Initializers, entity members, and entity navigation properties are the only things that work.

entity-framework linq

Question

I'm getting this exception :

The specified type member 'Paid' is not supported in LINQ to Entities. Only initializers, entity members, and entity navigation properties are supported.

    public ActionResult Index()
    {
        var debts = storeDB.Orders
            .Where(o => o.Paid == false)
            .OrderByDescending(o => o.DateCreated);

        return View(debts);
    }

My Model class

public partial class Order
{
    public bool Paid {
        get {
            return TotalPaid >= Total;
        }
    }

    public decimal TotalPaid {
        get {
            return Payments.Sum(p => p.Amount);
        }
    }

Payments is a Related table containing the field amount, The query works if I remove the Where clause showing correct information about the payments, any clue what's wrong with the code?

Solved like the answer suggested with :

    public ActionResult Index()
    {
        var debts = storeDB.Orders
            .OrderByDescending(o => o.DateCreated)
            .ToList()
            .Where(o => o.Paid == false);

        return View(debts);
    }
1
100
3/15/2016 12:51:13 PM

Accepted Answer

Entity is trying to convert your Paid property to SQL and can't because it's not part of the table schema.

What you can do is let Entity query the table with no Paid filter and then filter out the not Paid ones.

public ActionResult Index()
{
    var debts = storeDB.Orders
        //.Where(o => o.Paid == false)
        .OrderByDescending(o => o.DateCreated);

    debts = debts.Where(o => o.Paid == false);

    return View(debts);
}

That, of course, would mean that you bringing all of the data back to the web server and filtering the data on it. If you want to filter on the DB server, you can create a Calculated Column on the table or use a Stored Procedure.

112
10/21/2012 5:04:57 PM

Popular Answer

Just had to solve a similar problem. Solutions above require in-memory processing, which is a bad practice (lazy loading).

My solution was to write a helper that returned a predicate:

public static class Extensions
{
    public static Expression<Func<Order, bool>> IsPaid()
    {
        return order => order.Payments.Sum(p => p.Amount) >= order.Total;
    }
}

You can rewrite your linq statement as:

var debts = storeDB.Orders
                    .Where(Extensions.IsPaid())
                    .OrderByDescending(o => o.DateCreated);

This is handy when you want to reuse the calculation logic (DRY). Downside is that the logic is not in your domain model.



Related Questions





Related

Licensed under: CC-BY-SA with attribution
Not affiliated with Stack Overflow
Licensed under: CC-BY-SA with attribution
Not affiliated with Stack Overflow