ASP.NET Select Method Using Entity framework Stored Procedure

Question

I have ListView like this

<asp:ListView ID="ListView1" ItemType="test.Project"  
     SelectMethod="ListView1_GetData" runat="server">

I am trying to set the select method to a stored procedure using EF. the select method like this

public IQueryable<Test.Project> ListView1_GetData()
{
    using (DREntities2 db=new DREntities2())
    {
        return db.GetLatestProjects().AsQueryable();
    }
}

I get this error:

Cannot implicitly convert type 'System.Linq.IQueryable' to 'System.Linq.IQueryable'. An explicit conversion exists (are you missing a cast?)

If I remove the .AsQueryable(), I get this error:

Cannot implicitly convert type 'System.Data.Objects.ObjectResult' to 'System.Linq.IQueryable

Here is the definition of the GetLastestProjects_Result as returned by DREntities2 .GetLatestProjects():

public partial class GetLatestProjects_Result 
{ 
   public int ProjectID { get; set; } 
   public string Title { get; set; } 
   public string ShortDescr { get; set; } 
   public string Full_Descr { get; set; } 
   public int ProCatID { get; set; } 
   public bool Marquee { get; set; } 
}

without it i get error Cannot implicitly convert type 'System.Data.Objects.ObjectResult<Test.GetLatestProjects_Result>' to 'System.Linq.IQueryable<Test.Project> — Ayman Sharaf
– Ayman Sharaf, Commented Jul 15, 2014 at 9:58
Yes, but what does it return? Can you show the method outline? — DavidG
– DavidG, Commented Jul 15, 2014 at 10:06
@AymanSharaf: In future, please can you update the question directly instead of posting code samples in the comments. I have added them for you on this occasion. Thanks! — Dominic Zukiewicz
– Dominic Zukiewicz, Commented Jul 15, 2014 at 10:26

DavidG · Accepted Answer · 2014-07-15 10:35:07Z

1

Your stored procedure is returning ObjectResult<Test.GetLatestProjects_Result> and you are trying to convert it to IQueryable<Test.Project>. To do this you need to convert using the Linq Select method. Assuming Test.GetLatestProjects_Result and Test.Project have the same properties:

public IQueryable<Test.Project> ListView1_GetData()
{
    using (DREntities2 db=new DREntities2())
    {
        return db.GetLatestProjects().Select(p => new Test.Project
        {
            ProjectId = p.ProjectId,
            Title = p.Title,
            ShortDescr = p.ShortDescr,
            Full_Descr = p.Full_Descr,
            ProCatID = p.ProCatID,
            Marquee = p.Marquee
        }).AsQueryable();
    }
}

answered Jul 15, 2014 at 10:35

DavidG

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2 Comments

Ayman Sharaf Over a year ago

This solution worked fine. but i realised all i needed to do is to change the item type of el listview to the type of the stored procedure ItemType="Test.GetLatestProjects_Result

Diomedes Over a year ago

Ayman, could you please post what changes you did in code behind as well?

Hingst · Accepted Answer · 2015-12-29 05:11:43Z

A little late to the game, but others may be able to do the following. Assuming that Test.Project is an EntityType, in the Model Browser change the return type of your stored procedure in the EF Model to Test.Project instead of the default GetLatestProjects_Result "complex type" that is created.

Then, in your query you can take the result to a typed list, then call AsQueryable on the result.

Here is an example that calls an SP named GetAllRequestsByWorkflowState which returns TravelRequestSummaryView entities:

private IQueryable<TravelRequestSummaryView> GetApprovalRequests(int approvalState)
{
    IQueryable<TravelRequestSummaryView> trsv = null;
    try
    {
        var res = db.GetAllRequestsByWorkflowState(approvalState)
            .ToList<TravelRequestSummaryView>();
        trsv = res.AsQueryable();
    }
    catch (Exception ex)
    {
        sqlTraceManager.WriteTraceIf(ex, User.Identity.Name);
    }
    return trsv;
}

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