field.DataType = ""
			field.IgnoreMigration = true
		case "migration":
			field.IgnoreMigration = true
		}
	}

	if v, ok := field.TagSettings["->"]; ok {
		field.Creatable = false
		field.Updatable = false
		if strings.ToLower(v) == "false" {
			field.Readable = false
		} else {
			field.Readable = true
		}
	}

	if v, ok := field.TagSettings["<-"]; ok {
		field.Creatable = true

	Value(ctx context.Context, field *Field, dst reflect.Value, fieldValue interface{}) (interface{}, error)
}

// JSONSerializer json serializer
type JSONSerializer struct{}

// Scan implements serializer interface
func (JSONSerializer) Scan(ctx context.Context, field *Field, dst reflect.Value, dbValue interface{}) (err error) {
	fieldValue := reflect.New(field.FieldType)

	if dbValue != nil {
		var bytes []byte

}

// ParseUniqueConstraints parse schema unique constraints
func (schema *Schema) ParseUniqueConstraints() map[string]UniqueConstraint {
	uniques := make(map[string]UniqueConstraint)
	for _, field := range schema.Fields {
		if field.Unique {
			name := schema.namer.UniqueName(schema.Table, field.DBName)
			uniques[name] = UniqueConstraint{Name: name, Field: field}
		}
	}
	return uniques

		} else {
			mapValue[column] = nil
		}
	}
}

func (db *DB) scanIntoStruct(rows Rows, reflectValue reflect.Value, values []interface{}, fields []*schema.Field, joinFields [][]*schema.Field) {
	for idx, field := range fields {
		if field != nil {
			values[idx] = field.NewValuePool.Get()
		} else if len(fields) == 1 {
			if reflectValue.CanAddr() {
				values[idx] = reflectValue.Addr().Interface()
			} else {

	stmt := gorm.Statement{DB: DB}
	if err := stmt.Parse(&EngadgetPost{}); err != nil {
		t.Fatalf("failed to parse embedded struct")
	} else if len(stmt.Schema.PrimaryFields) != 1 {
		t.Errorf("should have only one primary field with embedded struct, but got %v", len(stmt.Schema.PrimaryFields))
	}

	for _, name := range []string{"user_id", "user_name", "user_email"} {
		if !DB.Migrator().HasColumn(&HNPost{}, name) {

	expr.SQL = m.DataTypeOf(field)

	if field.NotNull {
		expr.SQL += " NOT NULL"
	}

	if field.HasDefaultValue && (field.DefaultValueInterface != nil || field.DefaultValue != "") {
		if field.DefaultValueInterface != nil {
			defaultStmt := &gorm.Statement{Vars: []interface{}{field.DefaultValueInterface}}
			m.Dialector.BindVarTo(defaultStmt, defaultStmt, field.DefaultValueInterface)

				}
			}

			for _, name := range []string{f.DBName, f.Name} {
				if name != "" {
					if field := s.LookUpField(name); field == nil || (field.Name != name && field.DBName != name) {
						t.Errorf("schema %v failed to look up field with dbname %v", s, f.DBName)
					}
				}
			}

			if f.PrimaryKey {
				var found bool

				field := stmt.Schema.FieldsByDBName[column.Name]
				if values.Values[0][idx], isZero = field.ValueOf(stmt.Context, stmt.ReflectValue); isZero {
					if field.DefaultValueInterface != nil {
						values.Values[0][idx] = field.DefaultValueInterface
						stmt.AddError(field.Set(stmt.Context, stmt.ReflectValue, field.DefaultValueInterface))
					} else if field.AutoCreateTime > 0 || field.AutoUpdateTime > 0 {

	// Columns
	AddColumn(dst interface{}, field string) error
	DropColumn(dst interface{}, field string) error
	AlterColumn(dst interface{}, field string) error
	MigrateColumn(dst interface{}, field *schema.Field, columnType ColumnType) error
	// MigrateColumnUnique migrate column's UNIQUE constraint, it's part of MigrateColumn.
	MigrateColumnUnique(dst interface{}, field *schema.Field, columnType ColumnType) error

}

// FieldNewValuePool field new scan value pool
type FieldNewValuePool interface {
	Get() interface{}
	Put(interface{})
}

// CreateClausesInterface create clauses interface
type CreateClausesInterface interface {
	CreateClauses(*Field) []clause.Interface
}

// QueryClausesInterface query clauses interface
type QueryClausesInterface interface {
	QueryClauses(*Field) []clause.Interface
}