How to set values into custom DataGridBound column in WPF

Question

Since there is no way to paste values into a DataGridTemplateColumn. I found some suggestions for creating my own column class derived from DataGridBoundColumn. The sample below adds a DatePicker to the column without using a template.

However this sample does not allow me to manually set a value using the DatePicker and I'm not sure why. I'm thinking there is something with the binding. It will load date values that I bind to it initially so it's halfway there.

Interestingly enough using some other helper classes I'm able to paste dates as well which was the origianl purpose. I just didn't want to break anything else. :-)

Any ideas how to make the datepicker selected value bind properly?

class MyDateColumn : DataGridBoundColumn 
{

    public string DateFormat { get; set; }
    protected override void CancelCellEdit(FrameworkElement editingElement, object uneditedValue)
    {
        DatePicker dp = editingElement as DatePicker;
        if (dp != null)
        {
            dp.SelectedDate = DateTime.Parse(uneditedValue.ToString());
        }
    }
    protected override FrameworkElement GenerateEditingElement(DataGridCell cell, object dataItem)
    {
        DatePicker dp = new DatePicker();
        Binding b = new Binding();
        Binding bb = this.Binding as Binding;
        b.Path = bb.Path;
        b.Source = DatePicker.SelectedDateProperty;
        if (DateFormat != null)
        {
            DateTimeConverter dtc = new DateTimeConverter();
            b.Converter = dtc;
            b.ConverterParameter = DateFormat;
        }
        dp.SetBinding(DatePicker.SelectedDateProperty, this.Binding);

        return dp;
    }

    protected override FrameworkElement GenerateElement(DataGridCell cell, object dataItem)
    {
        TextBlock txt = new TextBlock();
        Binding b = new Binding();
        Binding bb = this.Binding as Binding;
        b.Path = bb.Path;
        b.Source = cell.DataContext;

        if (DateFormat != null)
        {
            DateTimeConverter dtc = new DateTimeConverter();
            b.Converter = dtc;
            b.ConverterParameter = DateFormat;
        }
        txt.SetBinding(TextBlock.TextProperty, this.Binding);
        return txt;
    }

    protected override object PrepareCellForEdit(FrameworkElement editingElement, RoutedEventArgs editingEventArgs)
    {
        DatePicker dp = editingElement as DatePicker;
        if (dp != null)
        {
            DateTime? dt = dp.SelectedDate;
            if (dt.HasValue)
                return dt.Value;
        }
        return DateTime.Today;
    }

    protected override bool CommitCellEdit(FrameworkElement editingElement)
    {
        DatePicker dp = editingElement as DatePicker;
        dp.SelectedDate = DateTime.Today.AddYears(1);

        return true;
        //return base.CommitCellEdit(editingElement);
    }


}

Answer 1

The solutions is a modification to CommitCellEdit()...

    protected override bool CommitCellEdit(FrameworkElement editingElement)
    {
        DatePicker dp = editingElement as DatePicker;
        DateTime dt;
        try
        {
            dt = Convert.ToDateTime(dp.Text);
            dp.SelectedDate = dt;
        }
        catch (FormatException)
        {
            dp.Text = String.Empty;
        }


        BindingExpression binding = editingElement.GetBindingExpression(DatePicker.SelectedDateProperty);
        if (binding != null)
            binding.UpdateSource();
        return true;
        //return base.CommitCellEdit(editingElement);
    }

Original code and help comes from the following link...

http://leeontech.wordpress.com/2009/01/21/creating-datagriddatecolumn-for-datagrid/#comment-1033

Thanks for creating the sample and the help Lee!