RadFilter with custom EntityDataSource

[Justin Lorenzon]

I've been working through getting RadFilter to work with our datasource class, derived from EntityDataSource. The RadFilter throws a null ref on apply:

[NullReferenceException: Object reference not set to an instance of an object.]
   Telerik.Web.UI.RadFilter.ApplyFilterExpressonsOnDataSource() +157
   Telerik.Web.UI.RadFilter.HandleApplyCommand() +218
   Telerik.Web.UI.RadFilterCommandEventArgsFactory.HandleCommand(RadFilter ownerFilter, Object commandSource, RadFilterCommandEventArgs args) +74
   Telerik.Web.UI.RadFilter.OnBubbleEvent(Object source, EventArgs args) +319
   System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args) +37
   System.Web.UI.WebControls.Button.OnCommand(CommandEventArgs e) +125
   System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +167
   System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10
   System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13
   System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +36
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +5563

After working through all our modifications to try and figure out what was causing this by process of elimination I was disappointed to find that the RadFilter simply throws it on ANY derived DataSource. All you need to do is create an empty class which extends EntityDataSource, point a RadFilter at it, and it fails to apply with the above exception.

Is there a way to work around this?

[Iana Tsolova]

Hi Justin,

Currently RadFilter can be integrated only with LinqDataSource, EntityDataSource and OpenAccessDataSource. It does not provide support for inherited data source controls.
To overcome the issue, you can try handling the ApplyExpressions event manually.

Kind regards,
Iana
the Telerik team

[Justin Lorenzon]

Hi Iana thanks for the reply.
I will have to use the workaround you suggest for now but in doing so I'll also have to manually replicate the field generation you get when you hook an RF up to an entitydatasource too.

The thing is I see no reason for this limitation; any derived datasource should function indistinguishably from its base class or it's violating LSP, surely it would be a trivial change (and better OO design) to allow derived classes?

[Iana Tsolova]

Hi Justin,

RadFilter creates different filter expressions based on the type of the data source control is attached to. That is why it can work with the .NET and Telerik OpenAccess data source controls, and not with custom ones.

All the best,
Iana
the Telerik team

[jelling]

I have the same issue as the OP. To restate his question, if one creates a custom data source control that derives from a supported data source type (ex. LINQ data source), why wouldn't RadFilter see this still as a LINQ type and pass LINQ filters?

If it did that we could handle them appropriately inside the data-source control.

Since some time has passed, has this been fixed perhaps?

[Veli]

Hi jelling,

RadFilter currently does not support data source types derived from EntityDataSource and OpenAccessDataSource. DataSources derived from LinqDataSource work OK, though. Attaching a test project to demonstrate.

Veli
the Telerik team