How to do a nested count with OData and LINQ?

Question

Here is the query I am trying to run from my OData source:

var query = from j in _auditService.AuditJobs.IncludeTotalCount()
   orderby j.Description
   select new 
      {
         JobId = j.ID,
         Description = j.Description,
         SubscriberCount = j.JobRuns.Count()
      };

It runs great if I don't use the j.JobRuns.Count(), but if I include it I get the following error:

Constructing or initializing instances of the type <>f__AnonymousType1`3[System.Int32,System.String,System.Int32] with the expression j.JobRuns.Count() is not supported.

It seems to be a problem of attempting to get the nested count through OData. What is a work around for this? I was trying to avoid getting the whole nested collection for each object just to get a count.

Thanks!

Answer 1

As of today the OData protocol doesn't support aggregates.

Projections yes, but projections that include aggregate properties no.

Alex

Answer 2

You need .Net 4.0 and In LinqPad you can run following over netflix OData Service

void Main()
{
    ShowPeopleWithAwards();
    ShowTitles();
}

// Define other methods and classes here
public void ShowPeopleWithAwards()
{
    var people = from p in People.Expand("Awards").AsEnumerable()
            where p.Awards.Count > 0
            orderby p.Name
            select new
            {
              p.Id,
                    p.Name,
              AwardCount = p.Awards.Count,
             TotalAwards = p.Awards.OrderBy (a => a.Type).Select (b => new { b.Type, b.Year} )
                 };

    people.Dump();
}

public void ShowTitles()
{
    var titles = from t in Titles.Expand("Awards").AsEnumerable()
            where t.ShortName != string.Empty && 
                  t.ShortSynopsis != string.Empty &&
             t.Awards.Count > 0
            select t;
    titles.Dump();
}