Adding related table fields to class via Entity Framework

Question

Every building has multiple rooms. I would like to return data from a building that includes a room number from every room owned by said building via a class buildingView, which looks like this right now (with some pseudocode):

public class buildingView
{
    public int id { get; set; }
    public string name { get; set; }
    ...
    public *something* roomNumbers *something*
}

To that end, I have the following query:

buildingView building = db.buildings.Select(b => new buildingView
{
    id = b.id,
    name = b.name,
    ...
    roomNumbers = *I have no idea*
})
.Where(b => b.id == id)
.SingleOrDefault();

Room numbers are all strings, if that's relevant.

My questions:

How can I get my list of room numbers?

How can I improve my question's title? I lack the vocabulary right now to do better.

Is there a another way entirely?

Thanks!

P.S. If you are going to downvote, please say why. Otherwise how will I know how to improve my questions?

Have a look at the accepted answer for Entity Framework: Querying Child Entities. Whereas they're looking based on age, you'd use whatever criteria you've defined to match the room to build (e.g. BuildingId). If you need more help please add your building and room classes to the question. — Tone
– Tone, Commented Jul 5, 2016 at 19:51
OP: How would you do it without Entity Framework? Write it that way and let EF figure out the rest. It's what EF is for. — Spivonious
– Spivonious, Commented Jul 5, 2016 at 19:59

Gert Arnold · Accepted Answer · 2016-07-05 20:03:58Z

1

Assuming you have a class like ...

class Building
{
    ...
    public ICollection<Room> Rooms { get; set; }
}

And that BuildingView is ...

public class BuildingView
{
    public int Id { get; set; }
    public string Name { get; set; }
    ...
    public IEnumerable<string> RoomNumbers { get; set; }
}

... you can get the concatenated room numbers as follows:

var buildingViews = context.Buildings
                           .Select(b => new BuildingView
                            {
                                Id = b.Id,
                                Nems = b.Name,
                                RoomNumbers = b.Rooms
                                               .Select(r => r.Number)
                            });

Side note: it's really recommended to use C# naming conventions, like PascalCase for class and property names.

edited Jul 5, 2016 at 20:03

answered Jul 5, 2016 at 19:54

Gert Arnold

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