package dto

import "encoding/json"

type NullString struct {
	String string
	IsNull bool
}

// Serialization
func (ns NullString) MarshalJSON() ([]byte, error) {
	// If Valid is true, return the JSON serialization result of String.
	if ns.IsNull {
		return []byte(`"` + ns.String + `"`), nil
	}
	// If Valid is false, return the serialization result of null.
	return []byte("null"), nil
}

// Deserialization
func (ns *NullString) UnmarshalJSON(data []byte) error {
	// If data is null, set Valid to false and String to an empty string.
	if string(data) == "null" {
		ns.String, ns.IsNull = "", false
		return nil
	}
	// Otherwise, deserialize data to String and set Valid to true.
	if err := json.Unmarshal(data, &ns.String); err != nil {
		return err
	}
	ns.IsNull = true
	return nil
}