Support for custom HTTP status code exception handlers

JamesRandall · May 31, 2019 · 72849bd · 72849bd
1 parent 9fbe97c
commit 72849bd
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Showing 6 changed files with 48 additions and 11 deletions.
diff --git a/Source/AzureFromTheTrenches.Commanding.Http/AzureFromTheTrenches.Commanding.Http.csproj b/Source/AzureFromTheTrenches.Commanding.Http/AzureFromTheTrenches.Commanding.Http.csproj
@@ -16,6 +16,7 @@
     <AssemblyVersion>9.0.1.0</AssemblyVersion>
     <FileVersion>9.0.1.0</FileVersion>
     <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
+    <PackageVersion>9.1.1</PackageVersion>
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|AnyCPU'">

diff --git a/Source/AzureFromTheTrenches.Commanding.Http/HttpCommandDispatcherFactory.cs b/Source/AzureFromTheTrenches.Commanding.Http/HttpCommandDispatcherFactory.cs
@@ -1,10 +1,19 @@
 using System;
+using System.Net;
 using System.Net.Http;
 using AzureFromTheTrenches.Commanding.Abstractions;
 using AzureFromTheTrenches.Commanding.Http.Implementation;
 
 namespace AzureFromTheTrenches.Commanding.Http
 {
+    /// <summary>
+    /// A delegate used for custom exception raising when HTTP calls fail
+    /// </summary>
+    /// <param name="statusCode">The (non-success) HTTP status code</param>
+    /// <param name="requestUri">The URI that was called</param>
+    /// <param name="command">The command that triggered the error</param>
+    public delegate Exception HttpDispatchErrorHandler(HttpStatusCode statusCode, Uri requestUri, ICommand command);
+
     /// <summary>
     /// Creates HTTP command dispatcher functions
     /// </summary>
@@ -28,13 +37,14 @@ public static class HttpCommandDispatcherFactory
             HttpMethod httpMethod = null,
             Func<string> authenticationHeaderContent = null,
             IHttpCommandSerializer serializer = null,
-            IUriCommandQueryBuilder uriCommandQueryBuilder = null)
+            IUriCommandQueryBuilder uriCommandQueryBuilder = null,
+            HttpDispatchErrorHandler httpDispatchErrorHandler = null)
         {
             return () => 
                 new HttpCommandDispatcherFactoryImpl(
                     serializer ?? new JsonCommandSerializer(),
                     uriCommandQueryBuilder ?? new UriCommandQueryBuilder(),
-                    HttpClientProvider).Create(uri, httpMethod, authenticationHeaderContent);
+                    HttpClientProvider).Create(uri, httpMethod, authenticationHeaderContent, httpDispatchErrorHandler);
         }
     }
 }
diff --git a/Source/AzureFromTheTrenches.Commanding.Http/ICommandRegistryExtensions.cs b/Source/AzureFromTheTrenches.Commanding.Http/ICommandRegistryExtensions.cs
@@ -13,13 +13,15 @@ public static class ICommandRegistryExtensions
             HttpMethod httpMethod = null,
             Func<string> authenticationHeaderContent = null,
             IHttpCommandSerializer httpCommandSerializer = null,
-            IUriCommandQueryBuilder uriCommandQueryBuilder = null) where TCommand : ICommand<TResult>
+            IUriCommandQueryBuilder uriCommandQueryBuilder = null,
+            HttpDispatchErrorHandler httpDispatchErrorHandler = null) where TCommand : ICommand<TResult>
         {
             registry.Register<TCommand, TResult>(() => new HttpCommandDispatcher(new HttpCommandExecuter(
                 uri,
                 httpMethod, authenticationHeaderContent, httpCommandSerializer ?? new JsonCommandSerializer(),
                 uriCommandQueryBuilder ?? new UriCommandQueryBuilder(),
-                HttpCommandingDependencies.HttpClientProvider)));
+                HttpCommandingDependencies.HttpClientProvider,
+                httpDispatchErrorHandler)));
         }
     }
 }
diff --git a/Source/AzureFromTheTrenches.Commanding.Http/IHttpCommandDispatcherFactory.cs b/Source/AzureFromTheTrenches.Commanding.Http/IHttpCommandDispatcherFactory.cs
@@ -6,6 +6,9 @@ namespace AzureFromTheTrenches.Commanding.Http
 {
     public interface IHttpCommandDispatcherFactory
     {
-        ICommandDispatcher Create(Uri uri, HttpMethod httpMethod = null, Func<string> authenticationHeaderContent = null);
+        ICommandDispatcher Create(Uri uri,
+            HttpMethod httpMethod = null,
+            Func<string> authenticationHeaderContent = null,
+            HttpDispatchErrorHandler httpDispatchErrorHandler = null);
     }
 }
diff --git a/...e/AzureFromTheTrenches.Commanding.Http/Implementation/HttpCommandDispatcherFactoryImpl.cs b/...e/AzureFromTheTrenches.Commanding.Http/Implementation/HttpCommandDispatcherFactoryImpl.cs
@@ -19,15 +19,19 @@ internal class HttpCommandDispatcherFactoryImpl : IHttpCommandDispatcherFactory
             _httpClientProvider = httpClientProvider;
         }
 
-        public ICommandDispatcher Create(Uri uri, HttpMethod httpMethod = null, Func<string> authenticationHeaderContent = null)
+        public ICommandDispatcher Create(Uri uri,
+            HttpMethod httpMethod = null,
+            Func<string> authenticationHeaderContent = null,
+            HttpDispatchErrorHandler httpDispatchErrorHandler = null)
         {
             return new HttpCommandDispatcher(new HttpCommandExecuter(
                 uri,
                 httpMethod,
                 authenticationHeaderContent,
                 _httpCommandSerializer,
                 _uriCommandQueryBuilder,
-                _httpClientProvider));
+                _httpClientProvider,
+                httpDispatchErrorHandler));
         }
     }
 }
diff --git a/Source/AzureFromTheTrenches.Commanding.Http/Implementation/HttpCommandExecuter.cs b/Source/AzureFromTheTrenches.Commanding.Http/Implementation/HttpCommandExecuter.cs
@@ -16,21 +16,23 @@ internal class HttpCommandExecuter : ICommandExecuter
         private readonly IHttpCommandSerializer _serializer;
         private readonly IUriCommandQueryBuilder _uriCommandQueryBuilder;
         private readonly IHttpClientProvider _httpClientProvider;
+        private readonly HttpDispatchErrorHandler _httpDispatchErrorHandler;
 
-        public HttpCommandExecuter(
-            Uri uri,
+        public HttpCommandExecuter(Uri uri,
             HttpMethod httpMethod,
             Func<string> authenticationHeaderContent,
             IHttpCommandSerializer serializer,
             IUriCommandQueryBuilder uriCommandQueryBuilder,
-            IHttpClientProvider httpClientProvider)
+            IHttpClientProvider httpClientProvider,
+            HttpDispatchErrorHandler httpDispatchErrorHandler)
         {
             _uri = uri;
             _httpMethod = httpMethod ?? HttpMethod.Post;
             _authenticationHeaderContent = authenticationHeaderContent;
             _serializer = serializer;
             _uriCommandQueryBuilder = uriCommandQueryBuilder;
             _httpClientProvider = httpClientProvider;
+            _httpDispatchErrorHandler = httpDispatchErrorHandler;
         }
 
         public async Task<TResult> ExecuteAsync<TResult>(ICommand<TResult> command, CancellationToken cancellationToken)
@@ -65,7 +67,22 @@ public async Task<TResult> ExecuteAsync<TResult>(ICommand<TResult> command, Canc
             }
 
             HttpResponseMessage responseMessage = await _httpClientProvider.Client.SendAsync(requestMessage, cancellationToken);
-            responseMessage.EnsureSuccessStatusCode();
+            if (!responseMessage.IsSuccessStatusCode)
+            {
+                if (_httpDispatchErrorHandler != null)
+                {
+                    Exception exception = _httpDispatchErrorHandler.Invoke(responseMessage.StatusCode, requestMessage.RequestUri, command);
+                    if (exception != null)
+                    {
+                        throw exception;
+                    }
+                }
+
+                // if we don't throw an exception from the custom handler then have the build in HTTP error handling
+                // kick in
+                responseMessage.EnsureSuccessStatusCode();
+            }
+
             string result = await responseMessage.Content.ReadAsStringAsync();
             return _serializer.Deserialize<TResult>(result);
         }