nullable foreign key - bug in IQ driver

peterboncz

tested on MySQL with the IQ driver (latest versions of driver and linqpad).

use a database model with a nullable foreign key (say talbe "Event" with nullable foreign key column "AssistFrom").

try to delete using Linq a row "e" where this foreign key is NULL.

Events.DeleteOnSubmit(e);
submitChanges();

you get the exception in SubmitChanges():

InnerException: InvalidOperationException
The binary operator Equal is not defined for the types 'System.Int32' and 'System.Object'
at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor)
at System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, Object[] parameters, Object[] arguments)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at System.Reflection.RuntimePropertyInfo.GetValue(Object obj, BindingFlags invokeAttr, Binder binder, Object[] index, CultureInfo culture)
at System.Reflection.RuntimePropertyInfo.GetValue(Object obj, Object[] index)
at IQToolkit.ReflectionExtensions.GetValue(MemberInfo member, Object instance)
at IQToolkit.Data.Common.BasicMapping.d__13.MoveNext()
at IQToolkit.Data.EntitySession.d__15.MoveNext()
at System.Linq.Enumerable.d__81`1.MoveNext()
at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
at IQToolkit.Data.EntitySession.GetOrderedItems()
at IQToolkit.Data.EntitySession.b__0()
at IQToolkit.Data.DbEntityProvider.DoTransacted(Action action)
at IQToolkit.Data.EntitySession.SubmitChanges()
at IQDriver.IQContextBase.SubmitChanges()


This exception is avoided if one does thefollowing simple hack:

e.AssistFrom = 42; // hack, changing NULL into something non-null
Events.DeleteOnSubmit(e);
submitChanges();

// the exception does not trigger, everything executes happily

seems like a bug, somewhere in the IQ driver..


thanks in advance for helping solve this problem. My students, who I try to convince that LinQ is beautiful, hit this problem working on their assignment.. bad publicity for Linq.

thanks in advance for any help or fix,

Peter Boncz

BandiG

This is frustrating...
Especially since the workaround is not that simple when the operation is update and not delete.

Another stacktrace (I've tried to update a set of query results):
at System.RuntimeMethodHandle._InvokeMethodFast(IRuntimeMethodInfo method, Object target, Object[] arguments, SignatureStruct& sig, MethodAttributes methodAttributes, RuntimeType typeOwner)
at System.RuntimeMethodHandle.InvokeMethodFast(IRuntimeMethodInfo method, Object target, Object[] arguments, Signature sig, MethodAttributes methodAttributes, RuntimeType typeOwner)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, Boolean skipVisibilityChecks)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at System.Reflection.RuntimePropertyInfo.GetValue(Object obj, BindingFlags invokeAttr, Binder binder, Object[] index, CultureInfo culture)
at System.Reflection.RuntimePropertyInfo.GetValue(Object obj, Object[] index)
at IQToolkit.ReflectionExtensions.GetValue(MemberInfo member, Object instance)
at IQToolkit.Data.Common.BasicMapping.d__13.MoveNext()
at IQToolkit.Data.EntitySession.d__15.MoveNext()
at System.Linq.Enumerable.d__81`1.MoveNext()
at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
at IQToolkit.Data.EntitySession.GetOrderedItems()
at IQToolkit.Data.EntitySession.b__0()
at IQToolkit.Data.DbEntityProvider.DoTransacted(Action action)
at IQToolkit.Data.EntitySession.SubmitChanges()
at IQDriver.IQContextBase.SubmitChanges()

nkahoang

This is also bummer to me! Joe, can you have some comment on this matter, please?