Merge pull request #37 from mdales/mwd-error-on-unknown-migration

Fail migration with error if DB contains unknown migrations.

gormigrate.go

@@ -31,6 +31,9 @@ type Options struct {
 	// UseTransaction makes Gormigrate execute migrations inside a single transaction.
 	// Keep in mind that not all databases support DDL commands inside transactions.
 	UseTransaction bool
+	// ValidateUnknownMigrations will cause migrate to fail if there's unknown migration
+	// IDs in the database
+	ValidateUnknownMigrations bool
 }
 
 // Migration represents a database migration (a modification to be made on the database).
@@ -73,10 +76,11 @@ func (e *DuplicatedIDError) Error() string {
 var (
 	// DefaultOptions can be used if you don't want to think about options.
 	DefaultOptions = &Options{
-		TableName:      "migrations",
-		IDColumnName:   "id",
-		IDColumnSize:   255,
-		UseTransaction: false,
+		TableName:                 "migrations",
+		IDColumnName:              "id",
+		IDColumnSize:              255,
+		UseTransaction:            false,
+		ValidateUnknownMigrations: false,
 	}
 
 	// ErrRollbackImpossible is returned when trying to rollback a migration
@@ -96,6 +100,9 @@ var (
 	// ErrMigrationIDDoesNotExist is returned when migrating or rolling back to a migration ID that
 	// does not exist in the list of migrations
 	ErrMigrationIDDoesNotExist = errors.New("gormigrate: Tried to migrate to an ID that doesn't exist")
+
+	// ErrUnknownPastMigration is returned if a migration exists in the DB that doesn't exist in the code
+	ErrUnknownPastMigration = errors.New("gormigrate: Found migration in DB that does not exist in code")
 )
 
 // New returns a new Gormigrate.
@@ -164,6 +171,16 @@ func (g *Gormigrate) migrate(migrationID string) error {
 		return err
 	}
 
+	if g.options.ValidateUnknownMigrations {
+		unknownMigrations, err := g.unknownMigrationsHaveHappened()
+		if err != nil {
+			return err
+		}
+		if unknownMigrations {
+			return ErrUnknownPastMigration
+		}
+	}
+
 	if g.initSchema != nil {
 		canInitializeSchema, err := g.canInitializeSchema()
 		if err != nil {
@@ -394,6 +411,33 @@ func (g *Gormigrate) canInitializeSchema() (bool, error) {
 	return count == 0, err
 }
 
+func (g *Gormigrate) unknownMigrationsHaveHappened() (bool, error) {
+	sql := fmt.Sprintf("SELECT %s FROM %s", g.options.IDColumnName, g.options.TableName)
+	rows, err := g.tx.Raw(sql).Rows()
+	if err != nil {
+		return false, err
+	}
+	defer rows.Close()
+
+	validIDSet := make(map[string]struct{}, len(g.migrations)+1)
+	validIDSet[initSchemaMigrationID] = struct{}{}
+	for _, migration := range g.migrations {
+		validIDSet[migration.ID] = struct{}{}
+	}
+
+	for rows.Next() {
+		var pastMigrationID string
+		if err := rows.Scan(&pastMigrationID); err != nil {
+			return false, err
+		}
+		if _, ok := validIDSet[pastMigrationID]; !ok {
+			return true, nil
+		}
+	}
+
+	return false, nil
+}
+
 func (g *Gormigrate) insertMigration(id string) error {
 	sql := fmt.Sprintf("INSERT INTO %s (%s) VALUES (?)", g.options.TableName, g.options.IDColumnName)
 	return g.tx.Exec(sql, id).Error

gormigrate_test.go

@@ -366,6 +366,38 @@ func TestMigration_WithUseTransactionsShouldRollback(t *testing.T) {
 	}, "postgres", "sqlite3", "mssql")
 }
 
+func TestUnexpectedMigrationEnabled(t *testing.T) {
+	forEachDatabase(t, func(db *gorm.DB) {
+		options := DefaultOptions
+		options.ValidateUnknownMigrations = true
+		m := New(db, options, migrations)
+
+		// Migrate without initialisation
+		assert.NoError(t, m.Migrate())
+
+		// Try with fewer migrations. Should fail as we see a migration in the db that
+		// we don't recognise any more
+		n := New(db, DefaultOptions, migrations[:1])
+		assert.Equal(t, ErrUnknownPastMigration, n.Migrate())
+	})
+}
+
+func TestUnexpectedMigrationDisabled(t *testing.T) {
+	forEachDatabase(t, func(db *gorm.DB) {
+		options := DefaultOptions
+		options.ValidateUnknownMigrations = false
+		m := New(db, options, migrations)
+
+		// Migrate without initialisation
+		assert.NoError(t, m.Migrate())
+
+		// Try with fewer migrations. Should pass as we see a migration in the db that
+		// we don't recognise any more, but the validation defaults off
+		n := New(db, DefaultOptions, migrations[:1])
+		assert.NoError(t, n.Migrate())
+	})
+}
+
 func tableCount(t *testing.T, db *gorm.DB, tableName string) (count int) {
 	assert.NoError(t, db.Table(tableName).Count(&count).Error)
 	return