My dirty solution for so far.

I extend the WebDateChooserProvider class and override the method bool CanEditType(Type t).

This method return now true if it's a datetime field, nullable datetime field or a string. Why the string is necessary? I don't know but it works. When by a string type return false the grid will be display an error if I bind an empty list. I use linq for my database connection and I cast the result recordset to a List<Data model object>.

public class NullableDateTimeEditorProvider : Infragistics.Web.UI.GridControls.WebDateChooserProvider
    {
        protected override bool CanEditType(Type t)
        {
            if (t.Name.Contains("Nullable"))
            {
                return t.FullName.Contains("System.DateTime");  // Nullable datetime support!
            }
            else if (t.Name.Contains("String"))
            {
                return true;                                    // Strings also true. Why? Read the description
            }
            else
            {
                return base.CanEditType(t);                     // Otherwise check the base method
            }
        }
    }

How you you use this NullableDataTimeEditorProvider solution to replace the WebDateChooserProvider?  Is there a way to do it in the design mode or must it be done programmatically (add the provider during run time).

Thanks
ROB

My solution is to implement a class that extends WebDateTimeEditProvider. See my code example earlier in this thread.

In the aspx file you add the NullableDateTimeEditorProvider tag in the EditorProviders tag. 

<ext:NullableDateTimeEditorProvider ID="datefield" />

Instead the default WebDateTimeEditProvider .

<ig:WebDateTimeEditProvider id="datefield" />

And you need to register the assembly of the NullableDateTimeEditorProvider in the top of the aspx file.

<%

@ Register Assembly="InfragisticsExtensions" Namespace="InfragisticsExtensions" TagPrefix="ext" %>

I had the exact same problem described above, except with WebNumericEditProvider. First I implemented a custom editor provider as suggested that returned "true" for "System.String" too. But this seemed a like hack to me, so I started to check both the code and the markup and found out the following.

1. You need to specify the DataType attribute on every column you want to make editable.

<ig:BoundDataField DataFieldName="MonthValue1"

Key="MonthValue1" Width="60px" DataFormatString="{0:N2}" DataType="System.Decimal">

</ig:BoundDataField>

2. Wire-up the editor provider with the column in markup

<ig:EditingCore>

      <Behaviors>

            <ig:CellEditing>

                  <ColumnSettings>

                       ...                                           

<ig:EditingColumnSetting ColumnKey="MonthValue1" EditorID="wtnpEffortEditorProvider" />

...

                  </ColumnSettings>

            </ig:CellEditing>

      </Behaviors>

</ig:EditingCore>

I'm not sure you _need_ to do it in the markup, I assume the same would work from code-behind, but I had no time to check.

Hope this helps.