<telerik:GridViewDataColumn DataMemberBinding="{Binding Path=Attributes.[PERCEELID]}" Header="PerceelId" DataType="{x:Type sys:Int32}" />
First step, make ik a GridViewExpressionColumn :
<telerik:GridViewExpressionColumn UniqueName="Opp" Header="Oppervlakte (ha)" Expression="Attributes[&quot;PERCEELID&quot;]" />

So far so good, this still displays the same result as my original column (nothing calculated so far).

But as soon as I want to do something with this value, nothing is shown and I receive errors in the output window.

This is about the simplest expression I can think of (multiplying by 2) :

<telerik:GridViewExpressionColumn UniqueName="Opp" Header="Oppervlakte (ha)" Expression="Attributes[&quot;PERCEELID&quot;] * 2" />

The column stays empty and the outpunt window shows :

A first chance exception of type 'System.ArgumentException' occurred in System.ComponentModel.DataAnnotations.dll
A first chance exception of type 'System.InvalidOperationException' occurred in System.Core.dll


I have tried to explicitely cast my value first before multiplying (Convert.ToInt32(Attributes[&quot;PERCEELID&quot;]) * 2); but no success.



If I do the same in code-behind, there is no problem :

    Expression<Func<Graphic, double>> expression = g => (int)g.Attributes["PERCEELID"] * 2;
    var c = this.GevondenPercelenDataGrid.Columns["Opp"] as GridViewExpressionColumn;
    c.Expression = expression;


The ToString() of this expression yields:
 
"g => Convert((Convert(g.Attributes.get_Item(\"PERCEELID\")) * 2))"
Using this string as value for "Expression" in the xaml is no solution either.










Can anyone give me some tips on building expressions in xaml ?







 








Kind regards,







































Martin