[Solved] complex expressions in columns doesn't work

[Manuel Vögele]

Hi!

A modification of the Telerik-CustomBinding-Example will show you what I mean with "complex expressions in columns doesn't work".

    <%= Html.Telerik().Grid(Model)
            .Name("Grid")
            .Columns(columns =>
            {
                columns.Add(o => o.OrderID).Width(100);
                columns.Add(o => o.Customer.ContactName + "AppendThisString").Width(200);
                columns.Add(o => o.ShipAddress);
                columns.Add(o => o.OrderDate).Format("{0:MM/dd/yyyy}").Width(100);
            })
            .RowAction( row => row.HtmlAttributes[ "id" ] = row.DataItem.OrderID )
            .Ajax(settings => settings.Action("_CustomBinding", "Grid"))
            .Pageable(settings => settings.Total((int)ViewData["total"]))
            .EnableCustomBinding(true)
            .Sortable()
    %>

I only changed the line where the second column is defined and added "+ "AppendThisString"" to the existing lambda expression. Now it's more then a simple property. At the first look it seems to work, but if I change the page and load new data by ajax, the secound column will not execute the expression and so the old data are still shown in this column.

By the way... the same happens with the row-id-tag (calculated by the RowAction-expression). If you change the page, the id of the row is still old, too.

Any ideas?

Greetings

Manuel

[Atanas Korchev]

Hi Manuel Vögele,

Indeed we support only simple expressions - member access only (field and property access). This means that no operators or method invocations will work. The reason is very simple - we serialize those and use them in client-side binding (ajax or web service). Our expression engine expects "Customer.ContactName" and does not know what to do with "Customer.ContactName + AppendThisTring". For example we cannot sort by this expression since there is no such property. If you just want to customize the way the data is output in the row you can use the Format property:

columns.Add(o => o.Customer.ContactName).Format("{0}AppendThisString");

The problem with the RowAction stems from the fact that those attributes are rendered server side. When performing client-side binding they are not updated. In a word there is no way to map C# code to JavaScript thus we cannot apply the RowAction on the client-side. As a workaround you can use the OnRowDataBound client-side event:

.ClientEvents(c => c.OnRowDataBound("onRowDataBound"))
        .Pageable()
        .Sortable()
        .Filterable()
%>

<script type="text/javascript">
function onRowDataBound(e) {
    e.row.id = e.dataItem.OrderID;
}
</script>

Regards,
Atanas Korchev
the Telerik team

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[Manuel Vögele]

It works...

Thanks