How to extract DataItem column in NodeDataBound when based on EF object?

[Erik Lidman]

Hi,

I have a RadTreeView that is populated with data using linq;
---

var sobjects = from so in context.Source

                           select new { so.ID, so.Name, so.Parent_ID, StatusID=so.Status_1.ID };

            SourceRadTreeView.DataSource = sobjects;

---
I then want to extract the StatusID value in the NodeDataBound event for each node.

e.Node.ToolTip = (e.Node.DataItem as DataRow)["StatusID"].ToString();

(as according to documentation)
But then I get;
Object reference not set to an instance of an object.

Solution?
/Erik Lidman

[Cori]

Hello Erik,

When it comes to binding using LINQ or EF, the DataItem is of the type you bound the data to. I notice you are creating an annoymous class, since your selecting the fields you want to display, but if you can select all the fields, returning a list of Source elements then you can implement it the following way, otherwise you can create a class that has those fields, so you can cast the DataItem object correctly. So if you use a list of Source objects you would cast the DataItem to Source, instead of a DataRow because DataRow is when your binding using SqlDataSource or a table object.

So your code would look like this instead:

e.Node.ToolTip = (e.Node.DataItem as Source).Status_1.ID.ToString();

I hope that helps.

[Erik Lidman]

Hi,
Thanx for your reply.
I still have problems. After two hours of trying out a lot of different linq statements I still cant get it to work.

I put in the object Source (which is related to the entity Status).
In the NodeDataBound comes the object Source fine, but without the related information about Status.
/Erik

var sobjects =  from so in context.Source
select so;

 

SourceRadTreeView.DataSource = sobjects;

--------------------------------------------------------------------------------- 

protected void SourceRadTreeView_NodeDataBound(object sender, RadTreeNodeEventArgs e)

        {

            

            e.Node.ToolTip = (e.Node.DataItem as Source).Status.ID.ToString();

[Yana]

Hi Erik,

We cannot reproduce the issue with the provided code. Can you please open a support ticket and send us simple runnable project (we don't need the whole database) demonstrating the problem? Thanks in advance

Kind regards,
Yana
the Telerik team

[Erik Lidman]

Solved it...
The linq query must return a shaped result, like this.

var sobjects =  from so in context.Source.
                               Include("Status").
                               Include("SourceType")
                            select so;

Case closed,
/Erik