C# GUI control for editing a Dictionary

Question

Is there a standard control that lets a user edit the key-value pairs of a String to String Dictionary?

If not, how would you implement one? I've got a few ideas but none of them seems great.

Answer 1

No, there isn't one built in. For implementing one; how about a 2-column DataGridView, implementing IDataErrorInfo such that duplicated keys result in a red error blob:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Windows.Forms;
class Pair : IDataErrorInfo
{
    internal IList<Pair> Parent { get; set; }
    public string Key { get; set; }
    public string Value { get; set; }

    string IDataErrorInfo.Error
    {
        get { return ""; }
    }

    string IDataErrorInfo.this[string columnName]
    {
        get
        {   
            if(columnName == "Key" && Parent != null && Parent.Any(
                x=> x.Key == this.Key && !ReferenceEquals(x,this)))
            {
                return "duplicate key";
            }
            return "";        
        }
    }
}

static class Program
{
    [STAThread]
    static void Main()
    {
        Application.EnableVisualStyles();
        BindingList<Pair> pairs = new BindingList<Pair>();
        // todo: fill from StringDictionary
        pairs.AddingNew += (s,a) =>
        {
            a.NewObject = new Pair { Parent = pairs };
        };
        Application.Run(new Form {
            Controls = {new DataGridView {
                Dock = DockStyle.Fill,
                DataSource = pairs
            }}
        });
    }
}

Answer 2

Just make a list and databind them to a grid. Quick & easy.

EDIT: here's an example, assumed you have a form with a GridView on it.

Dictionary<string, string> d;
protected void Page_Load(object sender, EventArgs e)
{
d = new Dictionary<string, string>();
d.Add("key 1", 1);
d.Add("key 2", 2);
d.Add("key 3", 3);
d.Add("key 4", 4);
d.Add("key 5", 5);

GridView1.DataSource = d;
GridView1.DataBind();

}

For error handling etc, check Marc's answer. You might also want to do some more research on DataBinding.