Question

I have a very strange issue that I cannot explain. I have my base mapping with this

//This will automatically cast the row into the correct object type based on the value in AccountType
DiscriminateSubClassesOnColumn<string>("AccountType")
            .Formula(String.Format("CASE AccountType WHEN {0} THEN '{1}' WHEN {2} THEN '{3}' ELSE '{4}' END", 
            (int)PaymentMethodType.CheckingAccount, 
            typeof(ACH).Name,
            (int)PaymentMethodType.SavingsAccount,
            typeof(ACH).Name,
            typeof(CreditCard).Name));

I have looked in the logs, I have executed the sql that nhibernate is generating, and all records have the same data. There is not difference in them that would denote why this should not work.

The base class is PaymentMethodBase. I have 2 subclasses, CreditCard and ACH, which inherit from PaymentMethodBase.

Then, I have this extension

public static string PaymentMethodName(this PaymentMethodBase paymentMethod)
{
        if (paymentMethod is ACH)
        {
            var ach = (ACH)paymentMethod;
            return String.Format("{0} {1}", ach.BankName, String.Format("XXXX{0}", ach.AccountNumber.Substring(ach.AccountNumber.Length - 4)));
        }

        if (paymentMethod is CreditCard)
        {
            var creditCard = (CreditCard)paymentMethod;
            return String.Format("{0} {1}", creditCard.Name, creditCard.CreditCardNumber);
        }

        return "Unknown Payment Method";
    }

Which I call like this.

public SelectList PaymentMethodsSelectList
{
    get
    {
        var methods = (from p in PaymentMethods
                       where p != null
                       select new
                       {
                           id = p.PaymentMethodId,
                           name = p.PaymentMethodName()
                       }).OrderBy(x => x.name);

        var results = methods.ToList();

        results.Insert(0, new { id = (int)NewPaymentMethods.ACH, name = "<New eCheck Account...>" });
        results.Insert(0, new { id = (int)NewPaymentMethods.CreditCard, name = "<New Credit Card...>" });

        return new SelectList(results, "id", "name");
    }
}

This code is used by 2 models. The collection of payment methods are all coming from the same object – a customer object. The collection is mapped like this.

HasMany<PaymentMethodBase>(x => x.PaymentMethods)
    .KeyColumn("CustomerId")
    .Where(y => y.AccountType < 10)
    .Inverse()
    .Cascade.All();

So, I get the customer 2 different ways. One is that I get the customer through another object (main site). The other has the object being pulled directly by id (in an iframe). The direct by id method works every time. The other method, where I get the customer through another object, causes only the first and last payment method to cast correctly. If there are more than 2, they are left in the base class and appear in the middle of the list after the sort.

I have tried changing the parent object to just mapping the id and then getting the customer record by the ID. Failure. There is something else in the way that is causing this to happen, but only on that one model.

Answer 1

I suspect that the issue here is Fetching issue.

Since the extension method is running on the .Net side rather than in the “NHibernate level” it cannot run properly when the collection of payment methods is not available.

Perhaps in the direct by Id methos you have Fetching set up for the payments whereas in the indirect method the automatic fetching goes only to the Customer object but stops short before fetching the Payment methods.

Try to instruct NHibernate to pre-fetch the Payment methods for you in the indirect method.

Something like:

Session.Query<SomeObject>.Where(.....).Fetch(x => x.Customer).ThenFetch(c => c.PaymentMethods)