Added IRequestFilter with Behaviour and IResultFilter with Behaviour (#4

)

* Added IRequestFilter with Behaviour to filter request of query or command.
* Added IResultFilter with Behaviour to filter result of query or command.

Cross.CQRS/Behaviors/EventQueueProcessBehavior.cs

@@ -1,6 +1,7 @@
 namespace Cross.CQRS.Behaviors;
 
-internal sealed class EventQueueProcessBehavior<T, TR> : IPipelineBehavior<T, TR> where T : IRequest<TR>
+internal sealed class EventQueueProcessBehavior<TRequest, TResult> : IPipelineBehavior<TRequest, TResult>
+    where TRequest : IRequest<TResult>
 {
     private readonly IEventQueueReader _eventReader;
     private readonly IMediator _mediator;
@@ -12,11 +13,11 @@ public EventQueueProcessBehavior(IEventQueueReader eventReader, IMediator mediat
     }
 
     /// <inheritdoc />
-    public async Task<TR> Handle(T request, RequestHandlerDelegate<TR> next, CancellationToken cancellationToken)
+    public async Task<TResult> Handle(TRequest request, RequestHandlerDelegate<TResult> next, CancellationToken cancellationToken)
     {
         var result = await next();
 
-        if (request is ICommand<TR> identifiable)
+        if (request is ICommand<TResult> identifiable)
         {
             var events = _eventReader.Read(identifiable.CommandId);
             foreach (var @event in events)

Cross.CQRS/Behaviors/RequestFilterBehavior.cs

@@ -0,0 +1,30 @@
+namespace Cross.CQRS.Behaviors;
+
+internal sealed class RequestFilterBehavior<TRequest, TResult> : IPipelineBehavior<TRequest, TResult>
+    where TRequest : IRequest<TResult>
+{
+    private readonly IEnumerable<IRequestFilter<TRequest>> _filters;
+
+    public RequestFilterBehavior(IEnumerable<IRequestFilter<TRequest>> filters)
+    {
+        _filters = filters;
+    }
+
+    /// <inheritdoc />
+    public async Task<TResult> Handle(TRequest request, RequestHandlerDelegate<TResult> next, CancellationToken cancellationToken)
+    {
+        var filters = _filters.ToArray();
+        if (filters.Length <= 0)
+        {
+            return await next();
+        }
+
+        var result = request;
+        foreach (var filter in filters)
+        {
+            result = await filter.ApplyFilterAsync(result, cancellationToken);
+        }
+
+        return await next();
+    }
+}

Cross.CQRS/Behaviors/ResultFilterBehavior.cs

@@ -0,0 +1,32 @@
+namespace Cross.CQRS.Behaviors;
+
+internal sealed class ResultFilterBehavior<TRequest, TResult> : IPipelineBehavior<TRequest, TResult>
+    where TRequest : IRequest<TResult>
+{
+    private readonly IEnumerable<IResultFilter<TRequest, TResult>> _filters;
+
+    public ResultFilterBehavior(IEnumerable<IResultFilter<TRequest, TResult>> filters)
+    {
+        _filters = filters;
+    }
+
+    /// <inheritdoc />
+    public async Task<TResult> Handle(TRequest request, RequestHandlerDelegate<TResult> next, CancellationToken cancellationToken)
+    {
+        var filters = _filters.ToArray();
+        if (filters.Length <= 0)
+        {
+            return await next();
+        }
+
+        var responce = await next();
+
+        var result = responce;
+        foreach (var filter in filters)
+        {
+            result = await filter.ApplyFilterAsync(result, cancellationToken);
+        }
+
+        return result;
+    }
+}

Cross.CQRS/Cross.CQRS.csproj

@@ -25,6 +25,8 @@
     <PackageReference Include="Microsoft.Extensions.Configuration" Version="8.0.0" />
 
     <PackageReference Include="Microsoft.CSharp" Version="4.7.0" />
+
+    <PackageReference Include="Scrutor" Version="4.2.2" />
   </ItemGroup>
 
 </Project>

Cross.CQRS/Filters/IRequestFilter.cs

@@ -0,0 +1,26 @@
+namespace Cross.CQRS.Filters;
+
+/// <summary>
+/// Defines a filter for a particular type.
+/// </summary>
+/// <remarks>
+///     Use it if you need to perform filter operation on the <see cref="TRequest"/>,
+///     after the query <see cref="IQuery{TResponse}"/> or command <see cref="ICommand"/>.
+/// </remarks>
+public interface IRequestFilter<TRequest>
+{
+    /// <summary>
+    /// Filter the specified instance.
+    /// </summary>
+    /// <param name="result">The instance to filter</param>
+    /// <returns>A ValidationResult object containing any validation failures.</returns>
+    TRequest ApplyFilter(TRequest result);
+
+    /// <summary>
+    /// Filter the specified instance asynchronously.
+    /// </summary>
+    /// <param name="result">The instance to filter</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>A ValidationResult object containing any validation failures.</returns>
+    Task<TRequest> ApplyFilterAsync(TRequest result, CancellationToken cancellationToken);
+}

Cross.CQRS/Filters/IResultFilter.cs

@@ -0,0 +1,26 @@
+namespace Cross.CQRS.Filters;
+
+/// <summary>
+/// Defines a filter for a particular type.
+/// </summary>
+/// <remarks>
+///     Use it if you need to perform filter operation on the <see cref="TResult"/>,
+///     after the query <see cref="IQuery{TResponse}"/> or command <see cref="ICommand"/>.
+/// </remarks>
+public interface IResultFilter<TRequest, TResult>
+{
+	/// <summary>
+	/// Filter the specified instance.
+	/// </summary>
+	/// <param name="result">The instance to filter</param>
+	/// <returns>A ValidationResult object containing any validation failures.</returns>
+	TResult ApplyFilter(TResult result);
+
+	/// <summary>
+	/// Filter the specified instance asynchronously.
+	/// </summary>
+	/// <param name="result">The instance to filter</param>
+	/// <param name="cancellationToken">Cancellation token</param>
+	/// <returns>A ValidationResult object containing any validation failures.</returns>
+	Task<TResult> ApplyFilterAsync(TResult result, CancellationToken cancellationToken);
+}

Cross.CQRS/Filters/RequestFilter.cs

@@ -0,0 +1,15 @@
+namespace Cross.CQRS.Filters;
+
+/// <summary>
+/// Base query/command filter.
+/// </summary>
+public abstract class RequestFilter<TRequest, TResult> : IRequestFilter<TRequest>
+    where TRequest : IRequest<TResult>
+{
+    /// <inheritdoc />
+    public TRequest ApplyFilter(TRequest request)
+        => ApplyFilterAsync(request, CancellationToken.None).GetAwaiter().GetResult();
+
+    /// <inheritdoc />
+    public abstract Task<TRequest> ApplyFilterAsync(TRequest request, CancellationToken cancellationToken);
+}

Cross.CQRS/Filters/ResultFilter.cs

@@ -0,0 +1,15 @@
+namespace Cross.CQRS.Filters;
+
+/// <summary>
+/// Base query/command filter.
+/// </summary>
+public abstract class ResultFilter<TRequest, TResult> : IResultFilter<TRequest, TResult>
+    where TRequest : IRequest<TResult>
+{
+    /// <inheritdoc />
+    public TResult ApplyFilter(TResult result)
+        => ApplyFilterAsync(result, CancellationToken.None).GetAwaiter().GetResult();
+
+    /// <inheritdoc />
+    public abstract Task<TResult> ApplyFilterAsync(TResult result, CancellationToken cancellationToken);
+}

Cross.CQRS/GlobalUsings.cs

@@ -10,6 +10,7 @@
 global using Cross.CQRS.Behaviors;
 global using Cross.CQRS.Commands;
 global using Cross.CQRS.Events;
+global using Cross.CQRS.Filters;
 global using Cross.CQRS.Queries;
 global using Cross.CQRS.Services;
 global using FluentValidation.Results;

Cross.CQRS/ServiceCollectionExtensions.cs

@@ -13,7 +13,7 @@ public static CqrsRegistrationSyntax AddCQRS(this IServiceCollection services, p
     {
         var behaviorCollection = new BehaviorCollection(services);
 
-        // FluentValidation
+        // FluentValidations
         services.AddValidatorsFromAssembly(assemblies.FirstOrDefault(), ServiceLifetime.Scoped, result =>
         {
             var isNoRegisterAutomatically = result.ValidatorType
@@ -23,6 +23,17 @@ public static CqrsRegistrationSyntax AddCQRS(this IServiceCollection services, p
             return !isNoRegisterAutomatically;
         });
 
+        // Filters
+        services.Scan(scan => scan
+            .FromAssemblies(assemblies)
+            .AddClasses(classes => classes.AssignableTo(typeof(IResultFilter<,>)))
+                .AsImplementedInterfaces()
+                .WithScopedLifetime()
+            .AddClasses(classes => classes.AssignableTo(typeof(IRequestFilter<>)))
+                .AsImplementedInterfaces()
+                .WithScopedLifetime()
+        );
+
         services.AddMediatR(o => o.AsScoped(), assemblies);
 
         services.AddSingleton<IHandlerLocator>(_ => new HandlerLocator(services));
@@ -35,6 +46,8 @@ public static CqrsRegistrationSyntax AddCQRS(this IServiceCollection services, p
         // Behaviors registered earlier will be executed earlier
         behaviorCollection.AddBehavior(typeof(EventQueueProcessBehavior<,>), order: int.MinValue);
         behaviorCollection.AddBehavior(typeof(ValidationBehavior<,>), order: 1);
+        behaviorCollection.AddBehavior(typeof(RequestFilterBehavior<,>), order: 2);
+        behaviorCollection.AddBehavior(typeof(ResultFilterBehavior<,>), order: 3);
 
         return new CqrsRegistrationSyntax(services, assemblies, behaviorCollection);
     }

README.md

@@ -20,6 +20,12 @@ Main Features:
   Implemented base patterns to crate Events, approach how to write a new Events from the Commands, consuming patterns and behavior to handle it.
   The main idea is to do some actions after the Commands have to be finished, to avoid cases when one Command call another one.
 
+* **Filters**.
+
+  Here included filter behavior based on RequestFilter and ResultFilter.
+  The RequestFilter allow to filter Queries and Commands requests before their execution.
+  The ResultFilter allow to filter Queries and Commands results after their execution.
+
 * **Validation**.
 
   Here included validation behavior based on FluentValidation, that allow to validate Queries and Command before their execution.
@@ -54,5 +60,5 @@ Note - test project is not a part of nuget package. You have to clone repository
 ## Roadmap:
 - ~~Queries implementation~~
 - ~~Commands Implementation~~
-- ~~Validation behavior~~ (based on FluentValidation)
+- ~~Validation behavior (based on FluentValidation)~~
 - ~~Events~~

ReleaseNotes.txt

@@ -38,3 +38,8 @@ Upgrade packages.
 Added NoRegisterAutomaticallyAttribute to avoid register instance of class automatically in DI.
 Small fixes.
 Added sample project.
+
+8.2.0 - 16 Apr 2024
+Added IRequestFilter with Behaviour to filter request of query or command.
+Added IResultFilter with Behaviour to filter result of query or command.
+

SampleWebApp/GlobalUsings.cs

@@ -4,9 +4,11 @@
 global using System.Collections.Generic;
 global using System.Linq;
 global using System.Text;
+global using System.Threading;
 global using System.Threading.Tasks;
 global using Cross.CQRS;
 global using Cross.CQRS.Behaviors;
+global using Cross.CQRS.Filters;
 global using Cross.CQRS.Queries;
 global using FluentValidation;
 global using Microsoft.AspNetCore.Builder;

SampleWebApp/Modules/Some/Handlers/SomeResultFilter.cs

@@ -0,0 +1,11 @@
+namespace SampleWebApp.Modules.Some.Handlers;
+
+public class SomeResultFilter : ResultFilter<SomeQuery, IEnumerable<string>>
+{
+    public override Task<IEnumerable<string>> ApplyFilterAsync(IEnumerable<string> response, CancellationToken cancellationToken)
+    {
+        // do some filter actions
+
+        return Task.FromResult(response);
+    }
+}

_nuget/config.nuspec

@@ -2,29 +2,30 @@
 <package xmlns="http://schemas.microsoft.com/packaging/2013/05/nuspec.xsd">
   <metadata>
     <id>Cross.CQRS</id>
-    <version>8.1.2</version>
+    <version>8.2.0</version>
     <authors>denis-peshkov</authors>
     <owners>denis-peshkov</owners>
+    <copyright>Copyright 2024</copyright>
     <license type="expression">MIT</license>
     <requireLicenseAcceptance>false</requireLicenseAcceptance>
     <projectUrl>https://github.com/denis-peshkov/Cross.CQRS</projectUrl>
     <repository type="git" url="https://github.com/denis-peshkov/Cross.CQRS" />
     <readme>docs\README.md</readme>
     <icon>icon.png</icon>
     <releaseNotes>
-      Added NoRegisterAutomaticallyAttribute to avoid register instance of class automatically in DI.
-      Small fixes.
-      Added sample project.
+      Added IRequestFilter with Behaviour to filter request of query or command.
+      Added IResultFilter with Behaviour to filter result of query or command.
     </releaseNotes>
-    <description>Simple .NET MediatR base Query, Command, Event. Event Queue and Validation behaviors. Written on C#.</description>
-    <tags>.NET Mediatr Query QueryHandler Command CommandHandler Event EventHandler EventQueueBehavior Validation ValidationBehavior SyntaxNotes NetCore</tags>
+    <description>Simple .NET MediatR base Query, Command, Event. RequestFilter, ResultFilter and Filter behaviours. Event Queue and Validation behaviors. Written on C#.</description>
+    <tags>.NET Mediatr Query QueryHandler Command CommandHandler Event EventHandler EventQueueBehavior Filter RequestFilter ResultFilter FilterBehavior Validation ValidationBehavior SyntaxNotes NetCore</tags>
     <dependencies>
       <dependency id="FluentValidation" version="11.8.1" />
       <dependency id="FluentValidation.DependencyInjectionExtensions" version="11.8.1" />
       <dependency id="MediatR" version="11.1.0" />
       <dependency id="MediatR.Extensions.Microsoft.DependencyInjection" version="11.1.0" />
       <dependency id="Microsoft.Extensions.Configuration" version="8.0.0" />
       <dependency id="Microsoft.CSharp" version="4.7.0" />
+      <dependency id="Scrutor" version="4.2.2" />
     </dependencies>
   </metadata>
   <files>

_nuget/pkg.bat

@@ -1,2 +1,3 @@
 dotnet build --configuration release ..\Cross.CQRS.sln
-nuget.exe pack config.nuspec -Symbols -SymbolPackageFormat snupkg
+REM nuget.exe pack config.nuspec -Symbols -SymbolPackageFormat snupkg
+nuget.exe pack config.nuspec -Symbols