SUM 2 columns nested objects in entity framework

Question

Here is how the model links: project can have multiple tasks, tasks can have multiple times books against it. tasktimes have got taskhours and employee on it Employee has a standardcost.

I am currently working out the sum of the costs of all tasks by looping each task and then multiply the 2 columns i need, and then i sum that.

public decimal CalculateCost(IEnumerable<Task> tasks)
{
    decimal total = 0.0M;

    foreach (var task in tasks)
    {
        var cost = from d in task.TaskTimes
               select new { total = d.Employee.StandardCost * d.TaskHours };

        total = cost.Sum(d => d.total);
    }           
    return total;
}

There must be a better way to do this rather than doing that foreach loop but I can't seem to find the syntax. Is there a more efficient approach or is this the way to do it?

Thanks :)

Answer 1

try using SelectMany()

var total = tasks.SelectMany(x => x.TaskTimes)
                 .Sum(d => d.Employee.StandardCost * d.TaskHours);