Question

What would be an EF method syntax equivalent for the following TSQL query?

select istb.service_id, ss.service_desc, selected=1
from istb_services istb
inner join setup_services ss on istb.service_id=ss.service_id
where istb.istb_id=3
union
select ss.service_id, ss.service_desc, selected=0
from setup_services ss
where ss.service_id not in (select service_id from istb_services where istb_id=3)

I tried converting the not in part of the query like following:

var _existing = context.istb_services.Where(e => e.istb_id == IstbID);
var _others = context.setup_services.Except(_existing);

but it is generating compile-time error:

The best overloaded method match for ‘System.Data.Objects.ObjectQuery.Except(System.Data.Objects.ObjectQuery)’ has some invalid arguments

I understand I can’t pass different type of ObjectQuery to the .Except method but then what would be the alternative code?

Thanks,

Answer 1

Try the following:

var resultA = 
    from istb in istb_services 
    join ss in setup_services on istb.service_id equals ss.service_id
    where istb.istb_id == 3
    select new { istb.service_id, ss.service_desc, selected = true };

var resultB =            
    from ss in setup_services 
    where !istb_services.Any(istb => 
        istb.service_id == ss.service_id &&
        istb.istb_id == 3)
    select new { ss.service_id, ss.service_desc, selected = false };

var result = resultA.Union(resultB);

Anonymous type initializers having identical fields should be compiled to the same anonymous type, making the two sequences compatible for the Union operation.