Fix Scan with interface

finisher_api.go

@@ -506,7 +506,12 @@ func (db *DB) ScanRows(rows *sql.Rows, dest interface{}) error {
 	tx.Statement.Dest = dest
 	tx.Statement.ReflectValue = reflect.ValueOf(dest)
 	for tx.Statement.ReflectValue.Kind() == reflect.Ptr {
-		tx.Statement.ReflectValue = tx.Statement.ReflectValue.Elem()
+		elem := tx.Statement.ReflectValue.Elem()
+		if !elem.IsValid() {
+			elem = reflect.New(tx.Statement.ReflectValue.Type().Elem())
+			tx.Statement.ReflectValue.Set(elem)
+		}
+		tx.Statement.ReflectValue = elem
 	}
 	Scan(rows, tx, true)
 	return tx.Error

scan.go

@@ -97,11 +97,15 @@ func Scan(rows *sql.Rows, db *DB, initialized bool) {
 		}
 	default:
 		Schema := db.Statement.Schema
+		reflectValue := db.Statement.ReflectValue
+		if reflectValue.Kind() == reflect.Interface {
+			reflectValue = reflectValue.Elem()
+		}
 
-		switch db.Statement.ReflectValue.Kind() {
+		switch reflectValue.Kind() {
 		case reflect.Slice, reflect.Array:
 			var (
-				reflectValueType = db.Statement.ReflectValue.Type().Elem()
+				reflectValueType = reflectValue.Type().Elem()
 				isPtr            = reflectValueType.Kind() == reflect.Ptr
 				fields           = make([]*schema.Field, len(columns))
 				joinFields       [][2]*schema.Field
@@ -111,7 +115,7 @@ func Scan(rows *sql.Rows, db *DB, initialized bool) {
 				reflectValueType = reflectValueType.Elem()
 			}
 
-			db.Statement.ReflectValue.Set(reflect.MakeSlice(db.Statement.ReflectValue.Type(), 0, 20))
+			db.Statement.ReflectValue.Set(reflect.MakeSlice(reflectValue.Type(), 0, 20))
 
 			if Schema != nil {
 				if reflectValueType != Schema.ModelType && reflectValueType.Kind() == reflect.Struct {
@@ -186,13 +190,13 @@ func Scan(rows *sql.Rows, db *DB, initialized bool) {
 				}
 
 				if isPtr {
-					db.Statement.ReflectValue.Set(reflect.Append(db.Statement.ReflectValue, elem))
+					db.Statement.ReflectValue.Set(reflect.Append(reflectValue, elem))
 				} else {
-					db.Statement.ReflectValue.Set(reflect.Append(db.Statement.ReflectValue, elem.Elem()))
+					db.Statement.ReflectValue.Set(reflect.Append(reflectValue, elem.Elem()))
 				}
 			}
 		case reflect.Struct, reflect.Ptr:
-			if db.Statement.ReflectValue.Type() != Schema.ModelType {
+			if reflectValue.Type() != Schema.ModelType {
 				Schema, _ = schema.Parse(db.Statement.Dest, db.cacheStore, db.NamingStrategy)
 			}
 
@@ -220,11 +224,11 @@ func Scan(rows *sql.Rows, db *DB, initialized bool) {
 
 				for idx, column := range columns {
 					if field := Schema.LookUpField(column); field != nil && field.Readable {
-						field.Set(db.Statement.ReflectValue, values[idx])
+						field.Set(reflectValue, values[idx])
 					} else if names := strings.Split(column, "__"); len(names) > 1 {
 						if rel, ok := Schema.Relationships.Relations[names[0]]; ok {
 							if field := rel.FieldSchema.LookUpField(strings.Join(names[1:], "__")); field != nil && field.Readable {
-								relValue := rel.Field.ReflectValueOf(db.Statement.ReflectValue)
+								relValue := rel.Field.ReflectValueOf(reflectValue)
 								value := reflect.ValueOf(values[idx]).Elem()
 
 								if relValue.Kind() == reflect.Ptr && relValue.IsNil() {

schema/schema.go

@@ -77,7 +77,11 @@ func Parse(dest interface{}, cacheStore *sync.Map, namer Namer) (*Schema, error)
 		return nil, fmt.Errorf("%w: %+v", ErrUnsupportedDataType, dest)
 	}
 
-	modelType := reflect.ValueOf(dest).Type()
+	modelType := reflect.Indirect(reflect.ValueOf(dest)).Type()
+	if modelType.Kind() == reflect.Interface {
+		modelType = reflect.Indirect(reflect.ValueOf(dest)).Elem().Type()
+	}
+
 	for modelType.Kind() == reflect.Slice || modelType.Kind() == reflect.Array || modelType.Kind() == reflect.Ptr {
 		modelType = modelType.Elem()
 	}

tests/scan_test.go

@@ -29,8 +29,9 @@ func TestScan(t *testing.T) {
 	}
 
 	var resPointer *result
-	DB.Table("users").Select("id, name, age").Where("id = ?", user3.ID).Scan(&resPointer)
+	if err := DB.Table("users").Select("id, name, age").Where("id = ?", user3.ID).Scan(&resPointer).Error; err != nil {
-	if res.ID != user3.ID || res.Name != user3.Name || res.Age != int(user3.Age) {
+		t.Fatalf("Failed to query with pointer of value, got error %v", err)
+	} else if resPointer.ID != user3.ID || resPointer.Name != user3.Name || resPointer.Age != int(user3.Age) {
 		t.Fatalf("Scan into struct should work, got %#v, should %#v", res, user3)
 	}
 
@@ -70,6 +71,38 @@ func TestScan(t *testing.T) {
 	if uint(id) != user2.ID {
 		t.Errorf("Failed to scan to customized data type")
 	}
+
+	var resInt interface{}
+	resInt = &User{}
+	if err := DB.Table("users").Select("id, name, age").Where("id = ?", user3.ID).Find(&resInt).Error; err != nil {
+		t.Fatalf("Failed to query with pointer of value, got error %v", err)
+	} else if resInt.(*User).ID != user3.ID || resInt.(*User).Name != user3.Name || resInt.(*User).Age != user3.Age {
+		t.Fatalf("Scan into struct should work, got %#v, should %#v", resInt, user3)
+	}
+
+	var resInt2 interface{}
+	resInt2 = &User{}
+	if err := DB.Table("users").Select("id, name, age").Where("id = ?", user3.ID).Scan(&resInt2).Error; err != nil {
+		t.Fatalf("Failed to query with pointer of value, got error %v", err)
+	} else if resInt2.(*User).ID != user3.ID || resInt2.(*User).Name != user3.Name || resInt2.(*User).Age != user3.Age {
+		t.Fatalf("Scan into struct should work, got %#v, should %#v", resInt2, user3)
+	}
+
+	var resInt3 interface{}
+	resInt3 = []User{}
+	if err := DB.Table("users").Select("id, name, age").Where("id = ?", user3.ID).Find(&resInt3).Error; err != nil {
+		t.Fatalf("Failed to query with pointer of value, got error %v", err)
+	} else if rus := resInt3.([]User); len(rus) == 0 || rus[0].ID != user3.ID || rus[0].Name != user3.Name || rus[0].Age != user3.Age {
+		t.Fatalf("Scan into struct should work, got %#v, should %#v", resInt3, user3)
+	}
+
+	var resInt4 interface{}
+	resInt4 = []User{}
+	if err := DB.Table("users").Select("id, name, age").Where("id = ?", user3.ID).Scan(&resInt4).Error; err != nil {
+		t.Fatalf("Failed to query with pointer of value, got error %v", err)
+	} else if rus := resInt4.([]User); len(rus) == 0 || rus[0].ID != user3.ID || rus[0].Name != user3.Name || rus[0].Age != user3.Age {
+		t.Fatalf("Scan into struct should work, got %#v, should %#v", resInt4, user3)
+	}
 }
 
 func TestScanRows(t *testing.T) {