Support nullable navigation property without navigation binding

src/Microsoft.OData.Core/IODataFeedAndEntryTypeContext.cs

@@ -27,6 +27,11 @@ internal interface IODataFeedAndEntryTypeContext
         /// </summary>
         string NavigationSourceEntityTypeName { get; }
 
+        /// <summary>
+        /// The full type name of the navigation source of the feed or entry.
+        /// </summary>
+        string NavigationSourceFullTypeName { get; }
+
         /// <summary>
         /// The kind of the navigation source of the feed or entry.
         /// </summary>

src/Microsoft.OData.Core/ODataContextUriBuilder.cs

@@ -39,8 +39,8 @@ internal sealed class ODataContextUriBuilder
             { ODataPayloadKind.IndividualProperty,      ValidateResourcePath },
             { ODataPayloadKind.Collection,              ValidateCollectionType },
             { ODataPayloadKind.Property,                ValidateType },
-            { ODataPayloadKind.Entry,                   ValidateNavigationPath },
-            { ODataPayloadKind.Feed,                    ValidateNavigationPath },
+            { ODataPayloadKind.Entry,                   ValidateNavigationSource },
+            { ODataPayloadKind.Feed,                    ValidateNavigationSource },
             { ODataPayloadKind.Delta,                   ValidateDelta },
         };
 
@@ -213,12 +213,12 @@ private static void ValidateCollectionType(ODataContextUrlInfo contextUrlInfo)
         }
 
         /// <summary>
-        /// Validate NavigationPath for given ODataContextUrlInfo for entry or feed
+        /// Validate NavigationSource for given ODataContextUrlInfo for entry or feed
         /// </summary>
         /// <param name="contextUrlInfo">The ODataContextUrlInfo to evaluate on.</param>
-        private static void ValidateNavigationPath(ODataContextUrlInfo contextUrlInfo)
+        private static void ValidateNavigationSource(ODataContextUrlInfo contextUrlInfo)
         {
-            if (string.IsNullOrEmpty(contextUrlInfo.NavigationPath))
+            if (string.IsNullOrEmpty(contextUrlInfo.NavigationSource))
             {
                 throw new ODataException(Strings.ODataContextUriBuilder_NavigationSourceMissingForEntryAndFeed);
             }

src/Microsoft.OData.Core/ODataContextUrlInfo.cs

@@ -26,6 +26,9 @@ internal sealed class ODataContextUrlInfo
         /// <summary>Whether target is contained</summary>
         private bool isContained;
 
+        /// <summary>Whether target is unknown entity set</summary>
+        private bool isUnknownEntitySet;
+
         /// <summary>The navigation soruce for current target</summary>
         private string navigationSource;
 
@@ -48,6 +51,14 @@ internal string NavigationPath
         {
             get
             {
+                if (this.isUnknownEntitySet)
+                {
+                    // If the navigation target is not specified, i.e., UnknownEntitySet,
+                    // the navigation path should be null so that type name will be used
+                    // to build the context Url.
+                    return null;
+                }
+
                 string navigationPath = null;
                 if (this.isContained && this.odataUri != null && this.odataUri.Path != null)
                 {
@@ -64,6 +75,12 @@ internal string NavigationPath
             }
         }
 
+        /// <summary>Name of the navigation source used for building context Url</summary>
+        internal string NavigationSource
+        {
+            get { return this.navigationSource; }
+        }
+
         /// <summary>ResourcePath used for building context Url</summary>
         internal string ResourcePath
         {
@@ -151,6 +168,7 @@ internal static ODataContextUrlInfo Create(IEdmNavigationSource navigationSource
             return new ODataContextUrlInfo()
             {
                 isContained = kind == EdmNavigationSourceKind.ContainedEntitySet,
+                isUnknownEntitySet = kind == EdmNavigationSourceKind.UnknownEntitySet,
                 navigationSource = navigationSource.Name,
                 TypeCast = navigationSourceEntityType == expectedEntityTypeName ? null : expectedEntityTypeName,
                 TypeName = navigationSourceEntityType,
@@ -173,9 +191,10 @@ internal static ODataContextUrlInfo Create(ODataFeedAndEntryTypeContext typeCont
             return new ODataContextUrlInfo()
                 {
                     isContained = typeContext.NavigationSourceKind == EdmNavigationSourceKind.ContainedEntitySet,
+                    isUnknownEntitySet = typeContext.NavigationSourceKind == EdmNavigationSourceKind.UnknownEntitySet,
                     navigationSource = typeContext.NavigationSourceName,
                     TypeCast = typeContext.NavigationSourceEntityTypeName == typeContext.ExpectedEntityTypeName ? null : typeContext.ExpectedEntityTypeName,
-                    TypeName = typeContext.NavigationSourceEntityTypeName,
+                    TypeName = typeContext.NavigationSourceFullTypeName,
                     IncludeFragmentItemSelector = isSingle && typeContext.NavigationSourceKind != EdmNavigationSourceKind.Singleton,
                     odataUri = odataUri
                 };
@@ -195,6 +214,7 @@ internal static ODataContextUrlInfo Create(ODataFeedAndEntryTypeContext typeCont
             ODataContextUrlInfo contextUriInfo = new ODataContextUrlInfo()
             {
                 isContained = typeContext.NavigationSourceKind == EdmNavigationSourceKind.ContainedEntitySet,
+                isUnknownEntitySet = typeContext.NavigationSourceKind == EdmNavigationSourceKind.UnknownEntitySet,
                 navigationSource = typeContext.NavigationSourceName,
                 TypeCast = typeContext.NavigationSourceEntityTypeName == typeContext.ExpectedEntityTypeName ? null : typeContext.ExpectedEntityTypeName,
                 TypeName = typeContext.NavigationSourceEntityTypeName,

src/Microsoft.OData.Core/ODataFeedAndEntryTypeContext.cs

@@ -51,6 +51,14 @@ public virtual string NavigationSourceEntityTypeName
             get { return this.ValidateAndReturn(default(string)); }
         }
 
+        /// <summary>
+        /// The full type name of the navigation source of the feed or entry.
+        /// </summary>
+        public virtual string NavigationSourceFullTypeName
+        {
+            get { return this.ValidateAndReturn(default(string)); }
+        }
+
         /// <summary>
         /// The kind of the navigation source of the feed or entry.
         /// </summary>
@@ -174,6 +182,25 @@ public override string NavigationSourceEntityTypeName
                 get { return this.serializationInfo.NavigationSourceEntityTypeName; }
             }
 
+            /// <summary>
+            /// The full type name of the navigation source of the feed or entry.
+            /// </summary>
+            public override string NavigationSourceFullTypeName
+            {
+                get
+                {
+                    if (this.IsFromCollection)
+                    {
+                        return EdmLibraryExtensions.GetCollectionTypeName(
+                            this.serializationInfo.NavigationSourceEntityTypeName);
+                    }
+                    else
+                    {
+                        return this.serializationInfo.NavigationSourceEntityTypeName;
+                    }
+                }
+            }
+
             /// <summary>
             /// The kind of the navigation source of the feed or entry.
             /// </summary>
@@ -299,6 +326,15 @@ internal ODataFeedAndEntryTypeContextWithModel(IEdmNavigationSource navigationSo
                     }
                 }
 
+                IEdmUnknownEntitySet unknownEntitySet = navigationSource as IEdmUnknownEntitySet;
+                if (unknownEntitySet != null)
+                {
+                    if (unknownEntitySet.Type.TypeKind == EdmTypeKind.Collection)
+                    {
+                        this.isFromCollection = true;
+                    }
+                }
+
                 this.navigationSourceName = this.navigationSource.Name;
                 this.isMediaLinkEntry = this.expectedEntityType.HasStream;
                 this.lazyUrlConvention = new SimpleLazy<UrlConvention>(() => UrlConvention.ForModel(this.model));
@@ -320,6 +356,14 @@ public override string NavigationSourceEntityTypeName
                 get { return this.navigationSourceEntityType.FullName(); }
             }
 
+            /// <summary>
+            /// The full type name of the navigation source of the feed or entry.
+            /// </summary>
+            public override string NavigationSourceFullTypeName
+            {
+                get { return this.navigationSource.Type.FullTypeName(); }
+            }
+
             /// <summary>
             /// The kind of the navigation source of the feed or entry.
             /// </summary>

src/Microsoft.OData.Core/UriParser/Parsers/ODataPathParser.cs

@@ -1190,8 +1190,16 @@ private void CreatePropertySegment(ODataPathSegment previous, IEdmProperty prope
                 var navigationProperty = (IEdmNavigationProperty)property;
                 IEdmNavigationSource navigationSource = previous.TargetEdmNavigationSource.FindNavigationTarget(navigationProperty);
 
-                // If we can't compute the target navigation source, then throw
-                if (navigationSource is IEdmUnknownEntitySet)
+                // Relationship between TargetMultiplicity and navigation property:
+                //  1) EdmMultiplicity.Many <=> collection navigation property
+                //  2) EdmMultiplicity.ZeroOrOne <=> nullable singleton navigation property
+                //  3) EdmMultiplicity.One <=> non-nullable singleton navigation property
+                //
+                // According to OData Spec CSDL 7.1.3:
+                //  1) non-nullable singleton navigation property => navigation source required
+                //  2) the other cases => navigation source optional
+                if (navigationProperty.TargetMultiplicity() == EdmMultiplicity.One
+                    && navigationSource is IEdmUnknownEntitySet)
                 {
                     // Specifically not throwing ODataUriParserException since it's more an an internal server error
                     throw new ODataException(ODataErrorStrings.RequestUriProcessor_TargetEntitySetNotFound(property.Name));

src/Microsoft.OData.Edm/ExtensionMethods/ExtensionMethods.cs

@@ -2253,6 +2253,14 @@ public static IEdmEntityType EntityType(this IEdmNavigationSource navigationSour
                     return collectionType.ElementType.Definition as IEdmEntityType;
                 }
 
+                var unknownEntitySet = entitySetBase as IEdmUnknownEntitySet;
+                if (unknownEntitySet != null)
+                {
+                    // Handle missing navigation target for nullable
+                    // singleton navigation property.
+                    return unknownEntitySet.Type as IEdmEntityType;
+                }
+
                 return null;
             }
 

src/Microsoft.OData.Edm/Library/EdmUnknownEntitySet.cs

@@ -42,6 +42,14 @@ public override IEdmPathExpression Path
             get { return this.path ?? (this.path = ComputePath()); }
         }
 
+        /// <summary>
+        /// Gets the type of this navigation source.
+        /// </summary>
+        public override IEdmType Type
+        {
+            get { return this.navigationProperty.Type.Definition; }
+        }
+
         /// <summary>
         /// Finds the entity set that a navigation property targets.
         /// </summary>

test/FunctionalTests/Tests/DataOData/Tests/OData.Query.TDD.Tests/Semantic/Functional/PathFunctionalTests.cs

@@ -584,18 +584,31 @@ public void NavigationPropertyOnEntity()
             path.NavigationSource().Should().Be(HardCodedTestModel.GetDogsSet());
         }
 
-        // TODO： everywhere we call FindNavigationTarget() use a helper and throw the right exception
         [TestMethod]
         public void NavigationPropertyWithMissingEntitySetShouldThrow()
         {
-            var model = ModelBuildingHelpers.GetModelWithNavPropWithNoTargetSet();
+            var model = ModelBuildingHelpers.GetTestModelForNavigationPropertyBinding();
+            var path = new ODataUriParser(model, new Uri("http://gobbldygook/"), new Uri("http://gobbldygook/Vegetables(1)/GenesModified")).ParsePath();
+            Assert.AreEqual(path.LastSegment.Identifier, "GenesModified");
+        }
 
-            // We want a descriptive error message, and do NOT want a ODataUriParserException so the service implementor does not blindly surface this to users
-            Action parse = () => new ODataUriParser(model, new Uri("http://gobbldygook/"), new Uri("http://gobbldygook/Vegetables(1)/GenesModified")).ParsePath();
-            parse.ShouldThrow<ODataException>().WithMessage("The target Entity Set of Navigation Property 'GenesModified' could not be found. This is most likely an error in the IEdmModel.").
+        [TestMethod]
+        public void SingletonNonNullableNavigationPropertyWithMissingEntitySetShouldThrow()
+        {
+            var model = ModelBuildingHelpers.GetTestModelForNavigationPropertyBinding();
+            Action parse = () => new ODataUriParser(model, new Uri("http://gobbldygook/"), new Uri("http://gobbldygook/Vegetables(1)/KeyGene")).ParsePath();
+            parse.ShouldThrow<ODataException>().WithMessage("The target Entity Set of Navigation Property 'KeyGene' could not be found. This is most likely an error in the IEdmModel.").
                 And.GetType().Should().Be<ODataException>();
         }
 
+        [TestMethod]
+        public void SingletonNullableNavigationPropertyWithMissingEntitySetShouldNotThrow()
+        {
+            var model = ModelBuildingHelpers.GetTestModelForNavigationPropertyBinding();
+            var path = new ODataUriParser(model, new Uri("http://gobbldygook/"), new Uri("http://gobbldygook/Vegetables(1)/DefectiveGene")).ParsePath();
+            Assert.AreEqual(path.LastSegment.Identifier, "DefectiveGene");
+        }
+
         [TestMethod]
         public void ActionImportWithNoReturnEntitySet()
         {

test/FunctionalTests/Tests/DataOData/Tests/OData.Query.TDD.Tests/TestUtilities/ModelBuildingHelpers.cs

@@ -93,14 +93,19 @@ public static IEdmType BuildValidComplexType()
             return new EdmComplexType("Name.Space", "ComplexType");
         }
 
-        public static EdmModel GetModelWithNavPropWithNoTargetSet()
+        public static EdmModel GetTestModelForNavigationPropertyBinding()
         {
-            // Create a model with a Navigation Property with a missing target entity set
+            // Create a model with three navigation properties:
+            // 2. "Many" with no target entity set
+            // 4. "ZeroOrOne" with no target entity set
+            // 6. "One" with no target entity set
             EdmEntityType geneType = new EdmEntityType("Test", "Gene");
             EdmEntityType vegetableType = new EdmEntityType("Test", "Vegetable");
             IEdmStructuralProperty id = vegetableType.AddStructuralProperty("ID", EdmCoreModel.Instance.GetInt32(false));
             vegetableType.AddKeys(id);
-            vegetableType.AddUnidirectionalNavigation(new EdmNavigationPropertyInfo() {Name = "GenesModified", Target = geneType, TargetMultiplicity = EdmMultiplicity.Many,});
+            vegetableType.AddUnidirectionalNavigation(new EdmNavigationPropertyInfo { Name = "GenesModified", Target = geneType, TargetMultiplicity = EdmMultiplicity.Many });
+            vegetableType.AddUnidirectionalNavigation(new EdmNavigationPropertyInfo { Name = "DefectiveGene", Target = geneType, TargetMultiplicity = EdmMultiplicity.ZeroOrOne });
+            vegetableType.AddUnidirectionalNavigation(new EdmNavigationPropertyInfo { Name = "KeyGene", Target = geneType, TargetMultiplicity = EdmMultiplicity.One });
 
             // Note how we do NOT call AddNavigationTarget(...) to create associations 
             EdmEntityContainer container = new EdmEntityContainer("Test", "Container");

test/FunctionalTests/Tests/DataOData/Tests/OData.TDD.Tests/Evaluation/ODataConventionalEntityMetadataBuilderTests.cs

@@ -1197,6 +1197,8 @@ internal class TestFeedAndEntryTypeContext : IODataFeedAndEntryTypeContext
 
         public string NavigationSourceEntityTypeName { get; set; }
 
+        public string NavigationSourceFullTypeName { get; set; }
+
         public string ExpectedEntityTypeName { get; set; }
 
         public bool IsMediaLinkEntry { get; set; }

test/FunctionalTests/Tests/DataOData/Tests/OData.TDD.Tests/Microsoft.Test.OData.TDD.Tests.csproj

@@ -144,6 +144,7 @@
     <Compile Include="BinaryValueEncodingTests.cs" />
     <Compile Include="ContextUrlWriterReaderTests.cs" />
     <Compile Include="Writer\FullPayloadValidateTests.cs" />
+    <Compile Include="Writer\JsonLight\ODataJsonLightFeedWriterTests.cs" />
     <Compile Include="Writer\JsonLight\ODataJsonLightDeltaWriterTests.cs" />
     <Compile Include="Writer\JsonLight\ODataJsonLightInheritComplexCollectionWriterTests.cs" />
     <Compile Include="Writer\JsonLight\ODataJsonLightODataTypeSerializerTests.cs" />