Question

I’m data binding a list of pairs to a drop down list, for some reason it’s not working and I’m intrigued.

The code I am using is :

public void BindDropDown(List<Pair> dataList)
{
    ddlGraphType.DataTextField = "First";
    ddlGraphType.DataValueField = "Second";

    ddlGraphType.DataSource = dataList;
    ddlGraphType.DataBind();
}

I’m getting this exception, which is a lie!

DataBinding: 'System.Web.UI.Pair' does not contain a property with the name 'First'.

Thanks in advance.

Added

I know what the exception means, but a pair object does contain the First and Second properties, that’s where the problem lies.

Answer 1

First and Second are Fields not properties of Pair type. You need to create a class with two properties:

 public class NewPair
 {
    public string First { get; set; }
    public string Second { get; set; }
 }

EDIT: Use of Tuple : suggested by @Damien_The_Unbeliever & @Chris Chilvers

List<Tuple<string, string>> list = new List<Tuple<string, string>>()
 {
   new Tuple<string,string>("One","1"),
   new Tuple<string,string>("Two","2"),
};

ddlGraphType.DataTextField = "Item1";
ddlGraphType.DataValueField = "Item2";

ddlGraphType.DataSource = list;
ddlGraphType.DataBind();