gormschema: support customize JoinTable (#40)

* feat: support Customize JoinTable

* fix: re-order sql statements output of test cases

* chore: update README for Customize JoinTable usage

* fix: use callback instead of struct for params

* fix: allow WithJoinTable as an option

* fix: set up proper test case for customize table

* chore: update README for Customize JoinTable usage

* refactor: sort relationships map to have a deterministic SQL output

* chore: use slices.Sort instead of sort.Strings

README.md

@@ -184,9 +184,8 @@ The provider supports the following databases:
 
 * **Foreign key constraints not generated correctly** -
   If a [Customize JoinTable](https://gorm.io/docs/many_to_many.html#Customize-JoinTable) is defined in the schema, 
-  you need to use the provider as a [Go Program](#as-go-file) and pass to the `Load` method the tables in their dependency order. i.e.,
-  Join tables after their parent tables.  
-
+  you need to use the provider as a [Go Program](#as-go-file) and set it up using the `WithJoinTable` option.
+
   for example if those are your models:
   ```go
   type Person struct {
@@ -210,7 +209,11 @@ The provider supports the following databases:
 
   you should use the following code:
   ```go
-  stmts, err := gormschema.New("mysql").Load(&models.Person{}, &models.Address{}, &models.PersonAddress{})
+  stmts, err := gormschema.New("mysql",
+  	gormschema.WithJoinTable(
+  		&Models.Person{}, "Addresses", &Models.PersonAddress{},
+  	),
+  ).Load(&Models.Address{}, &Models.Person{})
   ```
 
 ### License

gormschema/gorm.go

@@ -28,8 +28,9 @@ func New(dialect string, opts ...Option) *Loader {
 type (
 	// Loader is a Loader for gorm schema.
 	Loader struct {
-		dialect string
-		config  *gorm.Config
+		dialect           string
+		config            *gorm.Config
+		beforeAutoMigrate []func(*gorm.DB) error
 	}
 	// Option configures the Loader.
 	Option func(*Loader)
@@ -85,6 +86,11 @@ func (l *Loader) Load(models ...any) (string, error) {
 	if l.dialect != "sqlite" {
 		db.Config.DisableForeignKeyConstraintWhenMigrating = true
 	}
+	for _, cb := range l.beforeAutoMigrate {
+		if err = cb(db); err != nil {
+			return "", err
+		}
+	}
 	if err = db.AutoMigrate(models...); err != nil {
 		return "", err
 	}
@@ -140,11 +146,20 @@ func (m *migrator) HasTable(dst any) bool {
 
 // CreateConstraints detects constraints on the given model and creates them using `m.dialectMigrator`.
 func (m *migrator) CreateConstraints(models []any) error {
-	// Reverse the order of models to ensure many 2 many tables constraints are created first, assuming they are at the end.
-	slices.Reverse(models)
 	for _, model := range m.ReorderModels(models, true) {
 		err := m.Migrator.RunWithValue(model, func(stmt *gorm.Statement) error {
-			for _, rel := range stmt.Schema.Relationships.Relations {
+
+			relationNames := make([]string, 0, len(stmt.Schema.Relationships.Relations))
+			for name := range stmt.Schema.Relationships.Relations {
+				relationNames = append(relationNames, name)
+			}
+			// since Relations is a map, the order of the keys is not guaranteed
+			// so we sort the keys to make the sql output deterministic
+			slices.Sort(relationNames)
+
+			for _, name := range relationNames {
+				rel := stmt.Schema.Relationships.Relations[name]
+
 				if rel.Field.IgnoreMigration {
 					continue
 				}
@@ -163,3 +178,12 @@ func (m *migrator) CreateConstraints(models []any) error {
 	}
 	return nil
 }
+
+// WithJoinTable sets up a join table for the given model and field.
+func WithJoinTable(model any, field string, jointable any) Option {
+	return func(l *Loader) {
+		l.beforeAutoMigrate = append(l.beforeAutoMigrate, func(db *gorm.DB) error {
+			return db.SetupJoinTable(model, field, jointable)
+		})
+	}
+}

gormschema/gorm_test.go

@@ -60,8 +60,8 @@ func TestMySQLConfig(t *testing.T) {
 	require.NoError(t, err)
 	requireEqualContent(t, sql, "testdata/mysql_no_fk")
 	resetSession()
-	l = New("mysql")
-	sql, err = l.Load(customjointable.Address{}, customjointable.Person{}, customjointable.PersonAddress{})
+	l = New("mysql", WithJoinTable(&customjointable.Person{}, "Addresses", &customjointable.PersonAddress{}))
+	sql, err = l.Load(customjointable.Address{}, customjointable.Person{})
 	require.NoError(t, err)
 	requireEqualContent(t, sql, "testdata/mysql_custom_join_table")
 }

gormschema/testdata/mysql_custom_join_table

@@ -1,5 +1,5 @@
 CREATE TABLE `addresses` (`id` bigint AUTO_INCREMENT,`name` longtext,PRIMARY KEY (`id`));
 CREATE TABLE `people` (`id` bigint AUTO_INCREMENT,`name` longtext,PRIMARY KEY (`id`));
 CREATE TABLE `person_addresses` (`person_id` bigint,`address_id` bigint,`created_at` datetime(3) NULL,`deleted_at` datetime(3) NULL,PRIMARY KEY (`person_id`,`address_id`));
-ALTER TABLE `person_addresses` ADD CONSTRAINT `fk_person_addresses_person` FOREIGN KEY (`person_id`) REFERENCES `people`(`id`);
 ALTER TABLE `person_addresses` ADD CONSTRAINT `fk_person_addresses_address` FOREIGN KEY (`address_id`) REFERENCES `addresses`(`id`);
+ALTER TABLE `person_addresses` ADD CONSTRAINT `fk_person_addresses_person` FOREIGN KEY (`person_id`) REFERENCES `people`(`id`);

gormschema/testdata/mysql_default

@@ -2,6 +2,6 @@ CREATE TABLE `events` (`eventId` varchar(191),`locationId` varchar(191),PRIMARY
 CREATE TABLE `locations` (`locationId` varchar(191),`eventId` varchar(191),PRIMARY KEY (`locationId`),UNIQUE INDEX `idx_locations_event_id` (`eventId`));
 CREATE TABLE `users` (`id` bigint unsigned AUTO_INCREMENT,`created_at` datetime(3) NULL,`updated_at` datetime(3) NULL,`deleted_at` datetime(3) NULL,`name` longtext,PRIMARY KEY (`id`),INDEX `idx_users_deleted_at` (`deleted_at`));
 CREATE TABLE `pets` (`id` bigint unsigned AUTO_INCREMENT,`created_at` datetime(3) NULL,`updated_at` datetime(3) NULL,`deleted_at` datetime(3) NULL,`name` longtext,`user_id` bigint unsigned,PRIMARY KEY (`id`),INDEX `idx_pets_deleted_at` (`deleted_at`));
-ALTER TABLE `pets` ADD CONSTRAINT `fk_users_pets` FOREIGN KEY (`user_id`) REFERENCES `users`(`id`);
-ALTER TABLE `locations` ADD CONSTRAINT `fk_events_location` FOREIGN KEY (`eventId`) REFERENCES `events`(`eventId`);
 ALTER TABLE `events` ADD CONSTRAINT `fk_locations_event` FOREIGN KEY (`locationId`) REFERENCES `locations`(`locationId`);
+ALTER TABLE `locations` ADD CONSTRAINT `fk_events_location` FOREIGN KEY (`eventId`) REFERENCES `events`(`eventId`);
+ALTER TABLE `pets` ADD CONSTRAINT `fk_users_pets` FOREIGN KEY (`user_id`) REFERENCES `users`(`id`);

gormschema/testdata/postgresql_default

@@ -6,6 +6,6 @@ CREATE TABLE "users" ("id" bigserial,"created_at" timestamptz,"updated_at" times
 CREATE INDEX IF NOT EXISTS "idx_users_deleted_at" ON "users" ("deleted_at");
 CREATE TABLE "pets" ("id" bigserial,"created_at" timestamptz,"updated_at" timestamptz,"deleted_at" timestamptz,"name" text,"user_id" bigint,PRIMARY KEY ("id"));
 CREATE INDEX IF NOT EXISTS "idx_pets_deleted_at" ON "pets" ("deleted_at");
-ALTER TABLE "pets" ADD CONSTRAINT "fk_users_pets" FOREIGN KEY ("user_id") REFERENCES "users"("id");
-ALTER TABLE "locations" ADD CONSTRAINT "fk_events_location" FOREIGN KEY ("eventId") REFERENCES "events"("eventId");
 ALTER TABLE "events" ADD CONSTRAINT "fk_locations_event" FOREIGN KEY ("locationId") REFERENCES "locations"("locationId");
+ALTER TABLE "locations" ADD CONSTRAINT "fk_events_location" FOREIGN KEY ("eventId") REFERENCES "events"("eventId");
+ALTER TABLE "pets" ADD CONSTRAINT "fk_users_pets" FOREIGN KEY ("user_id") REFERENCES "users"("id");

gormschema/testdata/sqlserver_default

@@ -6,6 +6,6 @@ CREATE TABLE "users" ("id" bigint IDENTITY(1,1),"created_at" datetimeoffset,"upd
 CREATE INDEX "idx_users_deleted_at" ON "users"("deleted_at");
 CREATE TABLE "pets" ("id" bigint IDENTITY(1,1),"created_at" datetimeoffset,"updated_at" datetimeoffset,"deleted_at" datetimeoffset,"name" nvarchar(MAX),"user_id" bigint,PRIMARY KEY ("id"));
 CREATE INDEX "idx_pets_deleted_at" ON "pets"("deleted_at");
-ALTER TABLE "pets" ADD CONSTRAINT "fk_users_pets" FOREIGN KEY ("user_id") REFERENCES "users"("id");
-ALTER TABLE "locations" ADD CONSTRAINT "fk_events_location" FOREIGN KEY ("eventId") REFERENCES "events"("eventId");
 ALTER TABLE "events" ADD CONSTRAINT "fk_locations_event" FOREIGN KEY ("locationId") REFERENCES "locations"("locationId");
+ALTER TABLE "locations" ADD CONSTRAINT "fk_events_location" FOREIGN KEY ("eventId") REFERENCES "events"("eventId");
+ALTER TABLE "pets" ADD CONSTRAINT "fk_users_pets" FOREIGN KEY ("user_id") REFERENCES "users"("id");