Data Access and ObjectDataSource Control

Re: return value from LINQ query

bhadelia.imran — Sun, 05 Jul 2009 00:22:20 GMT

(From r In dc.tblReunion_Infos _
Where r.ReunionIndex = strQS _
Select r.ReunionYear, r.ReunionIndex).FirstOrDefault()

There must be FirstOrDefault function, please check it again.

Without making call to any ToList, First, FirstOrDefault, query cant get execute, First of FirstOrDefault will returns the first element after executing your query.

Re: return value from LINQ query

muybn — Sat, 04 Jul 2009 19:46:42 GMT

Thanks for your efforts, but it didn't like the "FirstOrDefault" after the final parenthesis; the closest I could get was the following, which still returned the same error as listed in my first entry.

Dim strQS As String = Request.QueryString("index")
lbl = Util.FindChild(Page, "lblEntry")
Dim dc As alumniDataContext = New alumniDataContext
Dim data As New tblReunion_Info '= New tblReunion_Info
data = (From r In dc.tblReunion_Infos _
   Where r.ReunionIndex = strQS _
   Select r.ReunionYear.FirstOrDefault, r.ReunionIndex)
lbl.Text = data.ReunionYear

Re: return value from LINQ query

JMayo — Sat, 04 Jul 2009 17:18:00 GMT

Hi,

Try this:

04.data = (From r In dc.tblReunion_Infos _   
05. Where r.ReunionIndex = Request.QueryString("index") _   
06. Select r.ReunionYear, r.ReunionIndex).FirstOrDefault

Your query returns an IQueryable(Of Customer), which is a collection and you need to either iterate through it with a for/for each loop or use a query operator like FirstOrDefault to extract the one item you need.

Joe

return value from LINQ query

muybn — Sat, 04 Jul 2009 09:22:46 GMT

I want to set a label's text equal to a value I return from a LINQ query, as follows:

        Dim dc As New alumniDataContext
        Dim data As tblReunion_Info
        lbl = Util.FindChild(Page, "lblEntry")
        data = (From r In dc.tblReunion_Infos _
         Where r.ReunionIndex = Request.QueryString("index") _
         Select r.ReunionYear, r.ReunionIndex)
        lbl.Text = data.ReunionYear

Following is the error I receive, which obviously means that I have to do some converting somewhere. Your help will be appreciated.

Unable to cast object of type 'System.Data.Linq.DataQuery`[System.String,System.Int32]' to type 'tblReunion_Info'."