EF single entity problem - linq

Question

I need to return a single instance of my viewmodel class from my repository in order to feed this into a strongly-typed view
In my repository, this works fine for a collection of viewmodel instances:
IEnumerable<PAWeb.Domain.Entities.Section> ISectionsRepository.GetSectionsByArea(int AreaId)
{
var _sections = from s in DataContext.Sections where s.AreaId == AreaId orderby s.Ordinal ascending select s;
return _sections.Select(x => new PAWeb.Domain.Entities.Section()
{
SectionId = x.SectionId,
Title = x.Title,
UrlTitle = x.UrlTitle,
NavTitle = x.NavTitle,
AreaId = x.AreaId,
Ordinal = x.Ordinal
}
);
}
But when I attempt to obtain a single entity, like this:
public PAWeb.Domain.Entities.Section GetSection(int SectionId)
{
var _section = from s in DataContext.Sections where s.SectionId == SectionId select s;
return _section.Select(x => new PAWeb.Domain.Entities.Section()
{
SectionId = x.SectionId,
Title = x.Title,
UrlTitle = x.UrlTitle,
NavTitle = x.NavTitle,
AreaId = x.AreaId,
Ordinal = x.Ordinal
}
);
}
I get
Error 1 Cannot implicitly convert type
'System.Linq.IQueryable<PAWeb.Domain.Entities.Section>' to
'PAWeb.Domain.Entities.Section'. An explicit conversion exists
(are you missing a cast?)"
This has got to be simple, but I'm new to c#, and I can't figure out the casting. I tried (PAWeb.Domain.Entities.Section) in various places, but no success. Can anyone help??

Answer 1

Your query is returning an IQueryable, which could have several items. For example, think of the difference between an Array or List of objects and a single object. It doesn't know how to convert the List to a single object, which one should it take? The first? The last?
You need to tell it specifically to only take one item.
e.g.
public PAWeb.Domain.Entities.Section GetSection(int SectionId)
{
var _section = from s in DataContext.Sections where s.SectionId == SectionId select s;
return _section.Select(x => new PAWeb.Domain.Entities.Section()
{
SectionId = x.SectionId,
Title = x.Title,
UrlTitle = x.UrlTitle,
NavTitle = x.NavTitle,
AreaId = x.AreaId,
Ordinal = x.Ordinal
}
).FirstOrDefault();
}
This will either return the first item, or null if there are no items that match your query. In your case that won't happen unless the table is empty since you don't have a where clause.