Unable to return custom class from WCF Data Service
I am trying to return a custom class from my WCF data service. My custom class is:
[DataServiceKey("ID")]
public class Applist {
public int ID { get; set; }
public string Name { get; set; }
}
My data service looks like:
public static void 开发者_运维知识库InitializeService(IDataServiceConfiguration config)
{
config.RegisterKnownType(typeof(Applist));
config.SetEntitySetAccessRule("*", EntitySetRights.All);
config.SetServiceOperationAccessRule("GetApplications", ServiceOperationRights.AllRead);
}
[WebGet]
public IQueryable<Applist> GetApplications() {
var result = (from p in this.CurrentDataSource.Applications
orderby p.ApplicationName
group p by p.ApplicationName into g
select new Applist { ID = g.Min(p => p.id), Name = g.Key });
return result.AsQueryable();
}
However when I run the service, it gives me an error:
Request Error Request Error The server encountered an error processing the request.
The exception message is 'Unable to load metadata for return type
'System.Linq.IQueryable`1[ApplicationService.Applist]' of method
'System.Linq.IQueryable`1[ApplicationService.Applist] GetApplications()'
The same query runs perfectly fine in LINQPad.
Refer to the below blog. It explains this scenario and a possible solution in detail: http://samuelmueller.com/2009/11/working-with-projections-and-dtos-in-wcf-data-services/
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