fix(errors): error objects should be a collection

Author: jaredcnance

src/JsonApiDotNetCore/Formatters/JsonApiOutputFormatter.cs

@@ -37,36 +37,52 @@ public async Task WriteAsync(OutputFormatterWriteContext context)
             using (var writer = context.WriterFactory(response.Body, Encoding.UTF8))
             {
                 var jsonApiContext = GetService<IJsonApiContext>(context);
-                
+
+                response.ContentType = "application/vnd.api+json";
                 string responseContent;
                 try
                 {
-                    if(context.Object.GetType() == typeof(Error) || jsonApiContext.RequestEntity == null)
-                    {
-                        logger?.LogInformation("Response was not a JSONAPI entity. Serializing as plain JSON.");
-                        responseContent = JsonConvert.SerializeObject(context.Object);
-                    }
-                    else
-                    {
-                        response.ContentType = "application/vnd.api+json";
-                        responseContent = JsonApiSerializer.Serialize(context.Object, jsonApiContext);
-                    }
+                    responseContent = GetResponseBody(context.Object, jsonApiContext, logger);
                 }
-                catch(Exception e)
+                catch (Exception e)
                 {
                     logger?.LogError(new EventId(), e, "An error ocurred while formatting the response");
-                    responseContent = new Error("400", e.Message).GetJson();
+                    var errors = new ErrorCollection();
+                    errors.Add(new Error("400", e.Message));
+                    responseContent = errors.GetJson();
                     response.StatusCode = 400;
                 }
-                
+
                 await writer.WriteAsync(responseContent);
-                await writer.FlushAsync();       
+                await writer.FlushAsync();
             }
         }
 
         private T GetService<T>(OutputFormatterWriteContext context)
         {
             return context.HttpContext.RequestServices.GetService<T>();
         }
+
+        private string GetResponseBody(object responseObject, IJsonApiContext jsonApiContext, ILogger logger)
+        {
+            if (responseObject.GetType() == typeof(Error) || jsonApiContext.RequestEntity == null)
+            {
+                if (responseObject.GetType() == typeof(Error))
+                {
+                    var errors = new ErrorCollection();
+                    errors.Add((Error)responseObject);
+                    return errors.GetJson();
+                }
+                else
+                {
+                    logger?.LogInformation("Response was not a JSONAPI entity. Serializing as plain JSON.");
+                    return JsonConvert.SerializeObject(responseObject);
+                }
+            }
+            else
+            {
+                return JsonApiSerializer.Serialize(responseObject, jsonApiContext);
+            }
+        }
     }
 }

src/JsonApiDotNetCore/Internal/Error.cs

@@ -28,12 +28,5 @@ public Error(string status, string title, string detail)
 
         [JsonProperty("status")]
         public string Status { get; set; }
-
-        public string GetJson()
-        {
-            return JsonConvert.SerializeObject(this, new JsonSerializerSettings {
-                NullValueHandling = NullValueHandling.Ignore
-            });
-        }
     }
 }

src/JsonApiDotNetCore/Internal/ErrorCollection.cs

@@ -0,0 +1,27 @@
+using System.Collections.Generic;
+using Newtonsoft.Json;
+
+namespace JsonApiDotNetCore.Internal
+{
+    public class ErrorCollection
+    {
+        public ErrorCollection()
+        { 
+            Errors = new List<Error>();
+        }
+        
+        public List<Error> Errors { get; set; }
+
+        public void Add(Error error)
+        {
+            Errors.Add(error);
+        }
+
+        public string GetJson()
+        {
+            return JsonConvert.SerializeObject(this, new JsonSerializerSettings {
+                NullValueHandling = NullValueHandling.Ignore
+            });
+        }
+    }
+}

test/JsonApiDotNetCoreExampleTests/Acceptance/Spec/QueryParameters.cs

@@ -39,11 +39,12 @@ public async Task Server_Returns_400_ForUnknownQueryParam()
 
             // act
             var response = await client.SendAsync(request);
-            var body = JsonConvert.DeserializeObject<Error>(await response.Content.ReadAsStringAsync());
+            var body = JsonConvert.DeserializeObject<ErrorCollection>(await response.Content.ReadAsStringAsync());
 
             // assert
             Assert.Equal(HttpStatusCode.BadRequest, response.StatusCode);
-            Assert.Equal($"[{queryKey}, {queryValue}] is not a valid query.", body.Title);
+            Assert.Equal(1, body.Errors.Count);
+            Assert.Equal($"[{queryKey}, {queryValue}] is not a valid query.", body.Errors[0].Title);
         }
     }
 }