AdaskoTheBeAsT.MediatR.SimpleInjector and AdaskoTheBeAsT.MediatR.SimpleInjector.AspNetCore

MediatR extension to SimpleInjector

Programming language: C#

License: MIT License

Tags: Messaging     Dependency-injection     DI     Inversion-of-Control     IOC     Queue    

README

AdaskoTheBeAsT.MediatR.SimpleInjector and AdaskoTheBeAsT.MediatR.SimpleInjector.AspNetCore

MediatR extensions for SimpleInjector.

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Usage in AspNetCore

Scans assemblies and adds handlers, preprocessors, and postprocessors implementations to the SimpleInjector container. Additionaly it register decorator which passes HttpContext.RequestAborted cancellation token from asp.net core controllers to MediatR.
Install package AdaskoTheBeAsT.MediatR.SimpleInjector.AspNetCore.
There are few options to use with Container instance:

1. Marker type from assembly which will be scanned

   container.AddMediatRAspNetCore(typeof(MyHandler), type2 /*, ...*/);
   

2. Assembly which will be scanned

   container.AddMediatRAspNetCore(assembly, assembly2 /*, ...*/);
   

3. Full configuration

   var testMediator = new Mock<IMediator>();
   container.AddMediatR(
       cfg =>
       {
           cfg.Using(() => testMediator.Object);
           cfg.WithHandlerAssemblyMarkerTypes(typeof(MyMarkerType));
           cfg.UsingBuiltinPipelineProcessorBehaviors(true);
           cfg.UsingPipelineProcessorBehaviors(typeof(CustomPipelineBehavior<,>));
           cfg.UsingStreamPipelineBehaviors(typeof(CustomStreamPipelineBehavior<,>));
       });
   

Usage in other project types

Scans assemblies and adds handlers, preprocessors, and postprocessors implementations to the SimpleInjector container.
Install package AdaskoTheBeAsT.MediatR.SimpleInjector.
There are few options to use with Container instance:

1. Marker type from assembly which will be scanned

   container.AddMediatR(typeof(MyHandler), type2 /*, ...*/);
   

2. List of assemblies which will be scanned.

Below is sample for scanning assemblies from some solution.

```cs
[ExcludeFromCodeCoverage]
public static class MediatRConfigurator
{
    private const string NamespacePrefix = "YourNamespace";

    public static void Configure(Container container)
    {
        var loadedAssemblies = AppDomain.CurrentDomain.GetAssemblies().ToList();
        var assemblies = new List<Assembly>();
        var mainAssembly = typeof(MediatRConfigurator).GetTypeInfo().Assembly;
        var refAssemblies = mainAssembly.GetReferencedAssemblies();
        foreach (var assemblyName in refAssemblies
            .Where(a => a.FullName.StartsWith(NamespacePrefix, StringComparison.OrdinalIgnoreCase)))
            {
                var assembly = loadedAssemblies.Find(l => l.FullName == assemblyName.FullName)
                    ?? AppDomain.CurrentDomain.Load(assemblyName);
                assemblies.Add(assembly);
            }
        container.AddMediatR(assemblies);
    }
}
```

This will register:

• IMediator as Singleton
• IRequestHandler<> concrete implementations as Transient
• INotificationHandler<> concrete implementations as Transient
• IStreamRequestHandler<> concrete implementations as Transient

Advanced usage

Setting up custom IMediator instance and marker type from assembly for unit testing (Moq sample)

    var testMediator = new Mock<IMediator>();
    container.AddMediatR(
        cfg =>
        {
            cfg.Using(() => testMediator.Object);
            cfg.WithHandlerAssemblyMarkerTypes(typeof(MyMarkerType));
        });

Setting up custom IMediator implementation and marker type from assembly

    container.AddMediatR(
        cfg =>
        {
            cfg.Using<MyCustomMediator>();
            cfg.WithHandlerAssemblyMarkerTypes(typeof(MyMarkerType));
        });

Setting up custom IMediator implementation and assemblies to scan

    container.AddMediatR(
        cfg =>
        {
            cfg.Using<MyCustomMediator>();
            cfg.WithAssembliesToScan(assemblies);
        });

Setting assemblies to scan and different lifetime for IMediator implementation

    container.AddMediatR(
        cfg =>
        {
            cfg.WithAssembliesToScan(assemblies);
            cfg.AsScoped();
        });

Setting assemblies to scan and additonaly enabling all builtin behaviors and user defined processors/handlers

This will register following behaviors:

• RequestPreProcessorBehavior<,>
• RequestPostProcessorBehavior<,>
• RequestExceptionProcessorBehavior<,>
• RequestExceptionActionProcessorBehavior<,>

and all user defined implementation of processors and handlers:

• IRequestPreProcessor<>
• IRequestPostProcessor<,>
• IRequestExceptionHandler<,,>
• IRequestExceptionActionHandler<,>

    container.AddMediatR(
        cfg =>
        {
            cfg.WithAssembliesToScan(assemblies);
            cfg.UsingBuiltinPipelineProcessorBehaviors(true);
        });

Setting assemblies to scan and additonaly enabling choosen builtin behaviors and user defined processors/handlers

This will register following behaviors:

• RequestPreProcessorBehavior<,>
• RequestExceptionProcessorBehavior<,>

and all user defined implementation of processors and handlers:

• IRequestPreProcessor<>
• IRequestExceptionHandler<,,>

    container.AddMediatR(
        cfg =>
        {
            cfg.WithAssembliesToScan(assemblies);
            cfg.UsingBuiltinPipelineProcessorBehaviors(
                requestPreProcessorBehaviorEnabled: true,
                requestPostProcessorBehaviorEnabled: false,
                requestExceptionProcessorBehaviorEnabled: true,
                requestExceptionActionProcessorBehaviorEnabled: false);
        });

Setting assemblies to scan and additonaly custom stream request handlers behaviors

This will register following stream behaviors:

• CustomStreamPipelineBehavior<,>

    container.AddMediatR(
        cfg =>
        {
            cfg.WithAssembliesToScan(assemblies);
            cfg.UsingStreamPipelineBehaviors(typeof(CustomStreamPipelineBehavior<,>));
        });

Setting assemblies to scan and additonaly enabling choosen builtin behaviors and user defined processors/handlers also with custom Pipeline Process Behaviours

    container.AddMediatR(
        cfg =>
        {
            cfg.WithAssembliesToScan(assemblies);
            cfg.UsingBuiltinPipelineProcessorBehaviors(
                requestPreProcessorBehaviorEnabled: true,
                requestPostProcessorBehaviorEnabled: false,
                requestExceptionProcessorBehaviorEnabled: true,
                requestExceptionActionProcessorBehaviorEnabled: false);
            cfg.UsingPipelineProcessorBehaviors(typeof(CustomPipelineBehavior<,>));
        });

Thanks to

• Jimmy Boggard for MediatR
• Steven van Deursen for SimpleInjector
• Sebastian Kleinschmager for idea of automatic passing RequestAborted to MediatR
• Konrad Rudolph for idea of IsAssignableToGenericType

Code originates from MediatR.Extensions.Microsoft.DependencyInjection and was changed to work with SimpleInjector.