C＃WPF比较列表 <T> 到Datagrid.ItemsSource

Question

I bound my private List<MaintenanceWindow> tempMaintenanceWindows to a Datagrid and enabled the user to edit the items in the Datagrid as well as to add new items. This works fine.

Now I thought about how to rollback the changes the user made if the window is closed without pressing the save button first. Basically, I want to compare the Datagrid.ItemsSource to the temporary List I populated like this:

foreach (MaintenanceWindow mainWin in maintenanceWindowList)
                tempMaintenanceWindows.Add(new MaintenanceWindow {from = mainWin.from, to = mainWin.to, abbreviation = mainWin.abbreviation, description = mainWin.description, hosts = mainWin.hosts });

I compare the two like so:

if (!tempMaintenanceWindows.SequenceEqual((List<MaintenanceWindow>)mainWinList.ItemsSource))

but the result of the SequenceEqual always seems to be false, although when debugging the code, they seem to be the exact same thing.

Hope someone can help. Thanks.

---

Quentin Roger provided an approach solution which works but I want to post my code which is probably not the neatest way to do it but it fits to my case of application.

So this is how I overrode the Equals method of my MaintenanceWindow object:

public override bool Equals (object obj)
        {
            MaintenanceWindow item = obj as MaintenanceWindow;

            if (!item.from.Equals(this.from))
                return false;
            if (!item.to.Equals(this.to))
                return false;
            if (!item.description.Equals(this.description))
                return false;
            if (!item.abbreviation.Equals(this.abbreviation))
                return false;
            if (item.hosts != null)
            {
                if (!item.hosts.Equals(this.hosts))
                    return false;
            }
            else
            {
                if (this.hosts != null)
                    return false;
            }

            return true;
        }

Answer 1

By default SequenceEqual will compare each item calling the equal function, do you override the equal? Otherwise it compares the memory adress for a class.

Also I encourage you to use FSharpList when you are looking for immutable list comparison.

"So in the override method do I have to compare every single field of my MaintenanceWindow class"

You have to compare every meaningful fields, yes.

Answer 2

If you declare your MaintenanceWindow like this :

As I said in my comment you have to compare every significant fields.In the following implementation I chose description, so if two MaintenanceWindow got the same description they ll be considered equals and the SequenceEquals ll work as expected.

 internal class MaintenanceWindow
 {
    public object @from { get; set; }
    public object to { get; set; }
    public object abbreviation { get; set; }

    private readonly string _description;
    public string Description => _description;

    public MaintenanceWindow(string description)
    {
        _description = description;
    }

    public string hosts { get; set; }

    public override bool Equals(object obj)
    {
        return this.Equals((MaintenanceWindow)obj);
    }

    protected bool Equals(MaintenanceWindow other)
    {
        return string.Equals(_description, other._description);
    }

    public override int GetHashCode()
    {
        return _description?.GetHashCode() ?? 0;
    }
}