Custom command middlewares.

src/Squidex.Infrastructure/Commands/CustomCommandMiddlewareRunner.cs

@@ -0,0 +1,41 @@
+// ==========================================================================
+//  Squidex Headless CMS
+// ==========================================================================
+//  Copyright (c) Squidex UG (haftungsbeschraenkt)
+//  All rights reserved. Licensed under the MIT license.
+// ==========================================================================
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace Squidex.Infrastructure.Commands
+{
+    public sealed class CustomCommandMiddlewareRunner : ICommandMiddleware
+    {
+        private readonly IEnumerable<ICustomCommandMiddleware> extensions;
+
+        public CustomCommandMiddlewareRunner(IEnumerable<ICustomCommandMiddleware> extensions)
+        {
+            Guard.NotNull(extensions, nameof(extensions));
+
+            this.extensions = extensions.Reverse().ToList();
+        }
+
+        public async Task HandleAsync(CommandContext context, Func<Task> next)
+        {
+            foreach (var handler in extensions)
+            {
+                next = Join(handler, context, next);
+            }
+
+            await next();
+        }
+
+        private static Func<Task> Join(ICommandMiddleware handler, CommandContext context, Func<Task> next)
+        {
+            return () => handler.HandleAsync(context, next);
+        }
+    }
+}

src/Squidex.Infrastructure/Commands/ICustomCommandMiddleware.cs

@@ -0,0 +1,13 @@
+// ==========================================================================
+//  Squidex Headless CMS
+// ==========================================================================
+//  Copyright (c) Squidex UG (haftungsbeschraenkt)
+//  All rights reserved. Licensed under the MIT license.
+// ==========================================================================
+
+namespace Squidex.Infrastructure.Commands
+{
+    public interface ICustomCommandMiddleware : ICommandMiddleware
+    {
+    }
+}

src/Squidex/Config/Domain/EntitiesServices.cs

@@ -227,6 +227,9 @@ namespace Squidex.Config.Domain
             services.AddSingletonAs<EnrichWithSchemaIdCommandMiddleware>()
                 .As<ICommandMiddleware>();
 
+            services.AddSingletonAs<CustomCommandMiddlewareRunner>()
+                .As<ICommandMiddleware>();
+
             services.AddSingletonAs<InviteUserCommandMiddleware>()
                 .As<ICommandMiddleware>();
 

tests/Squidex.Infrastructure.Tests/Commands/CustomCommandMiddlewareRunnerTests.cs

@@ -0,0 +1,72 @@
+// ==========================================================================
+//  Squidex Headless CMS
+// ==========================================================================
+//  Copyright (c) Squidex UG (haftungsbeschraenkt)
+//  All rights reserved. Licensed under the MIT license.
+// ==========================================================================
+
+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using FakeItEasy;
+using Xunit;
+
+namespace Squidex.Infrastructure.Commands
+{
+    public class CustomCommandMiddlewareRunnerTests
+    {
+        public sealed class Command : ICommand
+        {
+            public List<int> Values { get; set; } = new List<int>();
+
+            public long ExpectedVersion { get; set; }
+        }
+
+        public sealed class CustomMiddleware : ICustomCommandMiddleware
+        {
+            private readonly int value;
+
+            public CustomMiddleware(int value)
+            {
+                this.value = value;
+            }
+
+            public Task HandleAsync(CommandContext context, Func<Task> next)
+            {
+                if (context.Command is Command command)
+                {
+                    command.Values.Add(value);
+                }
+
+                return next();
+            }
+        }
+
+        [Fact]
+        public async Task Should_run_extensions_in_right_order()
+        {
+            var command = new Command();
+            var context = new CommandContext(command, A.Fake<ICommandBus>());
+
+            var sut = new CustomCommandMiddlewareRunner(new[]
+            {
+                new CustomMiddleware(10),
+                new CustomMiddleware(12),
+                new CustomMiddleware(14)
+            });
+
+            var isNextCalled = false;
+
+            await sut.HandleAsync(context, () =>
+            {
+                isNextCalled = true;
+
+                Assert.Equal(new[] { 10, 12, 14 }, command.Values);
+
+                return Task.CompletedTask;
+            });
+
+            Assert.True(isNextCalled);
+        }
+    }
+}