Class MediatorServiceCollectionExtensions

Namespace

Microsoft.Extensions.DependencyInjection

Assembly

Stratara.Mediator.dll

DI extensions that register the Stratara mediator + pipeline behaviors + handler discovery.

public static class MediatorServiceCollectionExtensions

Inheritance

object

MediatorServiceCollectionExtensions

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Methods

AddCommandHandlersFromAssemblyContaining<T>(IServiceCollection)

Scan the assembly containing T and register every concrete ICommandHandler<TRequest> implementation as a scoped service.

public static IServiceCollection AddCommandHandlersFromAssemblyContaining<T>(this IServiceCollection services)

Parameters

services IServiceCollection

The service collection to mutate.

Returns

IServiceCollection

The same service collection, to enable chaining.

Type Parameters

T

A marker type from the assembly to scan. Typically Program or the application's marker interface.

Examples

Register every command handler in the host's assembly via a marker interface so domain assemblies are scanned without referencing concrete types here:

public interface IAppMarker { }

builder.Services.AddCommandHandlersFromAssemblyContaining<IAppMarker>();

AddMediator(IServiceCollection)

Register IMediator as a scoped service.

public static IServiceCollection AddMediator(this IServiceCollection services)

Parameters

services IServiceCollection

The service collection to mutate.

Returns

IServiceCollection

The same service collection, to enable chaining.

Examples

Register the mediator alongside handlers discovered in the host's assembly:

var builder = WebApplication.CreateBuilder(args);

builder.Services
    .AddMediator()
    .AddCommandHandlersFromAssemblyContaining<Program>()
    .AddQueryHandlersFromAssemblyContaining<Program>();

Remarks

Idempotent — calling multiple times appends duplicate registrations; DI resolves the last one. Use AddAuthorizingMediator<TAuthorizationProvider>(IServiceCollection) instead if you want the authorizing decorator chain.

Every dispatch is traced. A OpenTelemetry.Trace.Tracer the host has registered — before or after this call — is the one the mediator uses. Where the host registers none, a fallback is registered that emits the dispatch spans from the framework's own activity source, SourceName, so a host that subscribes to framework telemetry sees them and a host that subscribes to nothing pays for nothing. No telemetry registration is required for the mediator to start.

This method also wires a startup-time validator that fails fast if the host registers [RequireRole]-annotated request types without also pointing IMediator at an IAuthorizingMediator. Custom decorators that wrap Stratara.Mediator.Authorization.AuthorizingMediator must implement IAuthorizingMediator on their outermost layer so the validator recognises them.

AddPipelineBehavior(IServiceCollection, Type)

Register an open-generic IPipelineBehavior<TRequest> implementation for void commands.

public static IServiceCollection AddPipelineBehavior(this IServiceCollection services, Type openGenericBehaviorType)

Parameters

services IServiceCollection

The service collection to mutate.

openGenericBehaviorType Type

An open generic type definition with one type parameter.

Returns

IServiceCollection

The same service collection, to enable chaining.

Examples

Behaviours run in registration order, outermost first:

services.AddPipelineBehavior(typeof(LoggingBehavior<>));

Remarks

The provided type must be a one-parameter open generic (e.g. typeof(LoggingBehavior<>)). Behaviors are resolved per-request in DI registration order — first registered runs outermost. Registering the same behavior type more than once installs it once, so a host that composes overlapping service bundles does not run the behavior twice.

Exceptions

ArgumentNullException

openGenericBehaviorType is null.

ArgumentException

openGenericBehaviorType is not an open generic with one type parameter.

AddPipelineBehaviorWithResult(IServiceCollection, Type)

Register an open-generic IPipelineBehavior<TRequest, TResult> implementation.

public static IServiceCollection AddPipelineBehaviorWithResult(this IServiceCollection services, Type openGenericBehaviorType)

Parameters

services IServiceCollection

The service collection to mutate.

openGenericBehaviorType Type

An open generic type definition with two type parameters.

Returns

IServiceCollection

The same service collection, to enable chaining.

Examples

The result-returning request shape needs its own registration — a behaviour registered only through AddPipelineBehavior never sees a query:

services.AddPipelineBehaviorWithResult(typeof(LoggingBehavior<,>));

Remarks

The provided type must be a two-parameter open generic (e.g. typeof(LoggingBehavior<,>)). Behaviors are resolved per-request in DI registration order — first registered runs outermost. Registering the same behavior type more than once installs it once, so a host that composes overlapping service bundles does not run the behavior twice.

Exceptions

ArgumentNullException

openGenericBehaviorType is null.

ArgumentException

openGenericBehaviorType is not an open generic with two type parameters.

AddQueryHandlersFromAssemblyContaining<T>(IServiceCollection)

Scan the assembly containing T and register every concrete IQueryHandler<TRequest, TResult> implementation as a scoped service.

public static IServiceCollection AddQueryHandlersFromAssemblyContaining<T>(this IServiceCollection services)

Parameters

services IServiceCollection

The service collection to mutate.

Returns

IServiceCollection

The same service collection, to enable chaining.

Type Parameters

T

A marker type from the assembly to scan. Typically Program or the application's marker interface.

Examples

Register every query handler in the host's assembly. The same call also picks up handlers for ICommand<TResult> because both share the IQueryHandler<TRequest, TResult> contract.

builder.Services.AddQueryHandlersFromAssemblyContaining<IAppMarker>();