EntityFramework Sorting a subset - linq

Question

I have a list of messages. In each message, there are a list of response types. I need to pull the query in such a way that the messages are ordered by ID and the response types are also ordered by ID. They are NOT ordered by ID in the database.
messageResponse.Messages = (from m in db.Messages.Include("ResponseType")
.SomeMagicSubSortThing("ResponseType.ID")
select m).OrderBy(m1 => m1.ID).ToList<Message>();
This should result in:
Message ID Col1 Col2
-- ResponseType ID Col1 Col2
...like so:
1 MessageA MessageB
-- 1 ResponseTypeC ResponseTypeD
-- 2 ResponseTypeQ ResponseTypeR
-- 3 ResponseTypeX ResponseTypeZ
-- 4 ResponseTypeL ResponseTypeM
2 MessageE MessageF
-- 1 ResponseTypeG ResponseTypeH
-- 2 ResponseTypeI ResponseTypeJ
-- 3 ResponseTypeB ResponseTypeS
-- 4 ResponseTypeL ResponseTypeC
Right now, I can get the messages in order, but the response types are in whatever order the database has them. How can I sub-sort the response types?

Answer 1

I think what you are looking for is ThenBy():
messageResponse.Messages = (from m in db.Messages.Include("ResponseType")
.SomeMagicSubSortThing("ResponseType.ID")
select m).OrderBy(m1 => m1.ID).ThenBy(n=>n.ResponseType.ID).ToList<Message>()
UPDATE
In your entity can you simply define a calculated property like:
class Message {
public ICollection<Response> Responses {get; set;}
public ICollection<Response> SoretedResponses {
get { return this.Responses.OrderBy(n=>n.Response); }
}
}
Or am I still missing the issue?

Answer 2

EF doesn't do this nicely, but you do have two options:
1) Use a Select clause in your Linq to Entities query:
var messages = db.Messages
.OrderBy( o => o.ID )
.Select( o => new
{
Message = o,
ResponseTypes = o.ResponseTypes.OrderBy( x => x.ID ),
}
)
.ToList()
;
This is the only way to get EF to sort child properties on the database server.
Your output List will have elements of the anonymous type in the Select
2) Use Linq to Objects on the output List<Message> to sort the collections of ResponseType:
List<Message> messages = db.Messages
.Include( o => o.ResponseTypes )
.OrderBy( o => o.ID )
.ToList()
;
foreach( var message in messages )
{
message.ResponseTypes = message.ResponseTypes.OrderBy( x => x.ID ).ToList();
}
This gets all the records from the database and then sorts them in memory.
The output list will have elements of type Message with the navigation property populated.