DataGridView with run-time columns

Question

I'm using C#, Windows Forms, .NET 3.5 SP1

I have a DataGridView with a lot of columns that I don't know about until run-time (i.e. I don't know I need a Foo column until run-time). To get data into and out of the cells, I'm thinking about the following architecture.

Am I on the right track, or am I missing something easier?

public interface ICustomColumn
{
    object Format (DataGridView dgv, DataGridViewCellFormattingEventArgs e);
    void Validate (DataGridView dgv, DataGridViewCellValidatingEventArgs e);
}

public class CustomDataGridView : DataGridView 
{
    protected override void OnCellFormatting (DataGridViewCellFormattingEventArgs e)
    {
        ICustomColumn col = Columns [e.ColumnIndex].Tag as ICustomColumn;
        if ( col != null )
            e.Value = col.Format (this, e);

        base.OnCellFormatting (e);
    }

    protected override void OnCellValidating (DataGridViewCellValidatingEventArgs e)
    {
        ICustomColumn col = Columns [e.ColumnIndex].Tag as ICustomColumn;
        if ( col != null )
            col.Validate (this, e);

        base.OnCellValidating (e);
    }
}

class FooColumn : ICustomColumn
{
    public FooColumn (Dictionary <RowData, Foo> fooDictionary) 
        { this.FooDictionary = fooDictionary; }

    // Foo has a meaningful conversion to the column type (e.g. ToString () for a text column
    protected object Format (DGV dgv, DGVCFEA e)
        { return FooDictionary [(RowData) dgv.Rows[e.RowIndex].DataBoundItem]; }

    // Foo has a meaningful way to interpret e.FormattedValue
    void Validate (DGV dgv, DGVCVEA e)
        { FooDictionary [(RowData) dgv.Rows[e.RowIndex].DataBoundItem].Validate (e.FormattedValue); }
}

void CreateFooColumn (DataGridView dgv)
{
    dgv.Columns.Add (new DataGridViewTextBoxColumn () { Tag = new FooColumn (fooDictionary) });
}

Answer 1

Another approach would be to use reflection.

To set up the DataGridView:

private void SetUpDataGridView()
{
    // Create the columns based on the data in the album info - get by reflection
    var ai = new AlbumInfo();
    Type t = ai.GetType();

    dataTable.TableName = t.Name;

    foreach (PropertyInfo p in t.GetProperties())
    {
        var columnSpec = new DataColumn();
        // If nullable get the underlying type
        Type propertyType = p.PropertyType;
        if (IsNullableType(propertyType))
        {
            var nc = new NullableConverter(propertyType);
            propertyType = nc.UnderlyingType;
        }
        columnSpec.DataType = propertyType;
        columnSpec.ColumnName = p.Name;
        dataTable.Columns.Add(columnSpec);
    }
}

The helper method:

private bool IsNullableType(Type theType)
{
    return (theType.IsGenericType &&
            theType.GetGenericTypeDefinition().Equals(typeof(Nullable<>)));
}

To populate the DataGridView:

private void AddToGrid(AlbumInfo info)
{
    // Add album info to table - add by reflection
    Type t = info.GetType();
    var row = new object[t.GetProperties().Length];

    int index = 0;
    foreach (PropertyInfo p in t.GetProperties())
    {
        row[index++] = p.GetValue(info, null);
    }

    dataTable.Rows.Add(row);
    dataGridView.ClearSelection();
}