(Dynamically) Implement ToString() as a Lambda Function

Background

You’d like to manually populate a combo box with a collection of 3^rd party objects. These objects do not have a display property to bind to, are sealed, and already use ToString() for another purpose.

The Code

The solution to this problem is to use generics and lambda function to dynamically wrap your class and add a custom function to it.

public class Stringable<T>
{
    private T _obj;
    private Func<T, string> _convertFn;
    public Stringable(T obj, Func<T, string> convertFn)
    {
        _obj = obj;
        _convertFn = convertFn;
    }
    public T GetObj() { return _obj; }
    public override string ToString() { return _convertFn(_obj); }
}

This class will allow you to wrap an object and use lambda function to dynamically implement ToString() from its’ properties.

Stringable<CustomerModel> customerItem = new Stringable<CustomerModel>(customer, c => c.Name);

You can now pass customerItem to your combo box. And, finally, when the user selects a combo box item, you can recall the original object like this:

CustomerModel selCustomer = (cbo.SelectedItem as Stringable<CustomerModel>).GetObj();