Return content on failed http requests

src/GraphQL.Client/GraphQLHttpClient.cs

@@ -1,8 +1,8 @@
 using System;
 using System.Collections.Concurrent;
 using System.Diagnostics;
+using System.IO;
 using System.Net.Http;
-using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
 using GraphQL.Client.Abstractions;
@@ -73,7 +73,7 @@ public async Task<GraphQLResponse<TResponse>> SendQueryAsync<TResponse>(GraphQLR
             if (Options.UseWebSocketForQueriesAndMutations)
                 return await _graphQlHttpWebSocket.SendRequest<TResponse>(request, cancellationToken);
 
-            return await SendHttpPostRequestAsync<TResponse>(request, cancellationToken);
+            return await SendHttpRequestAsync<TResponse>(request, cancellationToken);
         }
 
         /// <inheritdoc />
@@ -124,35 +124,33 @@ public IObservable<GraphQLResponse<TResponse>> CreateSubscriptionStream<TRespons
 
         #region Private Methods
 
-        private async Task<GraphQLHttpResponse<TResponse>> SendHttpPostRequestAsync<TResponse>(GraphQLRequest request, CancellationToken cancellationToken = default)
+        private async Task<GraphQLHttpResponse<TResponse>> SendHttpRequestAsync<TResponse>(GraphQLRequest request, CancellationToken cancellationToken = default)
         {
             var preprocessedRequest = await Options.PreprocessRequest(request, this);
-            using var httpRequestMessage = GenerateHttpRequestMessage(preprocessedRequest);
-            using var httpResponseMessage = await HttpClient.SendAsync(httpRequestMessage, cancellationToken);
-
-            httpResponseMessage.EnsureSuccessStatusCode();
 
-            var bodyStream = await httpResponseMessage.Content.ReadAsStreamAsync();
-            var response = await JsonSerializer.DeserializeFromUtf8StreamAsync<TResponse>(bodyStream, cancellationToken);
-            return response.ToGraphQLHttpResponse(httpResponseMessage.Headers, httpResponseMessage.StatusCode);
-        }
+            using var httpRequestMessage = preprocessedRequest.ToHttpRequestMessage(Options, JsonSerializer);
+            using var httpResponseMessage = await HttpClient.SendAsync(httpRequestMessage, HttpCompletionOption.ResponseHeadersRead, cancellationToken);
 
-        private HttpRequestMessage GenerateHttpRequestMessage(GraphQLRequest request)
-        {
-            var message = new HttpRequestMessage(HttpMethod.Post, Options.EndPoint)
+            var contentStream = await httpResponseMessage.Content.ReadAsStreamAsync();
+
+            if (httpResponseMessage.IsSuccessStatusCode)
             {
-                Content = new StringContent(JsonSerializer.SerializeToString(request), Encoding.UTF8, Options.MediaType)
-            };
+                var graphQLResponse = await JsonSerializer.DeserializeFromUtf8StreamAsync<TResponse>(contentStream, cancellationToken);
+                return graphQLResponse.ToGraphQLHttpResponse(httpResponseMessage.Headers, httpResponseMessage.StatusCode);
+            }
 
-            if (request is GraphQLHttpRequest httpRequest)
-                httpRequest.PreprocessHttpRequestMessage(message);
+            // error handling
+            string content = null;
+            if (contentStream != null)
+                using (var sr = new StreamReader(contentStream))
+                    content = await sr.ReadToEndAsync();
 
-            return message;
+            throw new GraphQLHttpRequestException(httpResponseMessage.StatusCode, httpResponseMessage.Headers, content);
         }
 
         private Uri GetWebSocketUri()
         {
-            var webSocketSchema = Options.EndPoint.Scheme == "https" ? "wss" : "ws";
+            string webSocketSchema = Options.EndPoint.Scheme == "https" ? "wss" : "ws";
             return new Uri($"{webSocketSchema}://{Options.EndPoint.Host}:{Options.EndPoint.Port}{Options.EndPoint.AbsolutePath}");
         }
 

src/GraphQL.Client/GraphQLHttpClientOptions.cs

@@ -45,7 +45,8 @@ public class GraphQLHttpClientOptions
         /// <summary>
         /// Request preprocessing function. Can be used i.e. to inject authorization info into a GraphQL request payload.
         /// </summary>
-        public Func<GraphQLRequest, GraphQLHttpClient, Task<GraphQLRequest>> PreprocessRequest { get; set; } = (request, client) => Task.FromResult(request);
+        public Func<GraphQLRequest, GraphQLHttpClient, Task<GraphQLHttpRequest>> PreprocessRequest { get; set; } = (request, client) =>
+            Task.FromResult(request is GraphQLHttpRequest graphQLHttpRequest ? graphQLHttpRequest : new GraphQLHttpRequest(request));
 
         /// <summary>
         /// This callback is called after successfully establishing a websocket connection but before any regular request is made. 

src/GraphQL.Client/GraphQLHttpRequest.cs

@@ -1,6 +1,8 @@
 using System;
 using System.Net.Http;
 using System.Runtime.Serialization;
+using System.Text;
+using GraphQL.Client.Abstractions;
 
 namespace GraphQL.Client.Http
 {
@@ -15,10 +17,33 @@ public GraphQLHttpRequest(string query, object? variables = null, string? operat
         {
         }
 
+        public GraphQLHttpRequest(GraphQLRequest other): base(other.Query, other.Variables, other.OperationName)
+        {
+        }
+
         /// <summary>
         /// Allows to preprocess a <see cref="HttpRequestMessage"/> before it is sent, i.e. add custom headers
         /// </summary>
         [IgnoreDataMember]
+        [Obsolete("Inherit from GraphQLHttpRequest and override ToHttpRequestMessage() to customize the HttpRequestMessage. Will be removed in v4.0.0.")]
         public Action<HttpRequestMessage> PreprocessHttpRequestMessage { get; set; } = message => { };
+
+        /// <summary>
+        /// Creates a <see cref="HttpRequestMessage"/> from this <see cref="GraphQLHttpRequest"/>.
+        /// Used by <see cref="GraphQLHttpClient"/> to convert GraphQL requests when sending them as regular HTTP requests.
+        /// </summary>
+        /// <param name="options">the <see cref="GraphQLHttpClientOptions"/> passed from <see cref="GraphQLHttpClient"/></param>
+        /// <param name="serializer">the <see cref="IGraphQLJsonSerializer"/> passed from <see cref="GraphQLHttpClient"/></param>
+        /// <returns></returns>
+        public virtual HttpRequestMessage ToHttpRequestMessage(GraphQLHttpClientOptions options, IGraphQLJsonSerializer serializer)
+        {
+            var message = new HttpRequestMessage(HttpMethod.Post, options.EndPoint)
+            {
+                Content = new StringContent(serializer.SerializeToString(this), Encoding.UTF8, options.MediaType)
+            };
+
+            PreprocessHttpRequestMessage(message);
+            return message;
+        }
     }
 }

src/GraphQL.Client/GraphQLHttpRequestException.cs

@@ -0,0 +1,41 @@
+using System;
+using System.Net;
+using System.Net.Http.Headers;
+
+namespace GraphQL.Client.Http
+{
+
+    /// <summary>
+    /// An exception thrown on unexpected <see cref="System.Net.Http.HttpResponseMessage"/>
+    /// </summary>
+    public class GraphQLHttpRequestException : Exception
+    {
+        /// <summary>
+        /// The returned status code
+        /// </summary>
+        public HttpStatusCode StatusCode { get; }
+
+        /// <summary>
+        /// the returned response headers
+        /// </summary>
+        public HttpResponseHeaders ResponseHeaders { get; }
+
+        /// <summary>
+        /// the returned content
+        /// </summary>
+        public string? Content { get; }
+
+        /// <summary>
+        /// Creates a new instance of <see cref="GraphQLHttpRequestException"/>
+        /// </summary>
+        /// <param name="statusCode"></param>
+        /// <param name="responseHeaders"></param>
+        /// <param name="content"></param>
+        public GraphQLHttpRequestException(HttpStatusCode statusCode, HttpResponseHeaders responseHeaders, string? content) : base($"The HTTP request failed with status code {statusCode}")
+        {
+            StatusCode = statusCode;
+            ResponseHeaders = responseHeaders;
+            Content = content;
+        }
+    }
+}