package option import "encoding/json" type Listable[T comparable] []T func (l *Listable[T]) MarshalJSON() ([]byte, error) { arrayList := []T(*l) if len(arrayList) == 1 { return json.Marshal(arrayList[0]) } return json.Marshal(arrayList) } func (l *Listable[T]) UnmarshalJSON(bytes []byte) error { err := json.Unmarshal(bytes, (*[]T)(l)) if err == nil { return nil } var singleItem T err = json.Unmarshal(bytes, &singleItem) if err != nil { return err } *l = []T{singleItem} return nil }