Question

I’ve written a LINQ query that should return an int value. but I’m not able to convert this value to int and an exception occured:
Unable to cast object of type ‘QuickRoutes.DAL.RouteLinq’ to type ‘System.IConvertible’.
this is my LINQ :

var res = (from p in aspdb.RouteLinqs
                       orderby p.RouteId descending
                       select p).Take(1);

and the exception occures here:

 route.Id =Convert.ToInt32(res.FirstOrDefault());

how can I solve this problem?

Answer 1

that is because res.FirstOrDefault() returns a RouteLinqs type object, because you are using select p , you may select a field using select p.FieldName, where FieldName is the property you require for conversion, which is probably RouteId

You may want to query the particular field in your linq query.

var res = (from p in aspdb.RouteLinqs
                       orderby p.RouteId descending
                       select p.RouteId).Take(1); //p.RouteID or any field you want. 

Or with your current query, you may do:

 route.Id =Convert.ToInt32(res.FirstOrDefault().RouteID);