fix: stmt.Changed zero value filed behavior (#5281)

* fix: stmt.Changed zero value filed behavior

* chore: rename var

statement.go

@@ -609,10 +609,10 @@ func (stmt *Statement) Changed(fields ...string) bool {
 	changed := func(field *schema.Field) bool {
 		fieldValue, _ := field.ValueOf(stmt.Context, modelValue)
 		if v, ok := selectColumns[field.DBName]; (ok && v) || (!ok && !restricted) {
-			if v, ok := stmt.Dest.(map[string]interface{}); ok {
-				if fv, ok := v[field.Name]; ok {
+			if mv, mok := stmt.Dest.(map[string]interface{}); mok {
+				if fv, ok := mv[field.Name]; ok {
 					return !utils.AssertEqual(fv, fieldValue)
-				} else if fv, ok := v[field.DBName]; ok {
+				} else if fv, ok := mv[field.DBName]; ok {
 					return !utils.AssertEqual(fv, fieldValue)
 				}
 			} else {
@@ -622,6 +622,9 @@ func (stmt *Statement) Changed(fields ...string) bool {
 				}
 
 				changedValue, zero := field.ValueOf(stmt.Context, destValue)
+				if v {
+					return !utils.AssertEqual(changedValue, fieldValue)
+				}
 				return !zero && !utils.AssertEqual(changedValue, fieldValue)
 			}
 		}

tests/hooks_test.go

@@ -375,13 +375,19 @@ func TestSetColumn(t *testing.T) {
 		t.Errorf("invalid data after update, got %+v", product)
 	}
 
+	// Code changed, price should changed
+	DB.Model(&product).Select("Name", "Code", "Price").Updates(Product3{Name: "Product New4", Code: ""})
+	if product.Name != "Product New4" || product.Price != 320 || product.Code != "" {
+		t.Errorf("invalid data after update, got %+v", product)
+	}
+
 	DB.Model(&product).UpdateColumns(Product3{Code: "L1215"})
-	if product.Price != 270 || product.Code != "L1215" {
+	if product.Price != 320 || product.Code != "L1215" {
 		t.Errorf("invalid data after update, got %+v", product)
 	}
 
 	DB.Model(&product).Session(&gorm.Session{SkipHooks: true}).Updates(Product3{Code: "L1216"})
-	if product.Price != 270 || product.Code != "L1216" {
+	if product.Price != 320 || product.Code != "L1216" {
 		t.Errorf("invalid data after update, got %+v", product)
 	}