Add update tag.

This attempts to address a concern in issues #202 and #192.

It adds a gorm field tag that allows one to specify that the tagged field should always be updated.

callback_shared.go

@@ -16,7 +16,7 @@ func CommitOrRollbackTransaction(scope *Scope) {
 
 func SaveBeforeAssociations(scope *Scope) {
 	for _, field := range scope.Fields() {
-		if !field.IsBlank && !field.IsIgnored {
+		if field.AlwaysUpdate || !field.IsBlank && !field.IsIgnored {
 			relationship := field.Relationship
 			if relationship != nil && relationship.Kind == "belongs_to" {
 				value := field.Field
@@ -42,7 +42,7 @@ func SaveBeforeAssociations(scope *Scope) {
 
 func SaveAfterAssociations(scope *Scope) {
 	for _, field := range scope.Fields() {
-		if !field.IsBlank && !field.IsIgnored {
+		if field.AlwaysUpdate || !field.IsBlank && !field.IsIgnored {
 			relationship := field.Relationship
 			if relationship != nil &&
 				(relationship.Kind == "has_one" || relationship.Kind == "has_many" || relationship.Kind == "many_to_many") {

field.go

@@ -23,6 +23,7 @@ type Field struct {
 	IsBlank      bool
 	IsIgnored    bool
 	IsPrimaryKey bool
+	AlwaysUpdate bool
 }
 
 func (field *Field) IsScanner() bool {

scope.go

@@ -304,7 +304,9 @@ func (scope *Scope) fieldFromStruct(fieldStruct reflect.StructField, withRelatio
 	if fieldStruct.Tag.Get(tagIdentifier) == "-" {
 		field.IsIgnored = true
 	}
-
+	if _, ok := settings["UPDATE"]; ok {
+		field.AlwaysUpdate = true
+	}
 	if !field.IsIgnored {
 		// parse association
 		if !indirectValue.IsValid() {

update_test.go

@@ -158,3 +158,55 @@ func TestUpdateColumn(t *testing.T) {
 		t.Errorf("updatedAt should not be updated with update column")
 	}
 }
+
+func TestAlwaysUpdate(t *testing.T) {
+	type Always struct {
+		Id    int64
+		Name  string
+		Code  string
+		Price int64 `gorm:"update"`
+	}
+
+	DB.DropTable(&Always{})
+	DB.CreateTable(&Always{})
+
+	obj1 := Always{Name: "obj1", Code: "code_1", Price: 10}
+	obj2 := Always{Name: "obj2", Code: "code_2", Price: 20}
+
+	// save initial
+	DB.Save(&obj1).Save(&obj2).UpdateColumn(map[string]interface{}{"code": "columnUpdate2"})
+
+	// fetch and verify
+	var obj3, obj4 Always
+	DB.First(&obj3, obj1.Id)
+	if obj3.Code != "code_1" || obj3.Price != 10 {
+		t.Errorf("obj1 was not saved correctly: expected: %#v got: %#v", obj1, obj3)
+	}
+	DB.First(&obj4, obj2.Id)
+	if obj4.Code != "columnUpdate2" || obj4.Price != 20 {
+		t.Errorf("obj2 was not saved correctly: expected: %#v got: %#v", obj2, obj4)
+	}
+
+	// now update via struct price should change to zero
+	obj5 := Always{Name: "obj2update", Code: "code_2"}
+	DB.Model(obj5).Updates(obj5)
+
+	var obj6 Always
+	DB.First(&obj6, obj2.Id)
+	if obj6.Code != "code_2" || obj6.Name != "obj2update" || obj6.Price != 0 {
+		t.Errorf("obj2 was not saved correctly: got: %#v", obj6)
+	}
+
+	var res []Always
+	DB.Find(&res)
+	if len(res) != 2 {
+		t.Error("Should have 2 objects")
+	}
+
+	// test where clause
+	var res1 []Always
+	DB.Where(Always{}).Find(&res1)
+	if len(res1) != 2 {
+		t.Error("Where() Should have 2 returned objects")
+	}
+}

utils_private.go

@@ -65,7 +65,7 @@ func convertInterfaceToMap(values interface{}) map[string]interface{} {
 		default:
 			scope := Scope{Value: values}
 			for _, field := range scope.Fields() {
-				if !field.IsBlank {
+				if field.AlwaysUpdate || !field.IsBlank {
 					attrs[field.DBName] = field.Field.Interface()
 				}
 			}