Iterating through list of class in Dart - dart

Question

class product {
String name;
String price;
String quantity;
product({this.name, this.price, this.quantity});
}
void main() {
List<product> listofProducts = [
product(name: "A", price: "10"),
product(name: "B", price: "10"),
product(name: "C", price: "10"),
product(name: "D", price: "10"),
product(name: "E", price: "10"),
product(name: "F", price: "10")
];
print(listofProducts.indexOf(product(name: "B", price: "10")));
}
How do I find the index of the product(name: "B", price: "10") in listofProducts list.

Answer 1

since the items of your list are not primitve, they are reference types , you need to use the indexWhere method on the list
final index = listofProducts.indexWhere((product) => product.name == "B" && product.price == "10");
print(index)
this way you iterate over each element of the array of products and find the index of that item. becuase you are having reference types as items.

Answer 2

Alternative you can override == and hashCode so you change what Dart understands as equal of Product objects (default behavior is that objects are only equal if they are the same instance in memory).
By doing the following we change it so two Product objects are equal if they have the same name, price and quantity values.
import 'package:quiver/core.dart';
class Product {
String name;
String price;
String quantity;
Product({this.name, this.price, this.quantity});
#override
bool operator ==(dynamic other) {
if (other is Product) {
return other.name == name &&
other.price == price &&
other.quantity == quantity;
}
return false;
}
#override
int get hashCode => hash3(name, price, quantity);
}
void main() {
List<Product> listofProducts = [
Product(name: "A", price: "10"),
Product(name: "B", price: "10"),
Product(name: "C", price: "10"),
Product(name: "D", price: "10"),
Product(name: "E", price: "10"),
Product(name: "F", price: "10")
];
print(listofProducts.indexOf(Product(name: "B", price: "10"))); // 1
}
To implement the hashCode I can recommend use the quiver package which has the hash3 method to make it more convenient to combine the hash of 3 values.