KeyedService.AnyKey is not usable with ServiceKeyAttribute on `object`-typed arguments due to type validation

[DillonN]

Description

I'm trying to use the new Keyed services feature, but it looks like the KeyedService.AnyKey piece is not functional when used in conjunction with ServiceKeyAttribute?

E: Issue only occurs when trying to use a base class for the ServiceKeyAttribute argument, e.g. in the case below where object is the argument.

Whenever I try, all combination of types leads to an exception:

System.InvalidOperationException: 'The type of the key used for lookup doesn't match the type in the constructor parameter with the ServiceKey attribute.'

This appears to be due to a check that requires the parameter's type to be the same as the one on the registration:

runtime/src/libraries/Microsoft.Extensions.DependencyInjection/src/ServiceLookup/CallSiteFactory.cs

Lines 580 to 583 in 0b25e38

	if (parameterType != serviceIdentifier.ServiceKey.GetType())
	{
	throw new InvalidOperationException(SR.InvalidServiceKeyType);
	}

However, this is impossible because KeyedService.AnyKey uses a dedicated private type and is only exposed as object.

I feel like I'm missing something here, but how does KeyedService.AnyKey work with that strict type check in place?

Reproduction Steps

Create a new console app under .NET 8 RC2, add the Microsoft.Extensions.DependencyInjection package, and paste this into Program.cs:

using Microsoft.Extensions.DependencyInjection;

var services = new ServiceCollection();
services.AddKeyedTransient<Service>(KeyedService.AnyKey);

// This line throws
// System.InvalidOperationException: 'The type of the key used for lookup doesn't match the type in the constructor parameter with the ServiceKey attribute.'
using var provider = services.BuildServiceProvider(new ServiceProviderOptions { ValidateOnBuild = true });

// If ValidateOnBuild is false, this line also throws
// System.InvalidOperationException: 'The type of the key used for lookup doesn't match the type in the constructor parameter with the ServiceKey attribute.'
var service = provider.GetKeyedService<Service>("test");

public class Service
{
    public Service([ServiceKey] object serviceKey)
    { }
}

Expected behavior

• When using KeyedService.AnyKey for a service that uses the [ServiceKey] attribute, building the service provider should succeed without validation failures
• When using KeyedService.AnyKey for a service that uses the [ServiceKey] attribute, resolving the service using any key input should return the registered implementation and fill in the service key value for the marked parameter

Actual behavior

In both of the above points, a System.InvalidOperationException is thrown instead

Regression?

No response

Known Workarounds

I can workaround by using a factory service registration instead:

using Microsoft.Extensions.DependencyInjection;

var services = new ServiceCollection();
services.AddKeyedTransient<Service>(KeyedService.AnyKey, (_, key) => new Service(key));

// Validation succeeds now
using var provider = services.BuildServiceProvider(new ServiceProviderOptions { ValidateOnBuild = true });

// Resolving service also succeeds now
var service = provider.GetKeyedService<Service>("test");

public class Service
{
    public Service(object serviceKey)
    { }
}

Configuration

.NET SDK:
 Version:   8.0.100-rc.2.23502.2
 Commit:    0abacfc2b6

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.23550
 OS Platform: Windows
 RID:         win-x64
 Base Path:   C:\Program Files\dotnet\sdk\8.0.100-rc.2.23502.2\

.NET workloads installed:
<removed for brevity>

Host:
  Version:      8.0.0-rc.2.23479.6
  Architecture: x64
  Commit:       0b25e38ad3

.NET SDKs installed:
  8.0.100-rc.2.23502.2 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
<removed for brevity>
  Microsoft.NETCore.App 8.0.0-rc.2.23479.6 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
<removed for brevity>

Other architectures found:
  x86   [C:\Program Files (x86)\dotnet]
    registered at [HKLM\SOFTWARE\dotnet\Setup\InstalledVersions\x86\InstallLocation]

Environment variables:
  Not set

global.json file:
  Not found

Learn more:
  https://aka.ms/dotnet/info

Download .NET:
  https://aka.ms/dotnet/download

Other information

No response

Tagging subscribers to this area: @dotnet/area-extensions-dependencyinjection
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Description

I'm trying to use the new Keyed services feature, but it looks like the KeyedService.AnyKey piece is not functional when used in conjunction with ServiceKeyAttribute?

Whenever I try, all combination of types leads to an exception:

System.InvalidOperationException: 'The type of the key used for lookup doesn't match the type in the constructor parameter with the ServiceKey attribute.'

This appears to be due to a check that requires the parameter's type to be the same as the one on the registration:

runtime/src/libraries/Microsoft.Extensions.DependencyInjection/src/ServiceLookup/CallSiteFactory.cs

Line 580 in 0b25e38

if (parameterType != serviceIdentifier.ServiceKey.GetType())

However, this is impossible because KeyedService.AnyKey uses a dedicated private type and is only exposed as object.

I feel like I'm missing something here, but how does KeyedService.AnyKey work with that strict type check in place?

Reproduction Steps

Create a new console app under .NET 8 RC2, add the Microsoft.Extensions.DependencyInjection package, and paste this into Program.cs:

using Microsoft.Extensions.DependencyInjection;

var services = new ServiceCollection();
services.AddKeyedTransient<Service>(KeyedService.AnyKey);

// This line throws
// System.InvalidOperationException: 'The type of the key used for lookup doesn't match the type in the constructor parameter with the ServiceKey attribute.'
using var provider = services.BuildServiceProvider(new ServiceProviderOptions { ValidateOnBuild = true });

// If ValidateOnBuild is false, this line also throws
// System.InvalidOperationException: 'The type of the key used for lookup doesn't match the type in the constructor parameter with the ServiceKey attribute.'
var service = provider.GetKeyedService<Service>("test");

public class Service
{
    public Service([ServiceKey] object serviceKey)
    { }
}

Expected behavior

• When using KeyedService.AnyKey for a service that uses the [ServiceKey] attribute, building the service provider should succeed without validation failures
• When using KeyedService.AnyKey for a service that uses the [ServiceKey] attribute, resolving the service using any key input should return the registered implementation and fill in the service key value for the marked parameter

Actual behavior

In both of the above points, a System.InvalidOperationException is thrown instead

Regression?

No response

Known Workarounds

I can workaround by using a factory service registration instead:

using Microsoft.Extensions.DependencyInjection;

var services = new ServiceCollection();
services.AddKeyedTransient<Service>(KeyedService.AnyKey, (_, key) => new Service(key));

// Validation succeeds now
using var provider = services.BuildServiceProvider(new ServiceProviderOptions { ValidateOnBuild = true });

// Resolving service also succeeds now
var service = provider.GetKeyedService<Service>("test");

public class Service
{
    public Service(object serviceKey)
    { }
}

Configuration

.NET SDK:
 Version:   8.0.100-rc.2.23502.2
 Commit:    0abacfc2b6

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.23550
 OS Platform: Windows
 RID:         win-x64
 Base Path:   C:\Program Files\dotnet\sdk\8.0.100-rc.2.23502.2\

.NET workloads installed:
<removed for brevity>

Host:
  Version:      8.0.0-rc.2.23479.6
  Architecture: x64
  Commit:       0b25e38ad3

.NET SDKs installed:
  8.0.100-rc.2.23502.2 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
<removed for brevity>
  Microsoft.NETCore.App 8.0.0-rc.2.23479.6 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
<removed for brevity>

Other architectures found:
  x86   [C:\Program Files (x86)\dotnet]
    registered at [HKLM\SOFTWARE\dotnet\Setup\InstalledVersions\x86\InstallLocation]

Environment variables:
  Not set

global.json file:
  Not found

Learn more:
  https://aka.ms/dotnet/info

Download .NET:
  https://aka.ms/dotnet/download

Other information

No response

Author:	DillonN
Assignees:	-
Labels:	untriaged, area-Extensions-DependencyInjection
Milestone:	-

[steveharter]

PTAL @benjaminpetit

[benjaminpetit]

provider.GetKeyedService<Service>("test"); will not throw if you change the type of the key in your constructor to string instead of object. The type check might be a bit too restrictive here...

For services.BuildServiceProvider(new ServiceProviderOptions { ValidateOnBuild = true });, it seems to be a bug yes, I will investigate.

[DillonN]

@benjaminpetit thanks, I didn't notice that, was too focused with having object for the key type. I guess with the current check, doing that does not make sense? As the only thing I can get to work is provider.GetKeyedService<Service>(new object());. Any type that is not exactly System.Object will fail.

[benjaminpetit]

Yes, the type check is strict: if you are asking for an object in your constructor, the key provided must be an object. If you are asking for a string, then only a string can be provided. But we could allow inheritance IMO (your example could work for example).

[steveharter]

@benjaminpetit based on

provider.GetKeyedService("test"); will not throw if you change the type of the key in your constructor to string instead of object. The type check might be a bit too restrictive here...

For services.BuildServiceProvider(new ServiceProviderOptions { ValidateOnBuild = true });, it seems to be a bug yes, I will investigate.

and then later

Yes, the type check is strict: if you are asking for an object in your constructor, the key provided must be an object. If you are asking for a string, then only a string can be provided. But we could allow inheritance IMO (your example could work for example).

I assume the type check is strict by design, but we could loosen it up by supporting inheritance?