allow to add delegating handlers by type (#943)

src/Ocelot/DependencyInjection/IOcelotBuilder.cs

@@ -1,6 +1,7 @@
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
 using Ocelot.Middleware.Multiplexer;
+using System;
 using System.Net.Http;
 
 namespace Ocelot.DependencyInjection
@@ -13,6 +14,8 @@ namespace Ocelot.DependencyInjection
 
         IMvcCoreBuilder MvcCoreBuilder { get; }
 
+        IOcelotBuilder AddDelegatingHandler(Type type, bool global = false);
+
         IOcelotBuilder AddDelegatingHandler<T>(bool global = false)
             where T : DelegatingHandler;
 

src/Ocelot/DependencyInjection/OcelotBuilder.cs

@@ -35,6 +35,7 @@ namespace Ocelot.DependencyInjection
     using Ocelot.Security;
     using Ocelot.Security.IPSecurity;
     using Ocelot.ServiceDiscovery;
+    using System;
     using System.Net.Http;
     using System.Reflection;
 
@@ -165,6 +166,28 @@ namespace Ocelot.DependencyInjection
             Services.TryAddSingleton<ISecurityPolicy, IPSecurityPolicy>();
         }
 
+        public IOcelotBuilder AddDelegatingHandler(Type delegateType, bool global = false)
+        {
+            if (!typeof(DelegatingHandler).IsAssignableFrom(delegateType)) throw new ArgumentOutOfRangeException(nameof(delegateType), delegateType.Name, "It is not a delegatin handler");
+
+            if (global)
+            {
+                Services.AddTransient(delegateType);
+                Services.AddTransient<GlobalDelegatingHandler>(s =>
+                {
+
+                    var service = s.GetService(delegateType) as DelegatingHandler;
+                    return new GlobalDelegatingHandler(service);
+                });
+            }
+            else
+            {
+                Services.AddTransient(typeof(DelegatingHandler), delegateType);
+            }
+
+            return this;
+        }
+
         public IOcelotBuilder AddDelegatingHandler<THandler>(bool global = false)
             where THandler : DelegatingHandler
         {

test/Ocelot.UnitTests/DependencyInjection/OcelotBuilderTests.cs

@@ -47,6 +47,17 @@ namespace Ocelot.UnitTests.DependencyInjection
                 .BDDfy();
         }
 
+        [Fact]
+        public void should_add_type_specific_delegating_handlers_transient()
+        {
+            this.Given(x => WhenISetUpOcelotServices())
+                .When(x => AddTypeSpecificTransientDelegatingHandler(typeof(FakeDelegatingHandler)))
+                .And(x => AddTypeSpecificTransientDelegatingHandler(typeof(FakeDelegatingHandlerTwo)))
+                .Then(x => ThenTheProviderIsRegisteredAndReturnsSpecificHandlers<FakeDelegatingHandler, FakeDelegatingHandlerTwo>())
+                .And(x => ThenTheSpecificHandlersAreTransient())
+                .BDDfy();
+        }
+
         [Fact]
         public void should_add_global_delegating_handlers_transient()
         {
@@ -58,6 +69,17 @@ namespace Ocelot.UnitTests.DependencyInjection
                 .BDDfy();
         }
 
+        [Fact]
+        public void should_add_global_type_delegating_handlers_transient()
+        {
+            this.Given(x => WhenISetUpOcelotServices())
+                .When(x => AddTransientGlobalDelegatingHandler<FakeDelegatingHandler>())
+                .And(x => AddTransientGlobalDelegatingHandler<FakeDelegatingHandlerTwo>())
+                .Then(x => ThenTheProviderIsRegisteredAndReturnsHandlers<FakeDelegatingHandler, FakeDelegatingHandlerTwo>())
+                .And(x => ThenTheGlobalHandlersAreTransient())
+                .BDDfy();
+        }
+
         [Fact]
         public void should_set_up_services()
         {
@@ -156,6 +178,16 @@ namespace Ocelot.UnitTests.DependencyInjection
             _ocelotBuilder.AddDelegatingHandler<T>();
         }
 
+        private void AddTypeTransientGlobalDelegatingHandler(Type type)
+        {
+            _ocelotBuilder.AddDelegatingHandler(type, true);
+        }
+
+        private void AddTypeSpecificTransientDelegatingHandler(Type type)
+        {
+            _ocelotBuilder.AddDelegatingHandler(type);
+        }
+
         private void ThenTheProviderIsRegisteredAndReturnsHandlers<TOne, TWo>()
         {
             _serviceProvider = _services.BuildServiceProvider();