Replace(languageB)
-	if DB.Model(&user).Association("Languages").Count() != 1 {
+	if len(user.Languages) != 1 || DB.Model(&user).Association("Languages").Count() != 1 {
 		t.Errorf("Relations should be replaced")
 	}
 
 	DB.Model(&user).Association("Languages").Replace(&[]Language{{Name: "FF"}, {Name: "JJ"}})
-	if DB.Model(&user).Association("Languages").Count() != len([]string{"FF", "JJ"}) {
+	if len(user.Languages) != 2 || DB.Model(&user).Association("Languages").Count() != len([]string{"FF", "JJ"}) {
 		t.Errorf("Relations should be replaced")
 	}
 
 	// Clear
 	DB.Model(&user).Association("Languages").Clear()
-	if DB.Model(&user).Association("Languages").Count() != 0 {
+	if len(user.Languages) != 0 || DB.Model(&user).Association("Languages").Count() != 0 {
 		t.Errorf("Relations should be cleared")
 	}
 }