package opt import ( "encoding/json" "github.com/reiver/go-erorr" ) const errNilReceiver = erorr.Error("opt: nil receiver") var _ json.Unmarshaler = new(Optional[bool]) var _ json.Unmarshaler = new(Optional[string]) // UnmarshalJSON makes it so json.Unmarshaler is implemented. func (receiver *Optional[T]) UnmarshalJSON(data []byte) error { if nil == receiver { return errNilReceiver } switch interface{}(&receiver.value).(type) { case *bool, *int64, *uint64, *string, *json.Number, json.Unmarshaler: // these are OK. default: return erorr.Errorf("opt: cannot unmarshal into something of type %T from JSON because pointer to parameterized type is ‘%T’ rather than ‘*bool’, ‘*string’, or ‘json.Unmarshaler’", receiver, &receiver.value) } { var dst T err := json.Unmarshal(data, &dst) if nil != err { return err } *receiver = Something(dst) } return nil }