`UpdateColumns(...)` no longer triggers save of associated records.

README.md

@@ -360,7 +360,7 @@ db.Model(&user).Updates(User{Name: "hello", Age: 18})
 
 ### Update Without Callbacks
 
-By default, update will call BeforeUpdate, AfterUpdate callbacks, if you want to update w/o callbacks:
+By default, update will call BeforeUpdate, AfterUpdate callbacks, if you want to update w/o callbacks and w/o saving associations:
 
 ```go
 db.Model(&user).UpdateColumn("name", "hello")

callback_shared.go

@@ -11,6 +11,9 @@ func CommitOrRollbackTransaction(scope *Scope) {
 }
 
 func SaveBeforeAssociations(scope *Scope) {
+	if !scope.shouldSaveAssociations() {
+		return
+	}
 	for _, field := range scope.Fields() {
 		if scope.changeableField(field) && !field.IsBlank && !field.IsIgnored {
 			if relationship := field.Relationship; relationship != nil && relationship.Kind == "belongs_to" {
@@ -25,6 +28,9 @@ func SaveBeforeAssociations(scope *Scope) {
 }
 
 func SaveAfterAssociations(scope *Scope) {
+	if !scope.shouldSaveAssociations() {
+		return
+	}
 	for _, field := range scope.Fields() {
 		if scope.changeableField(field) && !field.IsBlank && !field.IsIgnored {
 			if relationship := field.Relationship; relationship != nil &&

main.go

@@ -266,6 +266,7 @@ func (s *DB) UpdateColumn(attrs ...interface{}) *DB {
 func (s *DB) UpdateColumns(values interface{}) *DB {
 	return s.clone().NewScope(s.Value).
 		Set("gorm:update_column", true).
+		Set("gorm:save_associations", false).
 		InstanceSet("gorm:update_interface", values).
 		callCallbacks(s.parent.callback.updates).db
 }

scope.go

@@ -398,3 +398,11 @@ func (scope *Scope) changeableField(field *Field) bool {
 
 	return !field.IsIgnored
 }
+
+func (scope *Scope) shouldSaveAssociations() bool {
+	saveAssociations, ok := scope.Get("gorm:save_associations")
+	if ok && !saveAssociations.(bool) {
+		return false
+	}
+	return true
+}

update_test.go

@@ -382,3 +382,32 @@ func TestOmitWithUpdateColumn(t *testing.T) {
 		t.Errorf("Should omit name column when update user")
 	}
 }
+
+func TestUpdateColumnsSkipsAssociations(t *testing.T) {
+	user := getPreparedUser("update_columns_user", "special_role")
+	user.Age = 99
+	address1 := "first street"
+	user.BillingAddress = Address{Address1: address1}
+	DB.Save(user)
+
+	// Update a single field of the user and verify that the changed address is not stored.
+	newAge := int64(100)
+	user.BillingAddress.Address1 = "second street"
+	db := DB.Model(user).UpdateColumns(User{Age: newAge})
+	if db.RowsAffected != 1 {
+		t.Errorf("Expected RowsAffected=1 but instead RowsAffected=%v", DB.RowsAffected)
+	}
+
+	// Verify that Age now=`newAge`.
+	freshUser := &User{Id: user.Id}
+	DB.First(freshUser)
+	if freshUser.Age != newAge {
+		t.Errorf("Expected freshly queried user to have Age=%v but instead found Age=%v", newAge, freshUser.Age)
+	}
+
+	// Verify that user's BillingAddress.Address1 is not changed and is still "first street".
+	DB.First(&freshUser.BillingAddress, freshUser.BillingAddressID)
+	if freshUser.BillingAddress.Address1 != address1 {
+		t.Errorf("Expected user's BillingAddress.Address1=%s to remain unchanged after UpdateColumns invocation, but BillingAddress.Address1=%s", address1, freshUser.BillingAddress.Address1)
+	}
+}