Drop table with CASCADE option

dialects/mysql/migrator.go

@@ -24,6 +24,21 @@ func (m Migrator) AlterColumn(value interface{}, field string) error {
 	})
 }
 
+func (m Migrator) DropTable(values ...interface{}) error {
+	values = m.ReorderModels(values, false)
+	tx := m.DB.Session(&gorm.Session{})
+	tx.Exec("SET FOREIGN_KEY_CHECKS = 0;")
+	for i := len(values) - 1; i >= 0; i-- {
+		if err := m.RunWithValue(values[i], func(stmt *gorm.Statement) error {
+			return tx.Exec("DROP TABLE IF EXISTS ? CASCADE", clause.Table{Name: stmt.Table}).Error
+		}); err != nil {
+			return err
+		}
+	}
+	tx.Exec("SET FOREIGN_KEY_CHECKS = 1;")
+	return nil
+}
+
 func (m Migrator) DropConstraint(value interface{}, name string) error {
 	return m.RunWithValue(value, func(stmt *gorm.Statement) error {
 		for _, chk := range stmt.Schema.ParseCheckConstraints() {

dialects/postgres/migrator.go

@@ -108,6 +108,19 @@ func (m Migrator) HasTable(value interface{}) bool {
 	return count > 0
 }
 
+func (m Migrator) DropTable(values ...interface{}) error {
+	values = m.ReorderModels(values, false)
+	tx := m.DB.Session(&gorm.Session{})
+	for i := len(values) - 1; i >= 0; i-- {
+		if err := m.RunWithValue(values[i], func(stmt *gorm.Statement) error {
+			return tx.Exec("DROP TABLE IF EXISTS ? CASCADE", clause.Table{Name: stmt.Table}).Error
+		}); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 func (m Migrator) HasColumn(value interface{}, field string) bool {
 	var count int64
 	m.RunWithValue(value, func(stmt *gorm.Statement) error {

gorm.go

@@ -204,6 +204,7 @@ func (db *DB) SetupJoinTable(model interface{}, field string, joinTable interfac
 	if relation, ok := modelSchema.Relationships.Relations[field]; ok && relation.JoinTable != nil {
 		for _, ref := range relation.References {
 			if f := joinSchema.LookUpField(ref.ForeignKey.DBName); f != nil {
+				f.DataType = ref.ForeignKey.DataType
 				ref.ForeignKey = f
 			} else {
 				return fmt.Errorf("missing field %v for join table", ref.ForeignKey.DBName)

migrator/migrator.go

@@ -203,14 +203,11 @@ func (m Migrator) CreateTable(values ...interface{}) error {
 func (m Migrator) DropTable(values ...interface{}) error {
 	values = m.ReorderModels(values, false)
 	for i := len(values) - 1; i >= 0; i-- {
-		value := values[i]
-		if m.DB.Migrator().HasTable(value) {
-			tx := m.DB.Session(&gorm.Session{})
-			if err := m.RunWithValue(value, func(stmt *gorm.Statement) error {
-				return tx.Exec("DROP TABLE ?", clause.Table{Name: stmt.Table}).Error
-			}); err != nil {
-				return err
-			}
+		tx := m.DB.Session(&gorm.Session{})
+		if err := m.RunWithValue(values[i], func(stmt *gorm.Statement) error {
+			return tx.Exec("DROP TABLE IF EXISTS ?", clause.Table{Name: stmt.Table}).Error
+		}); err != nil {
+			return err
 		}
 	}
 	return nil

schema/relationship.go

@@ -150,6 +150,10 @@ func (schema *Schema) buildPolymorphicRelation(relation *Relationship, field *Fi
 				schema.err = fmt.Errorf("invalid polymorphic foreign keys %+v for %v on field %v", relation.foreignKeys, schema, field.Name)
 			}
 		}
+
+		// use same data type for foreign keys
+		relation.Polymorphic.PolymorphicID.DataType = primaryKeyField.DataType
+
 		relation.References = append(relation.References, &Reference{
 			PrimaryKey:    primaryKeyField,
 			ForeignKey:    relation.Polymorphic.PolymorphicID,
@@ -246,6 +250,9 @@ func (schema *Schema) buildMany2ManyRelation(relation *Relationship, field *Fiel
 
 	// build references
 	for _, f := range relation.JoinTable.Fields {
+		// use same data type for foreign keys
+		f.DataType = fieldsMap[f.Name].DataType
+
 		relation.References = append(relation.References, &Reference{
 			PrimaryKey:    fieldsMap[f.Name],
 			ForeignKey:    f,
@@ -326,6 +333,9 @@ func (schema *Schema) guessRelation(relation *Relationship, field *Field, guessH
 
 	// build references
 	for idx, foreignField := range foreignFields {
+		// use same data type for foreign keys
+		foreignField.DataType = primaryFields[idx].DataType
+
 		relation.References = append(relation.References, &Reference{
 			PrimaryKey:    primaryFields[idx],
 			ForeignKey:    foreignField,

tests/preload_suits_test.go

@@ -1167,9 +1167,8 @@ func TestNestedManyToManyPreload4(t *testing.T) {
 		}
 	)
 
+	DB.Migrator().DropTable("level1_level2", "level2_level3")
 	DB.Migrator().DropTable(&Level3{}, &Level2{}, &Level1{}, &Level4{})
-	DB.Migrator().DropTable("level1_level2")
-	DB.Migrator().DropTable("level2_level3")
 
 	dummy := Level1{
 		Value: "Level1",
@@ -1211,8 +1210,7 @@ func TestManyToManyPreloadForPointer(t *testing.T) {
 		}
 	)
 
-	DB.Migrator().DropTable(&Level2{}, &Level1{})
-	DB.Migrator().DropTable("levels")
+	DB.Migrator().DropTable("levels", &Level2{}, &Level1{})
 
 	if err := DB.AutoMigrate(&Level2{}, &Level1{}); err != nil {
 		t.Error(err)
@@ -1296,7 +1294,7 @@ func TestNilPointerSlice(t *testing.T) {
 		Level1 struct {
 			ID       uint
 			Value    string
-			Level2ID uint
+			Level2ID *uint
 			Level2   *Level2
 		}
 	)
@@ -1325,7 +1323,7 @@ func TestNilPointerSlice(t *testing.T) {
 		Level2: nil,
 	}
 	if err := DB.Save(&want2).Error; err != nil {
-		t.Error(err)
+		t.Fatalf("Got error %v", err)
 	}
 
 	var got []Level1
@@ -1481,8 +1479,7 @@ func TestPreloadManyToManyCallbacks(t *testing.T) {
 		}
 	)
 
-	DB.Migrator().DropTable(&Level2{}, &Level1{})
-	DB.Migrator().DropTable("level1_level2s")
+	DB.Migrator().DropTable("level1_level2s", &Level2{}, &Level1{})
 
 	if err := DB.AutoMigrate(new(Level1), new(Level2)); err != nil {
 		t.Error(err)