Add System.Text.Json converter for EventGridEvent (#22295)

* Add System.Text.Json converter for EventGridEvent

* Usings

* Fix docs

* Use more efficient parse

sdk/eventgrid/Azure.Messaging.EventGrid/src/Customization/EventGridEvent.cs

@@ -3,12 +3,14 @@
 
 using System;
 using System.Text.Json;
+using System.Text.Json.Serialization;
 using Azure.Core;
 using Azure.Messaging.EventGrid.Models;
 
 namespace Azure.Messaging.EventGrid
 {
     /// <summary> Properties of an event published to an Event Grid topic using the EventGrid Schema. </summary>
+    [JsonConverter(typeof(EventGridEventConverter))]
     public class EventGridEvent
     {
         /// <summary> Initializes a new instance of <see cref="EventGridEvent"/>. </summary>

sdk/eventgrid/Azure.Messaging.EventGrid/src/Customization/EventGridEventConverter.cs

@@ -0,0 +1,46 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+using System;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using Azure.Core;
+using Azure.Messaging.EventGrid.Models;
+
+namespace Azure.Messaging.EventGrid
+{
+    /// <summary>
+    /// A custom converter that attributes the <see cref="EventGridEvent"/> type.
+    /// This allows System.Text.Json to serialize and deserialize EventGridEvent by default.
+    /// </summary>
+    internal class EventGridEventConverter : JsonConverter<EventGridEvent>
+    {
+        /// <summary>
+        /// Gets or sets the serializer to use for the data portion of the <see cref="EventGridEvent"/>. If not specified,
+        /// JsonObjectSerializer is used.
+        /// </summary>
+        /// <inheritdoc cref="JsonConverter{EventGridEvent}.Read(ref Utf8JsonReader, Type, JsonSerializerOptions)"/>
+        public override EventGridEvent Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+        {
+            JsonDocument requestDocument = JsonDocument.ParseValue(ref reader);
+            return new EventGridEvent(EventGridEventInternal.DeserializeEventGridEventInternal(requestDocument.RootElement));
+        }
+
+        /// <inheritdoc cref="JsonConverter{EventGridEvent}.Write(Utf8JsonWriter, EventGridEvent, JsonSerializerOptions)"/>
+        public override void Write(Utf8JsonWriter writer, EventGridEvent value, JsonSerializerOptions options)
+        {
+            JsonDocument data = JsonDocument.Parse(value.Data.ToStream());
+            var eventGridEventInternal = new EventGridEventInternal(
+                value.Id,
+                value.Subject,
+                data.RootElement,
+                value.EventType,
+                value.EventTime,
+                value.DataVersion)
+            {
+                Topic = value.Topic
+            };
+            ((IUtf8JsonSerializable) eventGridEventInternal).Write(writer);
+        }
+    }
+}

sdk/eventgrid/Azure.Messaging.EventGrid/src/Customization/EventGridPublisherClient.cs

@@ -9,7 +9,6 @@
 using System.Threading.Tasks;
 using Azure.Core;
 using Azure.Core.Pipeline;
-using Azure.Messaging.EventGrid.Models;
 
 namespace Azure.Messaging.EventGrid
 {
@@ -160,26 +159,9 @@ private async Task<Response> SendEventsInternal(IEnumerable<EventGridEvent> even
 
                 using HttpMessage message = _pipeline.CreateMessage();
                 Request request = CreateEventRequest(message, "application/json");
-                var content = new Utf8JsonRequestContent();
-                content.JsonWriter.WriteStartArray();
-                foreach (EventGridEvent egEvent in events)
-                {
-                    JsonDocument data = JsonDocument.Parse(egEvent.Data.ToStream());
-                    EventGridEventInternal newEGEvent = new EventGridEventInternal(
-                        egEvent.Id,
-                        egEvent.Subject,
-                        data.RootElement,
-                        egEvent.EventType,
-                        egEvent.EventTime,
-                        egEvent.DataVersion)
-                    {
-                        Topic = egEvent.Topic
-                    };
-                    content.JsonWriter.WriteObjectValue(newEGEvent);
-                }
 
-                content.JsonWriter.WriteEndArray();
-                request.Content = content;
+                // leverage custom converter for EventGridEvent
+                request.Content = RequestContent.Create(JsonSerializer.Serialize(events));
 
                 if (async)
                 {

sdk/eventgrid/Azure.Messaging.EventGrid/tests/ConsumeEventTests.cs

@@ -31,6 +31,21 @@ public void ParsesEventGridEnvelope()
             Assert.AreEqual("1", egEvent.DataVersion);
         }
 
+        [Test]
+        public void ParsesEventGridEnvelopeUsingConverter()
+        {
+            string requestContent = "[{  \"id\": \"2d1781af-3a4c-4d7c-bd0c-e34b19da4e66\",  \"topic\": \"/subscriptions/xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx\",  \"subject\": \"mySubject\",  \"data\": {    \"validationCode\": \"512d38b6-c7b8-40c8-89fe-f46f9e9622b6\",    \"validationUrl\": \"https://rp-eastus2.eventgrid.azure.net:553/eventsubscriptions/estest/validate?id=B2E34264-7D71-453A-B5FB-B62D0FDC85EE&t=2018-04-26T20:30:54.4538837Z&apiVersion=2018-05-01-preview&token=1BNqCxBBSSE9OnNSfZM4%2b5H9zDegKMY6uJ%2fO2DFRkwQ%3d\"  },  \"eventType\": \"Microsoft.EventGrid.SubscriptionValidationEvent\",  \"eventTime\": \"2018-01-25T22:12:19.4556811Z\",  \"metadataVersion\": \"1\",  \"dataVersion\": \"1\"}]";
+
+            EventGridEvent[] events = JsonSerializer.Deserialize<EventGridEvent[]>(requestContent);
+            var egEvent = events[0];
+            Assert.AreEqual("/subscriptions/xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx", egEvent.Topic);
+            Assert.AreEqual("2d1781af-3a4c-4d7c-bd0c-e34b19da4e66", egEvent.Id);
+            Assert.AreEqual("mySubject", egEvent.Subject);
+            Assert.AreEqual(SystemEventNames.EventGridSubscriptionValidation, egEvent.EventType);
+            Assert.AreEqual(DateTimeOffset.Parse("2018-01-25T22:12:19.4556811Z"), egEvent.EventTime);
+            Assert.AreEqual("1", egEvent.DataVersion);
+        }
+
         [Test]
         public void ConsumeStorageBlobDeletedEventWithExtraProperty()
         {
@@ -72,6 +87,23 @@ public void ConsumeEventNotWrappedInAnArray()
             }
         }
 
+        [Test]
+        public void ConsumeEventNotWrappedInAnArrayWithConverter()
+        {
+            string requestContent = "{  \"topic\": \"/subscriptions/id/resourceGroups/Storage/providers/Microsoft.Storage/storageAccounts/xstoretestaccount\",  \"subject\": \"/blobServices/default/containers/testcontainer/blobs/testfile.txt\",  \"eventType\": \"Microsoft.Storage.BlobDeleted\",  \"eventTime\": \"2017-11-07T20:09:22.5674003Z\",  \"id\": \"4c2359fe-001e-00ba-0e04-58586806d298\",  \"data\": {    \"api\": \"DeleteBlob\",    \"requestId\": \"4c2359fe-001e-00ba-0e04-585868000000\",    \"contentType\": \"text/plain\",    \"blobType\": \"BlockBlob\",    \"url\": \"https://example.blob.core.windows.net/testcontainer/testfile.txt\",    \"sequencer\": \"0000000000000281000000000002F5CA\",   \"brandNewProperty\": \"0000000000000281000000000002F5CA\", \"storageDiagnostics\": {      \"batchId\": \"b68529f3-68cd-4744-baa4-3c0498ec19f0\"    }  },  \"dataVersion\": \"\",  \"metadataVersion\": \"1\"}";
+
+            EventGridEvent egEvent = JsonSerializer.Deserialize<EventGridEvent>(requestContent);
+
+            Assert.NotNull(egEvent);
+            switch (egEvent.EventType)
+            {
+                case SystemEventNames.StorageBlobDeleted:
+                    StorageBlobDeletedEventData blobDeleted = egEvent.Data.ToObjectFromJson<StorageBlobDeletedEventData>();
+                    Assert.AreEqual("https://example.blob.core.windows.net/testcontainer/testfile.txt", blobDeleted.Url);
+                    break;
+            }
+        }
+
         [Test]
         public void ConsumeMultipleEventsInSameBatch()
         {

sdk/eventgrid/Azure.Messaging.EventGrid/tests/EventGridEventTests.cs

@@ -140,7 +140,7 @@ public async Task RespectsPortFromUriSendingEventGridEvents()
 
         private static List<EventGridEvent> DeserializeRequest(Request request)
         {
-            var content = request.Content as Utf8JsonRequestContent;
+            var content = request.Content;
             var stream = new MemoryStream();
             content.WriteTo(stream, CancellationToken.None);
             stream.Position = 0;