JSON formatter container conversions

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)
         {

src/CloudNative.CloudEvents.SystemTextJson/JsonEventFormatter.cs

@@ -10,6 +10,7 @@
 using System.Text;
 using System.Text.Json;
 using System.Threading.Tasks;
+using System.Xml.Linq;
 
 namespace CloudNative.CloudEvents.SystemTextJson
 {
@@ -157,6 +158,15 @@ public override IReadOnlyList<CloudEvent> DecodeBatchModeMessage(Stream body, Co
         public override IReadOnlyList<CloudEvent> DecodeBatchModeMessage(ReadOnlyMemory<byte> body, ContentType? contentType, IEnumerable<CloudEventAttribute>? extensionAttributes) =>
             DecodeBatchModeMessageImpl(BinaryDataUtilities.AsStream(body), contentType, extensionAttributes, false).GetAwaiter().GetResult();
 
+        /// <summary>
+        /// Converts the given <see cref="JsonElement"/> into a <see cref="CloudEvent"/>.
+        /// </summary>
+        /// <param name="element">The JSON representation of a CloudEvent. Must have a <see cref="JsonElement.ValueKind"/> of <see cref="JsonValueKind.Object"/>.</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 ConvertFromJsonElement(JsonElement element, IEnumerable<CloudEventAttribute>? extensionAttributes) =>
+            DecodeJsonElement(element, extensionAttributes, nameof(element));
+
         private async Task<IReadOnlyList<CloudEvent>> DecodeBatchModeMessageImpl(Stream data, ContentType? contentType, IEnumerable<CloudEventAttribute>? extensionAttributes, bool async)
         {
             Validation.CheckNotNull(data, nameof(data));
@@ -428,6 +438,27 @@ public override ReadOnlyMemory<byte> EncodeStructuredModeMessage(CloudEvent clou
             return stream.ToArray();
         }
 
+        /// <summary>
+        /// Converts the given <see cref="CloudEvent"/> to a <see cref="JsonElement"/> containing the structured mode JSON format representation
+        /// of the event.
+        /// </summary>
+        /// <remarks>The current implementation of this method is inefficient. Care should be taken before
+        /// using this in performance-sensitive scenarios. The efficiency may well be improved in the future.</remarks>
+        /// <param name="cloudEvent">The event to convert. Must not be null.</param>
+        /// <returns>A <see cref="JsonElement"/> containing the structured mode JSON format representation of the event.</returns>
+        public JsonElement ConvertToJsonElement(CloudEvent cloudEvent)
+        {
+            // Unfortunately System.Text.Json doesn't have an equivalent of JTokenWriter,
+            // so we serialize all the data then parse it. That's horrible, but at least
+            // it's contained in this one place (rather than in user code everywhere else).
+            // We can optimize it later by duplicating the logic of WriteCloudEventForBatchOrStructuredMode
+            // to use System.Text.Json.Nodes.
+            var data = EncodeStructuredModeMessage(cloudEvent, out _);
+            using var document = JsonDocument.Parse(data);
+            // We have to clone the data so that we can dispose of the JsonDocument.
+            return document.RootElement.Clone();
+        }
+
         private Utf8JsonWriter CreateUtf8JsonWriter(Stream stream)
         {
             var options = new JsonWriterOptions

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)
         {

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

@@ -2,6 +2,7 @@
 // Licensed under the Apache 2.0 license.
 // See LICENSE file in the project root for full license information.
 
+using CloudNative.CloudEvents.Core;
 using CloudNative.CloudEvents.UnitTests;
 using System;
 using System.Collections.Generic;
@@ -15,10 +16,9 @@
 using System.Threading.Tasks;
 using Xunit;
 using static CloudNative.CloudEvents.UnitTests.TestHelpers;
+using JArray = Newtonsoft.Json.Linq.JArray;
 // JObject is a really handy way of creating JSON which we can then parse with System.Text.Json
 using JObject = Newtonsoft.Json.Linq.JObject;
-using JArray = Newtonsoft.Json.Linq.JArray;
-using CloudNative.CloudEvents.Core;
 
 namespace CloudNative.CloudEvents.SystemTextJson.UnitTests
 {
@@ -1102,6 +1102,53 @@ public void EncodeStructured_IndentationSettings()
             Assert.Equal(expected, json);
         }
 
+        [Fact]
+        public void ConvertToJsonElement()
+        {
+            var cloudEvent = new CloudEvent
+            {
+                Data = SampleBinaryData
+            }.PopulateRequiredAttributes();
+
+            JsonElement element = new JsonEventFormatter().ConvertToJsonElement(cloudEvent);
+            var asserter = new JsonElementAsserter
+            {
+                { "data_base64", JsonValueKind.String, SampleBinaryDataBase64 },
+                { "id", JsonValueKind.String, "test-id" },
+                { "source", JsonValueKind.String, "//test" },
+                { "specversion", JsonValueKind.String, "1.0" },
+                { "type", JsonValueKind.String, "test-type" }
+            };
+            asserter.AssertProperties(element, assertCount: true);
+        }
+
+        [Fact]
+        public void ConvertFromJsonElement()
+        {
+            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
+            };
+            using var document = JsonDocument.Parse(obj.ToString());
+            var cloudEvent = new JsonEventFormatter().ConvertFromJsonElement(document.RootElement, 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)
         {