Using Multiple Group Functions in IQueryable <T>

Question

Given the following simple object

public class Foo {
    public int PrimaryKey;
    public int ForeignKey;
    public bool FlagOne;
    public bool FlagTwo;
}

Suppose I got it IQueryable<Foo>. Typically, if I want to perform a count operation for each flag, I would do the following:

IQueryable<Foo> foos = GetFoos();
var total = foos.Count();
var flagOneTotal = foos.Count(p => p.FlagOne);
var flagTwoTotal = foos.Count(p => p.FlagTwo);

In EF, the above would execute 3 queries in the database. I would like to get all this in one request.

For grouping, I can do this to execute a single request:

var q = from foo in foos
        group foo by foo.ForeignKey into g
        select new {
           ForeignKey = g.Key,
           Total = g.Count(),
           FlagOneTotal = g.Count(p => p.FlagOne),
           FlagTwoTotal = g.Count(p => p.FlagTwo)
        };

var list = q.ToList();

But how would I do the same if I want to get the totals for all the elements, regardless of the foreign key in one request, and one anonymous object?

In other words, as I would say .net, that all elements in foosshould be considered by 1 group, so I can perform Count operations on them.

Answer 1

:

var q = from foo in foos
        group foo by 1 into g
        select new {
           Total = g.Count(),
           FlagOneTotal = g.Count(p => p.FlagOne),
           FlagTwoTotal = g.Count(p => p.FlagTwo)
        };

var list = q.ToList();