Implement public JObject conversions in JsonEventFormatter

The method names are consistent with the ones in ProtobufEventFormatter.
Currently batch conversion is not supported, but we can add that later if requested.

Signed-off-by: Jon Skeet <[email protected]>

src/CloudNative.CloudEvents.NewtonsoftJson/JsonEventFormatter.cs

@@ -136,7 +136,7 @@ public override async Task<CloudEvent> DecodeStructuredModeMessageAsync(Stream b
 
             var jsonReader = CreateJsonReader(body, MimeUtilities.GetEncoding(contentType));
             var jObject = await JObject.LoadAsync(jsonReader).ConfigureAwait(false);
-            return DecodeJObject(jObject, extensionAttributes);
+            return DecodeJObject(jObject, extensionAttributes, nameof(body));
         }
 
         /// <inheritdoc />
@@ -146,7 +146,7 @@ public override CloudEvent DecodeStructuredModeMessage(Stream body, ContentType?
 
             var jsonReader = CreateJsonReader(body, MimeUtilities.GetEncoding(contentType));
             var jObject = JObject.Load(jsonReader);
-            return DecodeJObject(jObject, extensionAttributes);
+            return DecodeJObject(jObject, extensionAttributes, nameof(body));
         }
 
         /// <inheritdoc />
@@ -177,14 +177,23 @@ public override IReadOnlyList<CloudEvent> DecodeBatchModeMessage(Stream body, Co
         public override IReadOnlyList<CloudEvent> DecodeBatchModeMessage(ReadOnlyMemory<byte> body, ContentType? contentType, IEnumerable<CloudEventAttribute>? extensionAttributes) =>
             DecodeBatchModeMessage(BinaryDataUtilities.AsStream(body), contentType, extensionAttributes);
 
+        /// <summary>
+        /// Converts the given <see cref="JObject"/> into a <see cref="CloudEvent"/>.
+        /// </summary>
+        /// <param name="jObject">The JSON representation of a CloudEvent. Must not be null.</param>
+        /// <param name="extensionAttributes">The extension attributes to use when populating the CloudEvent. May be null.</param>
+        /// <returns>The SDK representation of the CloudEvent.</returns>
+        public CloudEvent ConvertFromJObject(JObject jObject, IEnumerable<CloudEventAttribute>? extensionAttributes) =>
+            DecodeJObject(Validation.CheckNotNull(jObject, nameof(jObject)), extensionAttributes, nameof(jObject));
+
         private IReadOnlyList<CloudEvent> DecodeJArray(JArray jArray, IEnumerable<CloudEventAttribute>? extensionAttributes, string paramName)
         {
             List<CloudEvent> events = new List<CloudEvent>(jArray.Count);
             foreach (var token in jArray)
             {
                 if (token is JObject obj)
                 {
-                    events.Add(DecodeJObject(obj, extensionAttributes));
+                    events.Add(DecodeJObject(obj, extensionAttributes, paramName));
                 }
                 else
                 {
@@ -194,7 +203,7 @@ private IReadOnlyList<CloudEvent> DecodeJArray(JArray jArray, IEnumerable<CloudE
             return events;
         }
 
-        private CloudEvent DecodeJObject(JObject jObject, IEnumerable<CloudEventAttribute>? extensionAttributes)
+        private CloudEvent DecodeJObject(JObject jObject, IEnumerable<CloudEventAttribute>? extensionAttributes, string paramName)
         {
             if (!jObject.TryGetValue(CloudEventsSpecVersion.SpecVersionAttribute.Name, out var specVersionToken)
                 || specVersionToken.Type != JTokenType.String)
@@ -207,9 +216,7 @@ private CloudEvent DecodeJObject(JObject jObject, IEnumerable<CloudEventAttribut
             var cloudEvent = new CloudEvent(specVersion, extensionAttributes);
             PopulateAttributesFromStructuredEvent(cloudEvent, jObject);
             PopulateDataFromStructuredEvent(cloudEvent, jObject);
-            // "data" is always the parameter from the public method. It's annoying not to be able to use
-            // nameof here, but this will give the appropriate result.
-            return Validation.CheckCloudEventArgument(cloudEvent, "data");
+            return Validation.CheckCloudEventArgument(cloudEvent, paramName);
         }
 
         private void PopulateAttributesFromStructuredEvent(CloudEvent cloudEvent, JObject jObject)
@@ -395,6 +402,19 @@ public override ReadOnlyMemory<byte> EncodeStructuredModeMessage(CloudEvent clou
             return stream.ToArray();
         }
 
+        /// <summary>
+        /// Converts the given <see cref="CloudEvent"/> to a <see cref="JObject"/> containing the structured mode JSON format representation
+        /// of the event.
+        /// </summary>
+        /// <param name="cloudEvent">The event to convert. Must not be null.</param>
+        /// <returns>A <see cref="JObject"/> containing the structured mode JSON format representation of the event.</returns>
+        public JObject ConvertToJObject(CloudEvent cloudEvent)
+        {
+            var writer = new JTokenWriter();
+            WriteCloudEventForBatchOrStructuredMode(writer, cloudEvent);
+            return (JObject) writer.Token!;
+        }
+
         /// <inheritdoc />
         public override ReadOnlyMemory<byte> EncodeBatchModeMessage(IEnumerable<CloudEvent> cloudEvents, out ContentType contentType)
         {

test/CloudNative.CloudEvents.UnitTests/NewtonsoftJson/JsonEventFormatterTest.cs

@@ -1092,6 +1092,55 @@ public void EncodeStructured_IndentationSettings()
             Assert.Equal(expected, json);
         }
 
+        // Effectively smoke tests for LINQ to JSON conversions; these piggy-back on the same implementation
+        // as the rest of the code, so we don't need to test exhaustively.
+
+        [Fact]
+        public void ConvertToJObject()
+        {
+            var cloudEvent = new CloudEvent
+            {
+                Data = SampleBinaryData
+            }.PopulateRequiredAttributes();
+
+            JObject obj = new JsonEventFormatter().ConvertToJObject(cloudEvent);
+            var asserter = new JTokenAsserter
+            {
+                { "data_base64", JTokenType.String, SampleBinaryDataBase64 },
+                { "id", JTokenType.String, "test-id" },
+                { "source", JTokenType.String, "//test" },
+                { "specversion", JTokenType.String, "1.0" },
+                { "type", JTokenType.String, "test-type" },
+            };
+            asserter.AssertProperties(obj, assertCount: true);
+        }
+
+        [Fact]
+        public void ConvertFromJObject()
+        {
+            var obj = new JObject
+            {
+                ["specversion"] = "1.0",
+                ["type"] = "test-type",
+                ["id"] = "test-id",
+                ["data"] = "text", // Just so that it's reasonable to have a DataContentType,
+                ["datacontenttype"] = "text/plain",
+                ["dataschema"] = "https://data-schema",
+                ["subject"] = "event-subject",
+                ["source"] = "//event-source",
+                ["time"] = SampleTimestampText
+            };
+            var cloudEvent = new JsonEventFormatter().ConvertFromJObject(obj, extensionAttributes: null);
+            Assert.Equal(CloudEventsSpecVersion.V1_0, cloudEvent.SpecVersion);
+            Assert.Equal("test-type", cloudEvent.Type);
+            Assert.Equal("test-id", cloudEvent.Id);
+            Assert.Equal("text/plain", cloudEvent.DataContentType);
+            Assert.Equal(new Uri("https://data-schema"), cloudEvent.DataSchema);
+            Assert.Equal("event-subject", cloudEvent.Subject);
+            Assert.Equal(new Uri("//event-source", UriKind.RelativeOrAbsolute), cloudEvent.Source);
+            AssertTimestampsEqual(SampleTimestamp, cloudEvent.Time);
+        }
+
         // Utility methods
         private static object? DecodeBinaryModeEventData(byte[] bytes, string contentType)
         {