Exposing DataGridView's columns property in UserControl doesn't work properly

Question

I put a DataGridView in a UserControl and create a public property in my usercontrol that exposes datagridview's columns property.
Here is the sample code:

public partial class UserControl1 : UserControl
{
    public UserControl1()
    {
        InitializeComponent();
    }

    public DataGridViewColumnCollection MyDataGridColumns
    {
        get
        {
            return dataGridView1.Columns;
        }
    }
}

Then I add UserControl1 in my form and I click on MyDataGridColumns property in property window and add 1 or more columns. The problem happens when I rebuild my solution; All of the columns that I have just added disappear after rebuilding.

Can anyone explain to me why this happens? and how to solve it?

Answer 1

This works for me : I created a specific columns editor as it seems it is impossible to use the default columns editor for any control that does not extend DataGridView.

public partial class UserControl1 : UserControl, IDataGridView
{
    public UserControl1()
    {
        InitializeComponent();
    }

    [DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
    [Browsable(false)]
    public DataGridView DataGridView
    {
        get { return dataGridView1; }
    }

    [DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]
    [Editor(typeof(ExtendedDataGridViewColumnCollectionEditor), typeof(UITypeEditor))]
    [MergableProperty(false)]
    public DataGridViewColumnCollection MyDataGridColumns
    {
        get { return dataGridView1.Columns; }
    }

}

public interface IDataGridView
{
    DataGridView DataGridView { get; }
}

class ExtendedDataGridViewColumnCollectionEditor : UITypeEditor
{
    private Form dataGridViewColumnCollectionDialog;

    private ExtendedDataGridViewColumnCollectionEditor() { }

    private static Form CreateColumnCollectionDialog(IServiceProvider provider)
    {
        var assembly = Assembly.Load(typeof(ControlDesigner).Assembly.ToString());
        var type = assembly.GetType("System.Windows.Forms.Design.DataGridViewColumnCollectionDialog");

        var ctr = type.GetConstructors(BindingFlags.NonPublic | BindingFlags.Instance)[0];
        return (Form)ctr.Invoke(new object[] { provider });
    }

    public static void SetLiveDataGridView(Form form, DataGridView grid)
    {
        var mi = form.GetType().GetMethod("SetLiveDataGridView", BindingFlags.NonPublic | BindingFlags.Instance);
        mi.Invoke(form, new object[] { grid });
    }

    public override object EditValue(ITypeDescriptorContext context, IServiceProvider provider, object value)
    {
        if (provider != null && context != null)
        {
            var service = (IWindowsFormsEditorService)provider.GetService(typeof(IWindowsFormsEditorService));
            if (service == null || context.Instance == null)
                return value;

            var host = (IDesignerHost)provider.GetService(typeof(IDesignerHost));
            if (host == null)
                return value;

            if (dataGridViewColumnCollectionDialog == null)
                dataGridViewColumnCollectionDialog = CreateColumnCollectionDialog(provider);

            //Unfortunately we had to make property which returns inner datagridview  
            //to access it here because we need to pass DataGridView into SetLiveDataGridView () method 
            var grid = ((IDataGridView)context.Instance).DataGridView;
            //we have to set Site property because it will be accessed inside SetLiveDataGridView () method 
            //and by default it's usually null, so if we do not set it here, we will get exception inside SetLiveDataGridView () 
            var oldSite = grid.Site;
            grid.Site = ((UserControl)context.Instance).Site;
            //execute SetLiveDataGridView () via reflection 
            SetLiveDataGridView(dataGridViewColumnCollectionDialog, grid);

            using (var transaction = host.CreateTransaction("DataGridViewColumnCollectionTransaction"))
            {
                if (service.ShowDialog(dataGridViewColumnCollectionDialog) == DialogResult.OK)
                    transaction.Commit();
                else
                    transaction.Cancel();
            }
            //we need to set Site property back to the previous value to prevent problems with serializing our control 
            grid.Site = oldSite;
        }

        return value;
    }

    public override UITypeEditorEditStyle GetEditStyle(ITypeDescriptorContext context)
    {
        return UITypeEditorEditStyle.Modal;
    }
}

Answer 2

This is because you didn't specify the type of the column. You should give the type of the column when adding a column (for example DataGridViewTextBoxColumn or DataGridViewCheckBoxColumn). In your Form1.cs do the following:

public Form1()
{
    InitializeComponent();
    DataGridViewColumn dgViewColumn = new DataGridViewTextBoxColumn();//Or DataGridViewCheckBoxColumn
    dgViewColumn.DataPropertyName = "dgViewColumn";
    dgViewColumn.HeaderText = @"dgViewColumn";
    dgViewColumn.Name = "dgViewColumn";
    userControl11.MyDataGridColumns.Add(dgViewColumn);
}