From e8cc338a653629f494595bbd16a35ba9d0c26e19 Mon Sep 17 00:00:00 2001
From: Jeffrey Walter <jeffreydwalter@gmail.com>
Date: Sat, 27 Apr 2024 16:57:02 -0500
Subject: [PATCH] fix: fix issue with has-many join and pointer fields (#950)

---
 internal/dbtest/db_test.go | 112 ++++++++++++++++++++++++++++++++++++-
 model_table_has_many.go    |  22 +++++++-
 2 files changed, 131 insertions(+), 3 deletions(-)

diff --git a/internal/dbtest/db_test.go b/internal/dbtest/db_test.go
index 43fee3601..469bb9eeb 100644
--- a/internal/dbtest/db_test.go
+++ b/internal/dbtest/db_test.go
@@ -44,7 +44,7 @@ const (
 )
 
 var allDBs = map[string]func(tb testing.TB) *bun.DB{
-	pgName:        pg,
+	pgName: pg,
 	pgxName:       pgx,
 	mysql5Name:    mysql5,
 	mysql8Name:    mysql8,
@@ -258,6 +258,8 @@ func TestDB(t *testing.T) {
 		{testFKViolation},
 		{testWithForeignKeysAndRules},
 		{testWithForeignKeys},
+		{testWithForeignKeysHasMany},
+		{testWithPointerForeignKeysHasMany},
 		{testInterfaceAny},
 		{testInterfaceJSON},
 		{testScanRawMessage},
@@ -1043,6 +1045,114 @@ func testWithForeignKeys(t *testing.T, db *bun.DB) {
 	require.Equal(t, d.User.Name, "root")
 }
 
+func testWithForeignKeysHasMany(t *testing.T, db *bun.DB) {
+	type User struct {
+		ID     int `bun:",pk"`
+		DeckID int
+		Name   string
+	}
+	type Deck struct {
+		ID    int     `bun:",pk"`
+		Users []*User `bun:"rel:has-many,join:id=deck_id"`
+	}
+
+	if db.Dialect().Name() == dialect.SQLite {
+		_, err := db.Exec("PRAGMA foreign_keys = ON;")
+		require.NoError(t, err)
+	}
+
+	for _, model := range []interface{}{(*Deck)(nil), (*User)(nil)} {
+		_, err := db.NewDropTable().Model(model).IfExists().Exec(ctx)
+		require.NoError(t, err)
+	}
+
+	mustResetModel(t, ctx, db, (*User)(nil))
+	_, err := db.NewCreateTable().
+		Model((*Deck)(nil)).
+		IfNotExists().
+		WithForeignKeys().
+		Exec(ctx)
+	require.NoError(t, err)
+	mustDropTableOnCleanup(t, ctx, db, (*Deck)(nil))
+
+	deckID := 1
+	deck := Deck{ID: deckID}
+	_, err = db.NewInsert().Model(&deck).Exec(ctx)
+	require.NoError(t, err)
+
+	userID1 := 1
+	userID2 := 2
+	users := []*User{
+		{ID: userID1, DeckID: deckID, Name: "user 1"},
+		{ID: userID2, DeckID: deckID, Name: "user 2"},
+	}
+
+	res, err := db.NewInsert().Model(&users).Exec(ctx)
+	require.NoError(t, err)
+
+	affected, err := res.RowsAffected()
+	require.NoError(t, err)
+	require.Equal(t, int64(2), affected)
+
+	err = db.NewSelect().Model(&deck).Relation("Users").Scan(ctx)
+	require.NoError(t, err)
+	require.Len(t, deck.Users, 2)
+}
+
+func testWithPointerForeignKeysHasMany(t *testing.T, db *bun.DB) {
+	type User struct {
+		ID     *int `bun:",pk"`
+		DeckID *int
+		Name   string
+	}
+	type Deck struct {
+		ID    *int    `bun:",pk"`
+		Users []*User `bun:"rel:has-many,join:id=deck_id"`
+	}
+
+	if db.Dialect().Name() == dialect.SQLite {
+		_, err := db.Exec("PRAGMA foreign_keys = ON;")
+		require.NoError(t, err)
+	}
+
+	for _, model := range []interface{}{(*Deck)(nil), (*User)(nil)} {
+		_, err := db.NewDropTable().Model(model).IfExists().Exec(ctx)
+		require.NoError(t, err)
+	}
+
+	mustResetModel(t, ctx, db, (*User)(nil))
+	_, err := db.NewCreateTable().
+		Model((*Deck)(nil)).
+		IfNotExists().
+		WithForeignKeys().
+		Exec(ctx)
+	require.NoError(t, err)
+	mustDropTableOnCleanup(t, ctx, db, (*Deck)(nil))
+
+	deckID := 1
+	deck := Deck{ID: &deckID}
+	_, err = db.NewInsert().Model(&deck).Exec(ctx)
+	require.NoError(t, err)
+
+	userID1 := 1
+	userID2 := 2
+	users := []*User{
+		{ID: &userID1, DeckID: &deckID, Name: "user 1"},
+		{ID: &userID2, DeckID: &deckID, Name: "user 2"},
+	}
+
+	res, err := db.NewInsert().Model(&users).Exec(ctx)
+	require.NoError(t, err)
+
+	affected, err := res.RowsAffected()
+	require.NoError(t, err)
+	require.Equal(t, int64(2), affected)
+
+	err = db.NewSelect().Model(&deck).Relation("Users").Scan(ctx)
+	require.NoError(t, err)
+	require.Len(t, deck.Users, 2)
+}
+
 func testInterfaceAny(t *testing.T, db *bun.DB) {
 	switch db.Dialect().Name() {
 	case dialect.MySQL:
diff --git a/model_table_has_many.go b/model_table_has_many.go
index 3d8a5da6f..f3e977fca 100644
--- a/model_table_has_many.go
+++ b/model_table_has_many.go
@@ -94,7 +94,7 @@ func (m *hasManyModel) Scan(src interface{}) error {
 
 	for _, f := range m.rel.JoinFields {
 		if f.Name == field.Name {
-			m.structKey = append(m.structKey, field.Value(m.strct).Interface())
+			m.structKey = append(m.structKey, getFieldValue(field.Value(m.strct)))
 			break
 		}
 	}
@@ -103,6 +103,7 @@ func (m *hasManyModel) Scan(src interface{}) error {
 }
 
 func (m *hasManyModel) parkStruct() error {
+
 	baseValues, ok := m.baseValues[internal.NewMapKey(m.structKey)]
 	if !ok {
 		return fmt.Errorf(
@@ -143,7 +144,24 @@ func baseValues(model TableModel, fields []*schema.Field) map[internal.MapKey][]
 
 func modelKey(key []interface{}, strct reflect.Value, fields []*schema.Field) []interface{} {
 	for _, f := range fields {
-		key = append(key, f.Value(strct).Interface())
+		key = append(key, getFieldValue(f.Value(strct)))
 	}
 	return key
 }
+
+// getFieldValue extracts the value from a reflect.Value, handling pointer types appropriately.
+func getFieldValue(fieldValue reflect.Value) interface{} {
+	var keyValue interface{}
+
+	if fieldValue.Kind() == reflect.Ptr {
+		if !fieldValue.IsNil() {
+			keyValue = fieldValue.Elem().Interface()
+		} else {
+			keyValue = nil
+		}
+	} else {
+		keyValue = fieldValue.Interface()
+	}
+
+	return keyValue
+}