Need help with LINQ query and ASP.NET MVC?

Question

My repository returns a list of Accounts.

Each account has a date and a MoneySpent decimal amount. So, I have my list of Accounts and in my controller I'm trying to process this list a little.

I want to have an object which contains the string name of all the months in my Account list and a Sum of all money spent for that month.

Here is what I have tried:

    [AcceptVerbs(HttpVerbs.Get)]
    public ActionResult Detail(int id)
    {
        var recentAccounts = accountRepository.GetAccountsSince(DateTime.Now.AddMonths(-6));

        var monthlyTotals = from a in recentAccounts
                           group a by a.DateAssigned.Month.ToString("MMM") into m
                           select new 
                           { 
                               Month = m.Key,
                               MonthSum = m.Sum(a => a.MoneySpent)
                           };


        return View();

    }

Does this seem like the right way to calculate monthlyTotals?

Also, I've been using strongly typed views with ViewModels for each view, so what type should I make monthlyTotals so I can add it as a field on my ViewModel and pass it to my View?

Answer 1

I would probably break out that logic into a service layer class holding business logic. Along with that, if the view is expecting a structure different than the model, you would transform your results in your service method returning a custom model type.

Answer 2

Looks right to me.

When I need to pass data like this to my view, I create a class for it. So your class would look like this:

public class MonthlyTotal
{
    public string Month { get; set; }
    public decimal MonthSum { get; set; }
}

and your SELECT clause would look like this:

select new MonthlyTotal                          
{                                
    Month = m.Key,                               
    MonthSum= m.Sum(a => a.AmountAssigned)
}

Answer 3

Using an anonymous type won't work since the view code won't know what properties it has. I suggest creating a view-only model in the Models directory.

public class MonthlySumModel
{
     public string Month { get; set; }
     public decimal Sum { get; set; }
}

Then create a new model value in the select statement:

select new MonthlySumModel
          {
              Month = m.Key,
              Sum = m.Sum(a => a.MoneySpent)
          };

You can then use this model as the type for the view.