CODEWITHSUNDEEP
c#entity-frameworklambda
JimS-CLT
JimS-CLT

Reputation: 675

EF query won't cast

I am using EF 4.x to populate an ASP.NET dropdown list. I first create a variable:

CPAS_EM.qryxrefVendorWorker wrkrs;

Then, I go to populate it:

        using (CPASEntities sds = new CPASEntities())
        {
            wrkrs = (qryxrefVendorWorker)
                (from w in sds.qryxrefVendorWorkers 
                 where w.VendorID == currVendorID && 
                 ((w.ExpiryDate == null) | (w.ExpiryDate >= currWorkDate)) 
                 select w);
            ddlWorker.DataSource = wrkrs;
            ddlWorker.DataValueField = wrkrs.WorkerID.ToString();
            ddlWorker.DataTextField = wrkrs.WorkerName;
            ddlWorker.DataBind();
        }

I'm getting an error on the "wrkrs = ..." statement indicating a casting error:

System.InvalidCastException was unhandled by user code
Message=Unable to cast object of type 'System.Data.Objects.ObjectQuery`1[CPAS_EM.qryxrefVendorWorker]' to type 'CPAS_EM.qryxrefVendorWorker'

Can anyone point me in the right direction here?

Upvotes: 0

Views: 84

Answers (3)

whastupduck
whastupduck

Reputation: 1166

You can try this:

List<sds.qryxrefVendorWorkers > lstWorkers = 
    (from w in sds.qryxrefVendorWorkers 
     where w.VendorID == currVendorID && 
     ((w.ExpiryDate == null) | (w.ExpiryDate >= currWorkDate)) 
     select w).ToList();


ddlWorker.DataSource = lstWorkers;
ddlWorker.DataValueField = "WorkerID";
ddlWorker.DataTextField = "WorkerName";
ddlWorker.DataBind();

This will return a set of qryxrefVendorWorkers. The casting failed because (in simple terms) you tried to cast a set of objects into a single object when you cast the query into a qryxrefVendorWorker

Upvotes: 0

Jeff S
Jeff S

Reputation: 7484

Why do you need the variable declared outside of the using scope? Can't you do:

   using (CPASEntities sds = new CPASEntities())
    {
        var wrkrs = (from w in sds.qryxrefVendorWorkers 
                     where w.VendorID == currVendorID 
                       && ((w.ExpiryDate == null) | (w.ExpiryDate >= currWorkDate)) 
                     select w).FirstOrDefault();
        ddlWorker.DataSource = wrkrs;
        ddlWorker.DataValueField = wrkrs.WorkerID.ToString();
        ddlWorker.DataTextField = wrkrs.WorkerName;
        ddlWorker.DataBind();
    }

and eliminate the declaration altogether?

Also, as user1908061 said, you also need the FirstOrDefault() to get just a single object instead of a collection.

Upvotes: 0

user1908061
user1908061

Reputation: 626

Your code

(from w in sds.qryxrefVendorWorkers 
where w.VendorID == currVendorID && ((w.ExpiryDate == null) | (w.ExpiryDate >= currWorkDate)) 
select w)

is actually a query, not a single object. You probably want to add FirstOrDefault() to just get a single element. Then there's also no cast necessary.

Upvotes: 4

Related Questions