fix: tag defalut NULL and default not set should be same

migrator/migrator.go

@@ -11,6 +11,7 @@ import (
 	"gorm.io/gorm"
 	"gorm.io/gorm/clause"
 	"gorm.io/gorm/schema"
+	"gorm.io/gorm/utils"
 )
 
 var (
@@ -448,7 +449,8 @@ func (m Migrator) MigrateColumn(value interface{}, field *schema.Field, columnTy
 	}
 
 	// check default value
-	if v, ok := columnType.DefaultValue(); ok && v != field.DefaultValue {
+	if v, ok := columnType.DefaultValue(); ok &&
+		utils.CheckColumnDefaultNull(v) != utils.CheckColumnDefaultNull(field.DefaultValue) {
 		// not primary key
 		if !field.PrimaryKey {
 			alterColumn = true

tests/migrate_test.go

@@ -657,3 +657,56 @@ func TestMigrateWithSpecialName(t *testing.T) {
 	AssertEqual(t, true, DB.Migrator().HasTable("coupon_product_1"))
 	AssertEqual(t, true, DB.Migrator().HasTable("coupon_product_2"))
 }
+
+func TestUniqueColumn(t *testing.T) {
+	type UniqueTest struct {
+		ID   string `gorm:"primary_key"`
+		Name string `gorm:"unique"`
+	}
+
+	var err error
+	err = DB.Migrator().DropTable(&UniqueTest{})
+	if err != nil {
+		t.Errorf("DropTable err:%v", err)
+	}
+
+	err = DB.AutoMigrate(&UniqueTest{})
+	if err != nil {
+		t.Fatalf("AutoMigrate err:%v", err)
+	}
+
+	err = DB.AutoMigrate(&UniqueTest{})
+	if err != nil {
+		t.Fatalf("AutoMigrate err:%v", err)
+	}
+
+	AssertEqual(t, true, DB.Migrator().HasIndex(&UniqueTest{}, "name"))
+	AssertEqual(t, false, DB.Migrator().HasIndex(&UniqueTest{}, "name_1"))
+	AssertEqual(t, false, DB.Migrator().HasIndex(&UniqueTest{}, "name_2"))
+	AssertEqual(t, false, DB.Migrator().HasIndex(&UniqueTest{}, "name_2"))
+
+	type UniqueTest2 struct {
+		ID   string `gorm:"primary_key"`
+		Name string `gorm:"unique;default:NULL"`
+	}
+
+	err = DB.Migrator().DropTable(&UniqueTest2{})
+	if err != nil {
+		t.Errorf("DropTable err:%v", err)
+	}
+
+	err = DB.AutoMigrate(&UniqueTest2{})
+	if err != nil {
+		t.Fatalf("AutoMigrate err:%v", err)
+	}
+
+	err = DB.AutoMigrate(&UniqueTest2{})
+	if err != nil {
+		t.Fatalf("AutoMigrate err:%v", err)
+	}
+
+	AssertEqual(t, true, DB.Migrator().HasIndex(&UniqueTest2{}, "name"))
+	AssertEqual(t, false, DB.Migrator().HasIndex(&UniqueTest2{}, "name_1"))
+	AssertEqual(t, false, DB.Migrator().HasIndex(&UniqueTest2{}, "name_2"))
+	AssertEqual(t, false, DB.Migrator().HasIndex(&UniqueTest2{}, "name_2"))
+}

utils/utils.go

@@ -46,6 +46,13 @@ func CheckTruth(vals ...string) bool {
 	return false
 }
 
+func CheckColumnDefaultNull(val string) bool {
+	if val == "" || !strings.EqualFold(val, "NULL") {
+		return true
+	}
+	return false
+}
+
 func ToStringKey(values ...interface{}) string {
 	results := make([]string, len(values))