Winforms How to Bind to a List<long> DatagridView and have it show correctly

Question

So I need to show in a Grid a list of numbers that people enter to help them double check their work. It almost works except it doesn't show the numbers. My setup is simple. I have a textbox, they enter the number, when the add button is clicked its added to a BindingList and then that is used as the datasource for the DataGridView.

So, with some help from this Stackoverflow Post I was able to get this halfway working. Unfortunately, even though it appears to add a row the Grid each time it does not correctly show the value. It shows the new rows as empty.

Here is my code.

   public partial class ManualEntry : Form
   {

    BindingList<long> ProjectIDs;
    public ManualEntry()
    {
        InitializeComponent();
        ProjectIDs = new BindingList<long>();
    }

When the add button is clicked, this gets executed.

        private void AddButton_Click(object sender, EventArgs e)
        {
            try
            {
               long temp = long.Parse(textBox1.Text);
               ProjectIDs.Add(temp);
               ProjectsGrid.DataSource = ProjectIDs;
               textBox1.Text = "";//clear the textbox so they can add a new one.
            }
            catch//bring up the badinput form
            {
                BadInput b = new BadInput();
                b.Show();
            }

        }

And so here is the result of adding a few numbers.

If you need any other code from me to help you answer the question, just ask.

Answer 1

You haven't told the DataGridViewColumn what to bind to.

Normally you bind to a public property of the bound data type. In this case your data type is long which does not have an appropriate property to bind to.

Wrap your long in a custom class and expose it as a public property.

public class Data
{
    public long Value { get; set; }
}

Bind your column to the Value property. You can do this in the designer, but here is the code:

Column1.DataPropertyName = "Value";

Now instead of long you use Data:

ProjectIDs = new BindingList<Data>();

...

long temp = long.Parse(textBox1.Text);
ProjectIDs.Add(new Data { Value = temp });

Answer 2

The following post discusses this:

DataGridView bound to BindingList does not refresh when value changed

It looks like your data type in the binding list needs to support the INotifyPropertyChanged interface:

http://msdn.microsoft.com/en-us/library/system.componentmodel.inotifypropertychanged.aspx

NOTE: Revised - my use of INotifyPropertyChanged was incorrect and also appears not to be needed. Now this answer is basically just like Igby's - so I think his is the better one :)

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
   public partial class Form1 : Form
   {
      public Form1()
      {
         InitializeComponent();
         ProjectIDs = new BindingList<AwesomeLong>();
         var source = new BindingSource( ProjectIDs, null );
         dataGridView1.DataSource = source;
         dataGridView1.Columns.Add( new DataGridViewTextBoxColumn() );
      }

      BindingList<AwesomeLong> ProjectIDs;
      private int i = 0;
      private void button1_Click( object sender, EventArgs e )
      {
         i++;
         ProjectIDs.Add(new AwesomeLong(i));
      }

   }

   public class AwesomeLong
   {
      public long LongProperty { get; set; }

      public AwesomeLong( long longProperty )
      {
         LongProperty = longProperty;
      }    
   }
}