Fixes #3154: Enable serialize/deserialize navigation property with count without content

src/Microsoft.OData.Core/Json/ODataJsonResourceDeserializer.cs

@@ -1111,6 +1111,17 @@ in resourceState.PropertyAndAnnotationCollector.GetODataPropertyAnnotations(nest
                         nestedResourceInfo.TypeAnnotation = new ODataTypeAnnotation((string)propertyAnnotation.Value);
                         break;
 
+                    case ODataAnnotationNames.ODataCount:
+                        Debug.Assert(propertyAnnotation.Value is long && propertyAnnotation.Value != null, "The odata.count annotation should have been parsed as a non-null long.");
+                        nestedResourceInfo.Count = (long?)propertyAnnotation.Value;
+                        break;
+
+                    // TODO: do we support odata.context uri here? why?
+                    case ODataAnnotationNames.ODataContext:
+                        Debug.Assert(propertyAnnotation.Value is Uri && propertyAnnotation.Value != null, "The odata.context annotation should have been parsed as a non-null Uri.");
+                        nestedResourceInfo.ContextUrl = (Uri)propertyAnnotation.Value;
+                        break;
+
                     default:
                         throw new ODataException(Error.Format(SRResources.ODataJsonResourceDeserializer_UnexpectedDeferredLinkPropertyAnnotation, nestedResourceInfo.Name, propertyAnnotation.Key));
                 }

src/Microsoft.OData.Core/Json/ODataJsonResourceSerializer.cs

@@ -208,7 +208,7 @@ internal void WriteResourceEndMetadataProperties(IODataJsonWriterResourceState r
                 Debug.Assert(resource.MetadataBuilder != null, "resource.MetadataBuilder != null");
                 navigationLinkInfo.NestedResourceInfo.MetadataBuilder = resource.MetadataBuilder;
 
-                this.WriteNavigationLinkMetadata(navigationLinkInfo.NestedResourceInfo, duplicatePropertyNameChecker);
+                this.WriteNavigationLinkMetadata(navigationLinkInfo.NestedResourceInfo, duplicatePropertyNameChecker, count: false);
                 navigationLinkInfo = resource.MetadataBuilder.GetNextUnprocessedNavigationLink();
             }
 
@@ -240,7 +240,8 @@ internal void WriteResourceEndMetadataProperties(IODataJsonWriterResourceState r
         /// </summary>
         /// <param name="nestedResourceInfo">The navigation link to write the metadata for.</param>
         /// <param name="duplicatePropertyNameChecker">The DuplicatePropertyNameChecker to use.</param>
-        internal void WriteNavigationLinkMetadata(ODataNestedResourceInfo nestedResourceInfo, IDuplicatePropertyNameChecker duplicatePropertyNameChecker)
+        /// <param name="count">The boolean value indicating to write the count value if has.</param>
+        internal void WriteNavigationLinkMetadata(ODataNestedResourceInfo nestedResourceInfo, IDuplicatePropertyNameChecker duplicatePropertyNameChecker, bool count = false)
         {
             Debug.Assert(nestedResourceInfo != null, "nestedResourceInfo != null");
             Debug.Assert(!string.IsNullOrEmpty(nestedResourceInfo.Name), "The nested resource info Name should have been validated by now.");
@@ -261,6 +262,12 @@ internal void WriteNavigationLinkMetadata(ODataNestedResourceInfo nestedResource
                 this.ODataAnnotationWriter.WritePropertyAnnotationName(navigationLinkName, ODataAnnotationNames.ODataNavigationLinkUrl);
                 this.JsonWriter.WriteValue(this.UriToString(navigationLinkUrl));
             }
+
+            if (count && nestedResourceInfo.Count != null)
+            {
+                this.ODataAnnotationWriter.WritePropertyAnnotationName(navigationLinkName, ODataAnnotationNames.ODataCount);
+                this.JsonWriter.WriteValue(nestedResourceInfo.Count.Value);
+            }
         }
 
         /// <summary>
@@ -567,8 +574,9 @@ await this.WriteOperationsAsync(functions.Cast<ODataOperation>(), /*isAction*/ f
         /// </summary>
         /// <param name="nestedResourceInfo">The navigation link to write the metadata for.</param>
         /// <param name="duplicatePropertyNameChecker">The DuplicatePropertyNameChecker to use.</param>
+        /// <param name="count">he boolean value indicating to write the count value if has.</param>
         /// <returns>A task that represents the asynchronous write operation.</returns>
-        internal async Task WriteNavigationLinkMetadataAsync(ODataNestedResourceInfo nestedResourceInfo, IDuplicatePropertyNameChecker duplicatePropertyNameChecker)
+        internal async Task WriteNavigationLinkMetadataAsync(ODataNestedResourceInfo nestedResourceInfo, IDuplicatePropertyNameChecker duplicatePropertyNameChecker, bool count = false)
         {
             Debug.Assert(nestedResourceInfo != null, "nestedResourceInfo != null");
             Debug.Assert(!string.IsNullOrEmpty(nestedResourceInfo.Name), "The nested resource info Name should have been validated by now.");
@@ -592,6 +600,12 @@ await this.ODataAnnotationWriter.WritePropertyAnnotationNameAsync(navigationLink
                 await this.JsonWriter.WriteValueAsync(this.UriToString(navigationLinkUrl))
                     .ConfigureAwait(false);
             }
+
+            if (count && nestedResourceInfo.Count.HasValue)
+            {
+                await this.ODataAnnotationWriter.WritePropertyAnnotationNameAsync(navigationLinkName, ODataAnnotationNames.ODataCount).ConfigureAwait(false);
+                await this.JsonWriter.WriteValueAsync(nestedResourceInfo.Count.Value).ConfigureAwait(false);
+            }
         }
 
         /// <summary>

src/Microsoft.OData.Core/Json/ODataJsonWriter.cs

@@ -968,7 +968,7 @@ protected override void WriteDeferredNestedResourceInfo(ODataNestedResourceInfo
             Debug.Assert(this.writingResponse, "Deferred links are only supported in response, we should have verified this already.");
 
             // A deferred nested resource info is just the link metadata, no value.
-            this.jsonResourceSerializer.WriteNavigationLinkMetadata(nestedResourceInfo, this.DuplicatePropertyNameChecker);
+            this.jsonResourceSerializer.WriteNavigationLinkMetadata(nestedResourceInfo, this.DuplicatePropertyNameChecker, count: true);
         }
 
         /// <summary>
@@ -999,7 +999,7 @@ protected override void StartNestedResourceInfoWithContent(ODataNestedResourceIn
                 }
 
                 // Write the nested resource info metadata first. The rest is written by the content resource or resource set.
-                this.jsonResourceSerializer.WriteNavigationLinkMetadata(nestedResourceInfo, this.DuplicatePropertyNameChecker);
+                this.jsonResourceSerializer.WriteNavigationLinkMetadata(nestedResourceInfo, this.DuplicatePropertyNameChecker, count: false);
             }
             else
             {
@@ -2038,7 +2038,7 @@ protected override Task WriteDeferredNestedResourceInfoAsync(ODataNestedResource
             // A deferred nested resource info is just the link metadata, no value.
             return this.jsonResourceSerializer.WriteNavigationLinkMetadataAsync(
                 nestedResourceInfo,
-                this.DuplicatePropertyNameChecker);
+                this.DuplicatePropertyNameChecker, count: true);
         }
 
         /// <summary>
@@ -2078,7 +2078,7 @@ await this.jsonResourceSerializer.WriteNestedResourceInfoContextUrlAsync(innerNe
                     // Write the nested resource info metadata first. The rest is written by the content resource or resource set.
                     await this.jsonResourceSerializer.WriteNavigationLinkMetadataAsync(
                         innerNestedResourceInfo,
-                        this.DuplicatePropertyNameChecker).ConfigureAwait(false);
+                        this.DuplicatePropertyNameChecker, count: false).ConfigureAwait(false);
                 }
             }
             else

src/Microsoft.OData.Core/ODataNestedResourceInfo.cs

@@ -49,6 +49,17 @@ public string Name
             set;
         }
 
+        /// <summary>Gets or sets the number of items for this nested resource info.
+        /// Be noted, this count property is for nested resource info without content.
+        /// For nested resource info with content, please specify the count on ODataResourceSetBase.Count.
+        /// </summary>
+        /// <returns>The number of items in the resource set.</returns>
+        public long? Count
+        {
+            get;
+            set;
+        }
+
         /// <summary>Gets or sets the URI representing the Unified Resource Locator (URL) of the link.</summary>
         /// <returns>The URI representing the Unified Resource Locator (URL) of the link.</returns>
         public Uri Url

test/FunctionalTests/Microsoft.OData.Core.Tests/Json/ODataJsonEntryAndFeedSerializerTests.cs

@@ -51,6 +51,21 @@ public void SerializedNavigationPropertyShouldIncludeNavigationLinkUrl()
             Assert.Contains("[email protected]\":\"http://example.com/navigation", jsonResult);
         }
 
+        [Fact]
+        public void SerializedNavigationPropertyShouldIncludeCountIfApply()
+        {
+            var jsonResult = this.SerializeJsonFragment(serializer =>
+                serializer.WriteNavigationLinkMetadata(
+                    new ODataNestedResourceInfo
+                    {
+                        Name = "NavigationProperty",
+                        Count = 42
+                    },
+                    new DuplicatePropertyNameChecker(), true));
+
+            Assert.Contains("[email protected]\":42", jsonResult);
+        }
+
         [Fact]
         public void WriteOperationsOnRequestsShouldThrow()
         {

test/FunctionalTests/Microsoft.OData.Core.Tests/Json/ODataJsonResourceSerializerTests.cs

@@ -311,6 +311,27 @@ public async Task WriteNavigationLinkMetadataAsync_WritesNavigationLinkMetadata(
                 "\"[email protected]\":\"http://tempuri.org/Categories(1)/BestSeller\"", result);
         }
 
+        [Fact]
+        public async Task WriteNavigationLinkMetadataAsync_WritesCountMetadata()
+        {
+            var nestedResourceInfo = new ODataNestedResourceInfo
+            {
+                Name = "BestSeller",
+                IsCollection = true,
+                Count = 42
+            };
+
+            var result = await SetupJsonResourceSerializerAndRunTestAsync(
+                (jsonResourceSerializer) =>
+                {
+                    return jsonResourceSerializer.WriteNavigationLinkMetadataAsync(
+                        nestedResourceInfo,
+                        new NullDuplicatePropertyNameChecker(), true);
+                });
+
+            Assert.Equal("{\"[email protected]\":42", result);
+        }
+
         [Fact]
         public async Task WriteNestedResourceInfoContextUrlAsync_WritesNestedResourceInfoContextUrl()
         {

test/FunctionalTests/Microsoft.OData.Core.Tests/ScenarioTests/Writer/Json/FullPayloadValidateTests.cs

@@ -842,6 +842,33 @@ public void WritingNestedInlinecountTest()
                                                     "\"[email protected]\":\"http://example.org/odata.svc/navigation\"," +
                                                     "\"[email protected]\":1," +
                                                     "\"ContainedCollectionNavProp\":[]" +
+                                               "}" +
+                                            "]" +
+                                        "}";
+            Assert.Equal(expectedPayload, result);
+        }
+
+        [Fact]
+        public void WritingNestedInlinecountWithoutContentTest()
+        {
+            this.containedCollectionNavLink.Count = 42;
+            ODataItem[] itemsToWrite = new ODataItem[]
+            {
+                new ODataResourceSet(),
+                this.entryWithOnlyData1,
+                this.containedCollectionNavLink
+            };
+
+            string resourcePath = "EntitySet";
+            string result = this.GetWriterOutputForContentTypeAndKnobValue("application/json;odata.metadata=minimal", true, itemsToWrite, Model, EntitySet, EntityType, null, null, resourcePath);
+
+            string expectedPayload = "{" +
+                                            "\"@odata.context\":\"http://example.org/odata.svc/$metadata#EntitySet\"," +
+                                            "\"value\":[" +
+                                                "{" +
+                                                    "\"ID\":101,\"Name\":\"Alice\"," +
+                                                    "\"[email protected]\":\"http://example.org/odata.svc/navigation\"," +
+                                                    "\"[email protected]\":42" +
                                                 "}" +
                                             "]" +
                                         "}";
@@ -922,6 +949,50 @@ public void ReadingNestedInlinecountTest()
             ODataResourceSet topFeed = feedList[1];
             Assert.Null(topFeed.Count);
         }
+
+        [Fact]
+        public void ReadingNestedInlinecountWithoutContentTest()
+        {
+            string payload = "{" +
+                                "\"@odata.context\":\"http://example.org/odata.svc/$metadata#EntitySet\"," +
+                                "\"value\":[" +
+                                    "{" +
+                                        "\"ID\":101,\"Name\":\"Alice\"," +
+                                        "\"[email protected]\":\"http://example.org/odata.svc/$metadata#EntitySet(101)/ContainedCollectionNavProp\"," +
+                                        "\"[email protected]\":\"http://example.org/odata.svc/navigation\"," +
+                                        "\"[email protected]\":51" +
+                                    "}" +
+                                "]" +
+                            "}";
+            InMemoryMessage message = new InMemoryMessage();
+            message.SetHeader("Content-Type", "application/json;odata.metadata=minimal");
+            message.Stream = new MemoryStream(Encoding.UTF8.GetBytes(payload));
+            List<ODataResourceSet> feedList = new List<ODataResourceSet>();
+
+            ODataNestedResourceInfo nestedResourceInfo = null;
+            using (var messageReader = new ODataMessageReader((IODataResponseMessage)message, null, Model))
+            {
+                var reader = messageReader.CreateODataResourceSetReader();
+                while (reader.Read())
+                {
+                    switch (reader.State)
+                    {
+                        case ODataReaderState.ResourceSetEnd:
+                            feedList.Add(reader.Item as ODataResourceSet);
+                            break;
+
+                        case ODataReaderState.NestedResourceInfoStart:
+                            nestedResourceInfo = reader.Item as ODataNestedResourceInfo;
+                            break;
+
+                    }
+                }
+            }
+
+            Assert.Single(feedList); // only contains the toplevel
+            Assert.NotNull(nestedResourceInfo);
+            Assert.Equal(51, nestedResourceInfo.Count);
+        }
         #endregion Inlinecount Tests
 
         [Fact]