Custom equality comparer for WPF ComboBox

Question

When we bind the combobox's SelectedItem to a property, normally it will use the Equals method of the object type to determine the selected item that should be displayed in the ComboBox view. (see this question, for example)

Is it possible to have my own comparer for this, without needing to modify the class' equals method? The reason I don't want to modify the method directly is because the class is also used for business logic and I don't want my equality comparer to affect other things that use the same class

@DJ but I cannot control which implementation is passed to my viewmodel — Louis Rhys, Nov 23 '12 at 06:16
What about to use `SelectedIndex` instead of `SelectedItem`. Then you can put your custom compare logic to find the index of the item in view model. — Lubo, Nov 23 '12 at 07:51
Why not use `SelectedValue` and `SelectedValuePath` instead of `SelectedItem`? — Rachel, Nov 23 '12 at 16:52

score 1 · Answer 1 · answered Jul 22 '13 at 18:55

The reason I don't want to modify the method directly is because the class is also used for business logic and I don't want my equality comparer to affect other things that use the same class

This usually indicates a wrapper that is needed:

public class Wrapper<T>
{
    public override string ToString() { ... }

    public override bool Equals(object obj) { ... }

    public T UnderlyingRecord { get; set; }
}

This way you can carry on as normal and only the view will use the wrapper object.

Custom equality comparer for WPF ComboBox

1 Answers1