Merge pull request #804 from RichardKnop/feature/reflect-fieldbyname-panic-fix

Fixed an issue with reflect.Value.FieldByName causing panic

preload.go

@@ -186,6 +186,9 @@ func (scope *Scope) handleBelongsToPreload(field *Field, conditions []interface{
 			objects := scope.IndirectValue()
 			for j := 0; j < objects.Len(); j++ {
 				object := reflect.Indirect(objects.Index(j))
+				if object.Kind() == reflect.Ptr {
+					object = reflect.Indirect(objects.Index(j).Elem())
+				}
 				if equalAsString(getRealValue(object, relation.ForeignFieldNames), value) {
 					object.FieldByName(field.Name).Set(result)
 				}
@@ -312,7 +315,11 @@ func (scope *Scope) getColumnAsArray(columns []string) (results [][]interface{})
 		for i := 0; i < values.Len(); i++ {
 			var result []interface{}
 			for _, column := range columns {
-				result = append(result, reflect.Indirect(values.Index(i)).FieldByName(column).Interface())
+				value := reflect.Indirect(values.Index(i))
+				if value.Kind() == reflect.Ptr {
+					value = reflect.Indirect(values.Index(i).Elem())
+				}
+				result = append(result, value.FieldByName(column).Interface())
 			}
 			results = append(results, result)
 		}

preload_test.go

@@ -611,6 +611,70 @@ func TestNestedPreload9(t *testing.T) {
 	}
 }
 
+type Level1A struct {
+	ID    uint
+	Value string
+}
+
+type Level1B struct {
+	ID      uint
+	Value   string
+	Level2s []*Level2
+}
+
+type Level2 struct {
+	ID        uint
+	Value     string
+	Level1AID sql.NullInt64
+	Level1A   *Level1A
+	Level1BID sql.NullInt64
+	Level1B   *Level1B
+}
+
+func TestNestedPreload10(t *testing.T) {
+	DB.DropTableIfExists(&Level2{})
+	DB.DropTableIfExists(&Level1B{})
+	DB.DropTableIfExists(&Level1A{})
+
+	if err := DB.AutoMigrate(&Level1A{}, &Level1B{}, &Level2{}).Error; err != nil {
+		t.Error(err)
+	}
+
+	level1A := &Level1A{Value: "foo"}
+	if err := DB.Save(&level1A).Error; err != nil {
+		t.Error(err)
+	}
+
+	want := []*Level1B{
+		&Level1B{
+			Value: "bar",
+			Level2s: []*Level2{
+				&Level2{
+					Value:   "qux",
+					Level1A: level1A,
+				},
+			},
+		},
+		&Level1B{
+			Value: "bar 2",
+		},
+	}
+	for _, level1B := range want {
+		if err := DB.Save(level1B).Error; err != nil {
+			t.Error(err)
+		}
+	}
+
+	var got []*Level1B
+	if err := DB.Preload("Level2s.Level1A").Find(&got).Error; err != nil {
+		t.Error(err)
+	}
+
+	if !reflect.DeepEqual(got, want) {
+		t.Errorf("got %s; want %s", toJSONString(got), toJSONString(want))
+	}
+}
+
 func TestManyToManyPreloadWithMultiPrimaryKeys(t *testing.T) {
 	if dialect := os.Getenv("GORM_DIALECT"); dialect == "" || dialect == "sqlite" {
 		return