feat: define new methods

migrator/migrator.go

@@ -27,6 +27,8 @@ var regFullDataType = regexp.MustCompile(`\D*(\d+)\D?`)
 
 // TODO:? Create const vars for raw sql queries ?
 
+var _ gorm.Migrator = (*Migrator)(nil)
+
 // Migrator m struct
 type Migrator struct {
 	Config
@@ -539,6 +541,26 @@ func (m Migrator) MigrateColumn(value interface{}, field *schema.Field, columnTy
 	return nil
 }
 
+func (m Migrator) MigrateColumnUnique(value interface{}, field *schema.Field, columnType gorm.ColumnType) error {
+	unique, ok := columnType.Unique()
+	if !ok || field.PrimaryKey {
+		return nil // skip primary key
+	}
+	// By default, ColumnType's Unique is not affected by UniqueIndex, so we don't care about UniqueIndex.
+	return m.RunWithValue(value, func(stmt *gorm.Statement) error {
+		// We're currently only receiving boolean values on `Unique` tag,
+		// so the UniqueConstraint name is fixed
+		constraint := m.DB.NamingStrategy.UniqueName(stmt.Table, field.DBName)
+		if unique && !field.Unique {
+			return m.DB.Migrator().DropConstraint(value, constraint)
+		}
+		if !unique && field.Unique {
+			return m.DB.Migrator().CreateConstraint(value, constraint)
+		}
+		return nil
+	})
+}
+
 // ColumnTypes return columnTypes []gorm.ColumnType and execErr error
 func (m Migrator) ColumnTypes(value interface{}) ([]gorm.ColumnType, error) {
 	columnTypes := make([]gorm.ColumnType, 0)

schema/naming.go

@@ -19,6 +19,7 @@ type Namer interface {
 	RelationshipFKName(Relationship) string
 	CheckerName(table, column string) string
 	IndexName(table, column string) string
+	UniqueName(table, column string) string
 }
 
 // Replacer replacer interface like strings.Replacer
@@ -26,6 +27,8 @@ type Replacer interface {
 	Replace(name string) string
 }
 
+var _ Namer = (*NamingStrategy)(nil)
+
 // NamingStrategy tables, columns naming strategy
 type NamingStrategy struct {
 	TablePrefix         string
@@ -85,6 +88,11 @@ func (ns NamingStrategy) IndexName(table, column string) string {
 	return ns.formatName("idx", table, ns.toDBName(column))
 }
 
+// UniqueName generate unique constraint name
+func (ns NamingStrategy) UniqueName(table, column string) string {
+	return ns.formatName("uni", table, ns.toDBName(column))
+}
+
 func (ns NamingStrategy) formatName(prefix, table, name string) string {
 	formattedName := strings.ReplaceAll(strings.Join([]string{
 		prefix, table, name,