column.Template with expressions in Q1 2010

[cheburek]

Hello
I'm using the Q1 2010 of Telerik controls for ASP .Net MVC and stuck with next when on adding columns to grid:

Following code worked in Q3 2009 version (I have removed such things as Encoded(false) in samples):

columns.Add ( s => String.IsNullOrEmpty ( s.StringVar1 )
                    ? s.StringVar2
                    : Html.ActionLink<SomeController> ( x => x.Title ( s.Var3 ), s.StringVar1, null ) );

With Q1 version that code I've changed first to:

columns.Bound ( s => String.IsNullOrEmpty ( s.StringVar1 )
                    ? s.StringVar2
                    : Html.ActionLink<SomeController> ( x => x.Title ( s.Var3 ), s.StringVar1, null ) );

but got telerik exception "Bound columns require a field or property access expression."
And after that changed to template:

columns.Template ( s => String.IsNullOrEmpty ( s.StringVar1 )
                    ? s.StringVar2
                    : Html.ActionLink<SomeController> ( x => x.Title ( s.Var3 ), s.StringVar1, null ) );

but get compile error: "Only assignment, call, increment, decrement and new object expressions can be used as a statement"

I think that it is possible to wrap that condition to the html helper and return only string - something like this:

columns.Template ( Html.MyWrapHelper<SomeController> ( x => x.Title ( s.Var3 ), s.StringVar1, null ) );

but this is very simple example and in more complex cases there will be many helpers with functionality where hardly to understand there difference.

So the question: Is it possible to work with column.Template(...) where between parenthesis present not a string but expression which returns string (see examples above)?

Thanks

[Atanas Korchev]

Hello cheburek,

The Template column expect and Action which should not return a result. Rather it should output its value to HTML:

columns.Template ( s =>
{
if (String.IsNullOrEmpty ( s.StringVar1 ) ) {
%>
<%= s.StringVar2 %>
<%
} else {
%>
<%= Html.ActionLink<SomeController> ( x => x.Title ( s.Var3 ), s.StringVar1, null ) %>
<%
}
});

All the best,
Atanas Korchev
the Telerik team

Do you want to have your say when we set our development plans? Do you want to know when a feature you care about is added or when a bug fixed? Explore the Telerik Public Issue Tracking system and vote to affect the priority of the items.

[Rodolfo Gonzalez]

I would just like to add how to use the colum.template funcionality in VB.NET 2008 because only up until VB 2010 can lambda expressions be decaulred as Sub instead of as Functions.

I was basing my code on Atanas' helpful post regarding VB.NET coding for the MVC grid (http://www.telerik.com/community/forums/aspnet-mvc/grid/mvc-grid-using-vb-net.aspx), but it doesn't explain or show how to use the template function.

So I was desperately trying to make this work:

gridBuilder.Columns(Function(columns) columns.Bound(Function(o) o.mtikNumero) _
.Title("Ticket #") _
.Template(Function(o) Html.ActionLink(o.mtikNumero, "Ticket", New With {.id = o.mtikId})))

And then I understood that the template function actually has to write the string you compose to the response buffer.

This is easily doable on VB 2010 because it now supports lamdas that don't return a value (as in .Template(Sub(x) Response.Write(x.field))...

But not on VB 2008... 

So after tinkering around, I was able to trick the rendering enginge with this code:

<script runat="server">
    '...page load and declarations go here...

    Protected Function TrickWrt(ByVal s As String) As String
        Response.Write(s)
        Return ""
    End Function
</script>

gridBuilder.Columns(Function(columns) columns.Bound(Function(o) o.mtikNumero) _
.Title("Ticket #") _
.Template(Function(o) TrickWrt(Html.ActionLink(o.mtikNumero, "Ticket", New With {.id = o.mtikId}).ToHtmlString)))

I hope this helps others using VB 2008 trying to use Telerik's MVC extensions...

[Niladri]

hi,
please can you provide the same code for razor engine

columns.Template(u =>{
if (u.Status == 3){
@<img alt="Processed" src="@Url.Content("~/Content/Images/1-done2.png")/>
}
else if (u.Status == 1){
@<img alt="In Process" src="@Url.Content("~/Content/Images/1-done3.png")/>
}
}).Width(50).HtmlAttributes(new { style = "text-align:center" })

This gives me an error :

Compiler Error Message: CS1002: ; expected

Source Error:

Line 83: Line 84: @<img alt="Processed" src="@Url.Content("~/Content/Images/1-done2.png")" /> Line 85: Line 86: } Line 87: