Question

I’ve got a BindingSource with a BindingList<Foo> attached as the data source. I’d like to work with the BindingSource‘s Find method to look up an element. However, a NotSupportedException is thrown when I do the following, even though my data source does implement IBindingList (and no such exception is documented in MSDN):

int pos = bindingSource1.Find("Bar", 5);

I attached a short example below (a ListBox, a Button and a BindingSource). Could anybody help me getting the Find invocation working?

public partial class Form1 : Form
{
    public Form1() { InitializeComponent(); }

    private void Form1_Load(object sender, EventArgs e)
    {
        var src = new BindingList<Foo>();
        for(int i = 0; i < 10; i++)
        {
            src.Add(new Foo(i));
        }

        bindingSource1.DataSource = src;
    }

    private void button1_Click(object sender, EventArgs e)
    {
        int pos = bindingSource1.Find("Bar", 5);
    }
}

public sealed class Foo
{
    public Foo(int bar)
    {
        this.Bar = bar;
    }

    public int Bar { get; private set; }

    public override string ToString()
    {
        return this.Bar.ToString();
    }
}

Answer 1

BindingList<T> does not support searching, as is. In fact bindingSource1.SupportsSearching returns false. The Find function is there for other classes that want to implement the IBindingList interface that do support searching.

To get a value, you should do bindingSource1.ToList().Find("Bar",5);