Cannot be converted to type error when trying to use global filter with interface

[sw-ch]

I tried to setup a global filter to implement soft delete filtering accross all my entity types in the progress of migrating a project to NET Core.

Used versions:
Microsoft.EntityFrameworkCore 1.0.1
Z.EntityFramework.Plus.EFCore 1.4.9

The entity inheritance tree looks like this:
Interface: IEntityBase -> Abstract class: EntityBase -> Entity classes: Address, Offers...

When I try to initialize a global filter:
QueryFilterManager.Filter<IEntityBase>("IsActive", pe => pe.Where(e => e.State == null)); QueryFilterManager.InitilizeGlobalFilter(ctx);

I get the following error:

`System.ArgumentException was unhandled
HResult=-2147024809
Message=Object of type 'Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryable'1[Tst.IEntityBase]' cannot be converted to type 'Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryable'1[Test.Entities.Address]'.
Source=System.Private.CoreLib
StackTrace:
at System.RuntimeType.TryChangeType(Object value, Binder binder, CultureInfo culture, Boolean needsSpecialCast)
at System.RuntimeType.CheckValue(Object value, Binder binder, CultureInfo culture, BindingFlags invokeAttr)
at System.Reflection.MethodBase.CheckArguments(Object[] parameters, Binder binder, BindingFlags invokeAttr, CultureInfo culture, Signature sig)
at System.Reflection.RuntimeMethodInfo.InvokeArgumentsCheck(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at System.Reflection.RuntimePropertyInfo.SetValue(Object obj, Object value, Object[] index)
at Z.EntityFramework.Plus.QueryFilterSet.UpdateInternalQuery(DbContext context, Object query)
at Z.EntityFramework.Plus.QueryFilterQueryable'1.UpdateInternalQuery()
at Z.EntityFramework.Plus.QueryFilterContext.EnableFilter(BaseQueryFilter filter, Type[] types)
at Z.EntityFramework.Plus.QueryFilterManager.InitilizeGlobalFilter(DbContext context)

[zzzprojects]

Hello @sw-ch ,

Unfortunately, this is a documented limitation for EF Core: EF+ Query Filter - Limitations

This issue is due because EF Core cannot handle all casting scenario: dotnet/efcore#3736

By example

var sum1 = context.Inheritance_Interface_Entities
    .Cast<Inheritance_Interface_Entity>()
    .Sum(x => x.ColumnInt); // Aggregate, Max, Min, Sum

var sum2 = context.Inheritance_Interface_Entities
    .Cast<Inheritance_Interface_IEntity>()
    .Sum(x => x.ColumnInt); // Aggregate, Max, Min, Sum

var sum3 = context.Inheritance_Interface_Entities
    .Cast<Inheritance_Interface_IEntity>()
    .Cast<Inheritance_Interface_Entity>()
    .Sum(x => x.ColumnInt); // Aggregate, Max, Min, Sum

all throws exceptions since (Aggregate, Max, Min, Sum) is not handled correctly when a cast is used.

I will take one hour or two today to see if I can use a workaround since the fix has been reported multiple times (to milestone 7.00 -> 1.00 -> 1.01 -> 1.1.0-preview1 -> 1.2.0) by the EF Team.

Best Regards,

Jonathan

[sw-ch]

Hi Jonathan

Thanks for your quick reply. Sorry for bothering, should have seen that in the documentation.

Regards
Stephan

[zzzprojects]

Hello Stephan ,

Don't be sorry for that. It's always good to have a reminder from time to time to check if Cast method has been fixed or not.

A 'ForceCast' option has been added which may or not help you with this issue.

QueryFilterManager.ForceCast = true;

When enabled, Inherited class will now work and you will not longer get this error. However, some LINQ method will not longer work with Filtered query:

• Aggregate
• Max
• Min
• Sum

Let me know if that can partially fix your situation for now.

Best Regards,

Jonathan

[sw-ch]

Hi Jonathan

Thanks for the new version. Currently, I should be able to work around the limitations. It also seems to work with single table-per-hierarchy inheritance entities. I will need some time to figure out how much ground I can cover without hitting another wall...

Should I close the issue for now or do you want to keep it open as a reminder?

Regards
Stephan

[zzzprojects]

Hello @sw-ch ,

Let close it, that will make it easier to track other issues.

Best Regards,

Jonathan