Implement route rules

option/listable.go

@@ -0,0 +1,27 @@
+package option
+
+import "encoding/json"
+
+type Listable[T any] []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
+}