NDLRCOR011: Keyed Service Unknown Key¶

Cause¶

A constructor parameter uses [FromKeyedServices("key")] to resolve a keyed service, but no [Keyed("key")] registration was found in the compilation.

Rule Description¶

When using source generation with [assembly: GenerateTypeRegistry], Needlr validates that [FromKeyedServices("key")] parameters reference keys that are statically discoverable.

// ℹ️ NDLRCOR011: No registration found for key "unknown"
public class PaymentHandler(
    [FromKeyedServices("unknown")] IPaymentProcessor processor)
{
}

This is an informational diagnostic (not a warning or error) because:

Keys may be registered at runtime via IServiceCollectionPlugin
The analyzer only validates statically-discoverable [Keyed] registrations

How to Fix¶

Option 1: Add [Keyed] Attribute¶

Register the service with a matching key:

[Keyed("primary")]
public class StripeProcessor : IPaymentProcessor { }

// ✅ Now validated - "primary" key is discovered
public class PaymentHandler(
    [FromKeyedServices("primary")] IPaymentProcessor processor)
{
}

Option 2: Register via Plugin (Suppress Diagnostic)¶

If registering via plugin, suppress the diagnostic:

// Plugin registers keyed services at runtime
public class PaymentPlugin : IServiceCollectionPlugin
{
    public void Configure(ServiceCollectionPluginOptions options)
    {
        options.Services.AddKeyedSingleton<IPaymentProcessor, StripeProcessor>("primary");
    }
}

// Suppress because key is registered via plugin
#pragma warning disable NDLRCOR011
public class PaymentHandler(
    [FromKeyedServices("primary")] IPaymentProcessor processor)
#pragma warning restore NDLRCOR011
{
}

Option 3: Project-Wide Suppression¶

# .editorconfig
[*.cs]
dotnet_diagnostic.NDLRCOR011.severity = none

Validation Logic¶

The analyzer: 1. Collects all [Keyed("key")] attributes from classes in the compilation 2. Collects all [FromKeyedServices("key")] parameters 3. Reports diagnostic when a key is not found in discovered registrations

Keys registered via plugins cannot be validated at compile time.

When This Analyzer Activates¶

This analyzer only runs when: 1. [assembly: GenerateTypeRegistry] is present 2. A constructor parameter has [FromKeyedServices("key")] attribute 3. The parameter type is not a framework type (System., Microsoft.)

Severity Levels¶

Level	Meaning
`info` (default)	Informational hint in IDE
`warning`	Promote to build warning
`error`	Fail the build
`none`	Disable completely