Repository navigation
EnableClassInterceptors does not take into account enum KeyFilter parameters in the constructor #56
Description
Describe the Bug
When using EnableClassInterceptors() and registering a class with WithAttributeFiltering(), parameters decorated with KeyFilter will not have their filter taken into account when trying to intercept the class
Steps to Reproduce
using Autofac;
using Autofac.Extras.DynamicProxy;
using Autofac.Features.AttributeFilters;
using Microsoft.VisualStudio.TestTools.UnitTesting;
namespace Pruebas
{
[TestClass]
public class TestClassWithKeyedAttributeConstructor
{
enum TestEnum { STRING_ONE }
public class ClassWithKeyedAttributeConstructor
{
private readonly string str;
public ClassWithKeyedAttributeConstructor([KeyFilter(TestEnum.STRING_ONE)] string str) => this.str = str;
public string GetStr() => str;
}
[TestMethod]
public void TestClassWithKeyedAttributeConstructorCannotBeIntercepted()
{
var builder = new ContainerBuilder();
builder.Register(c => "Hello").Keyed<string>(TestEnum.STRING_ONE);
builder.Register(c => "World");
//builder.RegisterType<ClassWithKeyedAttributeConstructor>().WithAttributeFiltering();
builder.RegisterType<ClassWithKeyedAttributeConstructor>().WithAttributeFiltering().EnableClassInterceptors();
var container = builder.Build();
using var scope = container.BeginLifetimeScope();
Assert.AreEqual("Hello", scope.Resolve<ClassWithKeyedAttributeConstructor>().GetStr());
}
}
}Expected Behavior
Exception with Stack Trace
Message:
Assert.AreEqual failed. Expected:<Hello>. Actual:<World>.
Stack Trace:
TestClassWithKeyedAttributeConstructor.TestClassWithKeyedAttributeConstructorCannotBeIntercepted() line 32
Dependency Versions
Autofac: 8.1.1
Autofac.Extras.DynamicProxy: 7.1.0
MSTest: 3.6.2
Additional Info
If we uncomment line 26 and comment line 27. The test will execute correctly.
Activity
tillig commentedon Nov 14, 2024
I just wanted to jump in and say that your issue here has been seen but it may be a bit before someone can jump in and do anything about it. We're dreadfully short on PRs coming in and there are only a couple of active maintainers, both of whom are doing this in their shrinking spare time. If you want this solved faster, we'd very much welcome a PR that includes the fix and a test to validate the fix.
My initial guess is that when the proxy is generated for the interceptor that we're not copying the attributes from the original class constructor parameters over to the interceptor constructor parameters. Is that right? Is there something else? I don't know without diving in and just solving the problem, which I don't have time for at this exact moment. But if you were going to try for a PR, that'd be a good place to start looking.
elgatov commentedon Nov 14, 2024
Hi tillig,
I understand this is a side project and time is tight. I will try to check what you are pointing me too and see if I can fix it and get a PR, but as of right now I feel it is above my knowledge of c#.
Thanks for the help
elgatov commentedon Nov 18, 2024
I believe the error is exactly in
Autofac.Extras.DynamicProxy/src/Autofac.Extras.DynamicProxy/RegistrationExtensions.cs
Line 130 in 2115f37
for each
PositionalParameterit is trying to resolve the service without taking into account if it's keyed. Tell me if you believe this is indeed the problem to pursue it further.Thank you.
tillig commentedon Nov 18, 2024
I think that's a reasonable place to start, for sure.
tillig commentedon Jun 24, 2026
After digging into this, the root cause is a bug in Castle DynamicProxy, not in this library or in Autofac core.
When
EnableClassInterceptorsgenerates the proxy subclass, Castle replicates the constructor parameter attributes onto the proxy's constructor.KeyFilterAttribute's constructor parameter is typedobject(KeyFilterAttribute(object key)), so an enum key gets boxed — and Castle reproduces that boxed enum argument as its underlying integer rather than the original enum type.The attribute is still present on the proxy constructor, but
KeyFilterAttribute.Keyends up as boxed(int)0instead ofTestEnum.STRING_ONE. Core'sWithAttributeFilteringthen looks upnew KeyedService((int)0, typeof(string)), which doesn't match the registeredKeyedService(TestEnum.STRING_ONE, typeof(string))— so the filter silently misses (picking an unkeyed fallback if one exists, or failing to bind the constructor if not).Key points:
objectlosslessly.EnableClassInterceptors.EnableInterfaceInterceptorsdoesn't rewrite the constructor, so the original attribute is read intact.I've filed an upstream issue with a minimal (Autofac-free) repro: castleproject/Core#748.
Workarounds until Castle fixes it:
[KeyFilter], orEnableInterfaceInterceptorsinstead ofEnableClassInterceptors.We'll track the upstream issue and revisit once Castle ships a fix.
[-]EnableClassInterceptors does not take into account KeyFilter-ed parameters in the constructor[/-][+]EnableClassInterceptors does not take into account enum KeyFilter parameters in the constructor[/+]Merge pull request #65 from autofac/feature/issue-56