How can I know what is the most sold product of a list? flutter-dart - flutter

Question

I have a list of items from the orders by date, so based on its quantity I want to find what is the most sold product.
This is the class for my items
class CartItem{
String id;
String name;
String image;
int quantity;
double price;
CartItem({
this.id,
this.name,
this.image,
this.quantity,
this.price,
});
}
For example:
List<CartItem> list = orders.products;
list.forEach((element => print('${element.name} : ${element.quantity)');
It will print:
Dress : 1
Boots : 2
Trousers : 3
Dress : 2
Trousers : 2
So based on this example, how can I get the most sold product which is 'Trousers' and the sum of its quantity which is 5 for this case.
Thank you in advance.

Answer 1

You can covert the list to a map so you can see distinct items in the list. but rather than assigning the value to the key, if the key already exists, add the value
as:
list.forEach((item) => {
map2[item.name] = item.quantity + (map2[item.name] ?? 0)
});
you will get the output:
{Dress: 3, Boots: 2, Trousers: 5}
then finally you can sort the map like this:
var sortedKeys = map2.keys.toList(growable:false)
..sort((k1, k2) => map2[k2].compareTo(map2[k1]));
LinkedHashMap sortedMap = new LinkedHashMap
.fromIterable(sortedKeys, key: (k) => k, value: (k) => map2[k]);
print(sortedMap);
sorting os mentioned here as well How to sort map value?
then you can get the first element which is the product with the highest orders
hope this helps

Answer 2

Here is another example:
// Dart 2.6.1
main() {
List list = [
{
"name":"Dress",
"quantity" : 1
},{
"name":"Boots",
"quantity" : 2
},{
"name":"Trousers",
"quantity" : 3
},{
"name":"Dress",
"quantity" : 2
},{
"name":"Trousers",
"quantity" : 2
}
];
var products={
};
String mostSelling="";
int quantity=0;
list.forEach((e) {
if(products[e["name"]]== null){
products[e["name"]]= e["quantity"];
} else {
products[e["name"]]+= e["quantity"];
}
if(products[e["name"]] >quantity){
mostSelling= e["name"];
quantity = products[e["name"]];
}
}
);
print("$mostSelling : $quantity");
}
Output: