feat: support reset result as nil when record not found

gorm.go

@@ -50,6 +50,8 @@ type Config struct {
 	CreateBatchSize int
 	// TranslateError enabling error translation
 	TranslateError bool
+	// NotFoundAsError set result is nil when no record found and result is ptr
+	NotFoundAsNilWhenPtr bool
 
 	// ClauseBuilders clause builder
 	ClauseBuilders map[string]clause.ClauseBuilder

scan.go

@@ -342,5 +342,9 @@ func Scan(rows Rows, db *DB, mode ScanMode) {
 
 	if db.RowsAffected == 0 && db.Statement.RaiseErrorOnNotFound && db.Error == nil {
 		db.AddError(ErrRecordNotFound)
+		if db.NotFoundAsNilWhenPtr && db.Statement.Dest != nil && reflect.ValueOf(db.Statement.Dest).Kind() == reflect.Ptr {
+			// reset dest to nil
+			reflect.ValueOf(db.Statement.Dest).Elem().Set(reflect.Zero(reflect.ValueOf(db.Statement.Dest).Elem().Type()))
+		}
 	}
 }

tests/query_test.go

@@ -206,6 +206,20 @@ func TestFind(t *testing.T) {
 		}
 	})
 
+	t.Run("NotFoundAsNil", func(t *testing.T) {
+		var first *User
+		if err := DB.Where("name = ?", "find-not-found").First(&first).Error; err != nil {
+			AssertEqual(t, err, gorm.ErrRecordNotFound)
+			AssertEqual(t, first == nil, false)
+		}
+
+		DB.Config.NotFoundAsNilWhenPtr = true
+		if err := DB.Where("name = ?", "find-not-found").First(&first).Error; err != nil {
+			AssertEqual(t, err, gorm.ErrRecordNotFound)
+			AssertEqual(t, first, nil)
+		}
+	})
+
 	var models []User
 	if err := DB.Where("name in (?)", []string{"find"}).Find(&models).Error; err != nil || len(models) != 3 {
 		t.Errorf("errors happened when query find with in clause: %v, length: %v", err, len(models))