existItem method

bool existItem(
  1. String id
)

API to check the item is existing or not.

Parameters:
id Unique ID to be checked.

Exceptions:
Throws an ArgumentError if ID is empty.

Return 'true' or 'false'

Implementation

bool existItem(String id) {
  if (id.isEmpty) {
    throw ArgumentError("You must set id.");
  } else if (items!.isEmpty) {
    throw ArgumentError("You don't have any item.");
  } else {
    final index = items!.indexWhere((items) => items.id == id);
    if (index == -1) return false;
    return true;
  }
}