comparing two lists in linq

Question

I have two lists: orders and items and I need to compare them by their name AND then look if order list have bool set to false and if it satysfy the condition it copies its string message and then adds to new list and I just have no freaking idea even how to compare lists, so any help will be appreciated Function:

 private static void FailedItemsList(List<Item> failed, List<Order> orders, List<Item> items)
{
    foreach(var order in orders)
    {
        foreach(var item in items)
        {
            if(order.Equals(item))
            {
                if(order.Fulfilled == false)
                {
                    item.FailMessage = order.FailMessage;
                    failed.Add(item);
                }
            }
        }
    }
}

I forgot to say that Equals compares order.Name to item.Name, so in linq i need that it would compare thei names and if it matches then check if order.Fulfilled == false and if it is then item should copy FailMessage and add that item to new list, I know its a big mess but thats the thing i was asked :( — Donatas
– Donatas, Commented May 25, 2016 at 7:43
Are you sure that your code works, Order is a different class than Item but you are using order.Equals(item)? — Tim Schmelter
– Tim Schmelter, Commented May 25, 2016 at 7:48
Yeah it works, because It was public class Order : IEquatable<Item> and had Equals method, who compared and your GetFailedItems method worked just fine, tanks — Donatas
– Donatas, Commented May 25, 2016 at 9:42

Tim Schmelter · Accepted Answer · 2016-05-25 07:59:07Z

In general i would return this "fail-list" from the method instead of passing it to it. You could use LINQ to simplify this task:

static List<Item> GetFailedItems(List<Order> orders, List<Item> items)
{
    var failed = from order in orders
                 where !order.Fulfilled
                 join item in items on order.Name equals item.Name
                 select new { order, item};

    List<Item> failedItems = new List<Item>();
    foreach (var x in failed)
    {
        x.item.FailMessage = x.order.FailMessage;
        failedItems.Add(x.item);
    }

    return failedItems;
}

Since Item and Order are different classes i have removed the Equals check and replaced it with a join on the Name property as desired. Since LINQ should not cause side effects i haven't modifed the Item.FailMessage property in the query but in the foreach-loop. Due to LINQ's deferred execution(the query gets executed at the foreach) this is not less efficient.

Vishal Suthar · Accepted Answer · 2016-05-25 08:44:54Z

0

var v = from x in orders
        where x.Fulfilled == false
        join item in items on order.Name equals item.Name
        select x.FailMessage;

foreach (int i in v)
    failed.Add(i);

edited May 25, 2016 at 8:44

answered May 25, 2016 at 7:46

Vishal Suthar

17.2k4 gold badges64 silver badges109 bronze badges

Collectives™ on Stack Overflow

comparing two lists in linq

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related