LINQ Aggregates in Where string

Question

I am building a where-condition-string dynamically from user inputs to query on an ObjectSet.

So I've got something like:

// Filter name
whereConditions.Add("it.Name=@Name");
parameters.Add(new ObjectParameter("Name", model.Name));
// Filter Bonuspoints
whereConditions.Add("it.CustomerBonusPoint.BonusPoints=@BonusPoints");
parameters.Add(new ObjectParameter("BonusPoints", model.BonusPoints));
// Query
db.persons.Where(whereConditions, parameters.ToArray());

Which works perfectly even for related objects as you can see above.

But somehow I am not able to use aggregates. This doesn't work:

whereConditions.Add("it.CustomerSaleFigures.Sum(x=>x.Turnover)>@Turnover");
parameters.Add(new ObjectParameter("Turnover", model.Turnover));

Am I missing something? Any help appreciated!

Answer 1

The string conditions used by ObjectQuery are Entity SQL, not C# Linq.

whereConditions.Add(@"
    Sum(
      SELECT Turnover
      FROM NAVIGATE(it.CustomerSaleFigures)
    ) > @Turnover");

parameters.Add(new ObjectParameter("Turnover", model.Turnover));

(I'm not sure if NAVIGATE() is required)

Alternatively, you could use Linq:

IQueryable<Person> query = db.persons;
query = query.Where(c => c.Name == model.Name);
query = query.Where(c => c.CustomerBonusPoint.BonusPoints == model.BonusPoints);
query = query.Where(c => c.CustomerSaleFigures.Sum(sf => sf.Turnover) > model.Turnover);

return query.ToList();