MongoDB LinQ “Select” method will really retrieve only a subset of fields?

Question

Searching across the internet how to retrieve a subset of fields in MongoDB, using C# official driver (but using LinQ as the base architecture) I found how to do this in Mon

Answer 1

This is cheating... but:

//This actual implementation is untested and may contain small errors.
//The helper method has been tested and *should* work.

public static IMongoQuery GetMongoQuery(this IQueryable query)
{
    return ((MongoQueryable)query).GetMongoQuery();
}

var temp =
    from x in DB.Foo.AsQueryable()
    where x.SomeField > 5;
    select (x.OtherField);

return temp.GetMongoQuery().ToJson();