"Invalid group by expression: Group By clause missing" error when grouping a GridTemplateColumn

[Joe Kalinowski]

I receive a "Invalid group by expression: Group By clause missing" when grouping a GridTemplateColumn. However, if I set that same column as a GridBoundColumn, grouping works correctly. Also, if I set the GridTemplateColumn to be grouped by default the GroupByExpressions collection, it is grouped properly, but then if I remove the grouping and drag the column to be grouped again, it fails with the same error.

If I remove the GroupByExpression from the GridTemplateColumn definition and try to group by dragging, I get a "Telerik.Web.UI.GridGroupByException: Expression cannot be null or empty" error.

GridBoundColumn definition that works:

<

 

 

telerik:GridBoundColumn

 

 

 

UniqueName="School1"

 

 

 

SortExpression="School"

 

 

 

DataField="School"

 

 

 

HeaderText="School"

 

 

 

AllowFiltering="true"

 

 

 

Groupable="true"

 

 

 

HeaderStyle-Width="75"

 

 

 

ItemStyle-Width="75"

 

 

 

FooterStyle-Width="75"/>

 

GridTemplateColumn defination that fails (with GroupByExpression="School" I get "Invalid group by expression: Group By clause missing" and without it I get "Telerik.Web.UI.GridGroupByException: Expression cannot be null or empty":

<

 

 

telerik:GridTemplateColumn

 

 

 

UniqueName="School2"

 

 

 

SortExpression="School"

 

 

 

DataField="School"

 

 

 

HeaderText="School"

 

 

 

AllowFiltering="true"

 

 

 

Groupable="true"

 

 

 

HeaderStyle-Width="75"

 

 

 

ItemStyle-Width="75"

 

 

 

FooterStyle-Width="75">

 

 

 

<ItemTemplate>

 

<%

 

# Eval("School") %>

 

 

 

</ItemTemplate>
</telerik:GridTemplateColumn>

 

[Joe Kalinowski]

So it appears that my syntax for the GroupByExpression property was incorrect. It should be GroupByExpression="School Group By School" instead of

 

GroupByExpression

 

 

="School". So the question is - why is a GroupByExpression required for a GridTemplateColumn but not a GridBoundColumn?

[Mira]

Hello Joe,

Please try setting GroupByExpression="School Group By School"  to the template column and let me know whether it helps.

Greetings,
Mira
the Telerik team

[Joe Kalinowski]

Yes, it did fix the issue. According to the documentation, this should not be necessary. And it is not necessary with a GridBoundColumn.

From the documentation:
The group-expression that should be used when grid is grouping-by this column. If not set explicitly, RadGrid will generate a group expression based on the DataField of the column (if available), using the GridColumn.GetDefaultGroupByExpression method.

[Joe Kalinowski]

Can a format string be included in the GroupByExpression syntax? I don't see anything about that in the documentation.

[Mira]

Hello Joe,

Straight to your questions:

1. The cited functionality is valid for all columns except the template ones. I have notified our help team about this lapse in the documentation and they are already  working on it.
2. The desired behavior can be implemented using the FormatString property.

I hope this helps.

Sincerely yours,
Mira
the Telerik team

[Dave]

This solution worked for me too.  Thx!  :)