Fixed: Nullable properties will no longer lead to errors in the sorti…

…ng middleware (#1419)

src/Core/Types.Sorting.Tests/QueryableSortVisitorTests.cs

@@ -148,6 +148,72 @@ public void Sort_NoSortSpecified_ShouldReturnUnalteredSource()
             );
         }
 
+        [Fact]
+        public void Sort_Nullable_ShouldSortNullableProperlyAsc()
+        {
+            // arrange 
+            var value = new ObjectValueNode(
+                new ObjectFieldNode("nullableInt",
+                    new EnumValueNode(SortOperationKind.Asc)
+                    )
+            );
+
+            FooSortType sortType = CreateType(new FooSortType());
+
+            IQueryable<Foo> a = new[]
+            {
+                new Foo {Bar = "b"},
+                new Foo {Bar = "c", NullableInt = 2},
+                new Foo {Bar = "a", NullableInt = 1}
+            }.AsQueryable();
+
+            // act
+            var filter = new QueryableSortVisitor(
+                sortType, typeof(Foo));
+            value.Accept(filter);
+            IQueryable<Foo> aFiltered = filter.Sort(a);
+
+            // assert 
+            Assert.Collection(aFiltered,
+                foo => Assert.Equal("b", foo.Bar),
+                foo => Assert.Equal("a", foo.Bar),
+                foo => Assert.Equal("c", foo.Bar)
+            );
+        }
+
+        [Fact]
+        public void Sort_Nullable_ShouldSortNullableProperlyDesc()
+        {
+            // arrange 
+            var value = new ObjectValueNode(
+                new ObjectFieldNode("nullableInt",
+                    new EnumValueNode(SortOperationKind.Desc)
+                    )
+            );
+
+            FooSortType sortType = CreateType(new FooSortType());
+
+            IQueryable<Foo> a = new[]
+            {
+                new Foo {Bar = "b"},
+                new Foo {Bar = "c", NullableInt = 2},
+                new Foo {Bar = "a", NullableInt = 1}
+            }.AsQueryable();
+
+            // act
+            var filter = new QueryableSortVisitor(
+                sortType, typeof(Foo));
+            value.Accept(filter);
+            IQueryable<Foo> aFiltered = filter.Sort(a);
+
+            // assert 
+            Assert.Collection(aFiltered,
+                foo => Assert.Equal("c", foo.Bar),
+                foo => Assert.Equal("a", foo.Bar),
+                foo => Assert.Equal("b", foo.Bar)
+            );
+        }
+
         public class FooSortType
             : SortInputType<Foo>
         {
@@ -160,6 +226,7 @@ protected override void Configure(
 
         public class Foo
         {
+            public int? NullableInt { get; set; }
             public string Bar { get; set; }
             public string Baz { get; set; }
         }

src/Core/Types.Sorting.Tests/SortInputTypeTests.cs

@@ -272,6 +272,7 @@ private class FooDirective { }
 
         private class Foo
         {
+            public bool? NullableBoolean { get; set; }
             public string Bar { get; set; }
             public string Baz { get; set; }
         }

src/Core/Types.Sorting.Tests/Types.Sorting.Tests.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk" ToolsVersion="Current">
+<Project Sdk="Microsoft.NET.Sdk" ToolsVersion="Current">
   <PropertyGroup>
     <TargetFramework>netcoreapp2.0</TargetFramework>
     <ChilliCurrentDirectory>$(MSBuildThisFileDirectory.TrimEnd('\').TrimEnd('/'))</ChilliCurrentDirectory>

src/Core/Types.Sorting.Tests/__snapshots__/SortInputTypeTests.Create_Implicit_Sorting.snap

@@ -9,6 +9,7 @@ type Query {
 input FooSort {
   bar: SortOperationKind
   baz: SortOperationKind
+  nullableBoolean: SortOperationKind
 }
 
 enum SortOperationKind {

src/Core/Types.Sorting.Tests/__snapshots__/SortInputTypeTests.Create_Implicit_Sorting_NoBindInvocation.snap

@@ -9,6 +9,7 @@ type Query {
 input FooSort {
   bar: SortOperationKind
   baz: SortOperationKind
+  nullableBoolean: SortOperationKind
 }
 
 enum SortOperationKind {

src/Core/Types.Sorting.Tests/__snapshots__/SortInputTypeTests.Create_Implicit_Sorting_WithIgnoredField.snap

@@ -8,6 +8,7 @@ type Query {
 
 input FooSort {
   bar: SortOperationKind
+  nullableBoolean: SortOperationKind
 }
 
 enum SortOperationKind {

src/Core/Types.Sorting.Tests/__snapshots__/SortInputTypeTests.Create_Implicit_Sorting_WithRenamedField.snap

@@ -8,6 +8,7 @@ type Query {
 
 input FooSort {
   bar: SortOperationKind
+  nullableBoolean: SortOperationKind
   quux: SortOperationKind
 }
 

src/Core/Types.Sorting.Tests/__snapshots__/SortInputTypeTests.SortInputType_AddDescription.snap

@@ -10,6 +10,7 @@ type Query {
 input FooSort {
   bar: SortOperationKind
   baz: SortOperationKind
+  nullableBoolean: SortOperationKind
 }
 
 enum SortOperationKind {

src/Core/Types.Sorting.Tests/__snapshots__/SortInputTypeTests.SortInputType_AddDirectives_DirectiveClassInstance.snap

@@ -9,6 +9,7 @@ type Query {
 input FooSort @foo {
   bar: SortOperationKind
   baz: SortOperationKind
+  nullableBoolean: SortOperationKind
 }
 
 enum SortOperationKind {

src/Core/Types.Sorting.Tests/__snapshots__/SortInputTypeTests.SortInputType_AddDirectives_DirectiveNode.snap

@@ -9,6 +9,7 @@ type Query {
 input FooSort @foo {
   bar: SortOperationKind
   baz: SortOperationKind
+  nullableBoolean: SortOperationKind
 }
 
 enum SortOperationKind {

src/Core/Types.Sorting.Tests/__snapshots__/SortInputTypeTests.SortInputType_AddDirectives_DirectiveType.snap

@@ -9,6 +9,7 @@ type Query {
 input FooSort @foo {
   bar: SortOperationKind
   baz: SortOperationKind
+  nullableBoolean: SortOperationKind
 }
 
 enum SortOperationKind {

src/Core/Types.Sorting.Tests/__snapshots__/SortInputTypeTests.SortInputType_AddDirectives_NameArgs.snap

@@ -9,6 +9,7 @@ type Query {
 input FooSort @foo {
   bar: SortOperationKind
   baz: SortOperationKind
+  nullableBoolean: SortOperationKind
 }
 
 enum SortOperationKind {

src/Core/Types.Sorting.Tests/__snapshots__/SortInputTypeTests.SortInputType_AddDirectives_NameArgs2.snap

@@ -9,6 +9,7 @@ type Query {
 input FooSort @foo {
   bar: SortOperationKind
   baz: SortOperationKind
+  nullableBoolean: SortOperationKind
 }
 
 enum SortOperationKind {

src/Core/Types.Sorting.Tests/__snapshots__/SortInputTypeTests.SortInputType_AddName.snap

@@ -9,6 +9,7 @@ type Query {
 input Test {
   bar: SortOperationKind
   baz: SortOperationKind
+  nullableBoolean: SortOperationKind
 }
 
 enum SortOperationKind {

src/Core/Types.Sorting.Tests/__snapshots__/SortInputTypeTests.SortInputType_DynamicName.snap

@@ -9,6 +9,7 @@ type Query {
 input StringFoo {
   bar: SortOperationKind
   baz: SortOperationKind
+  nullableBoolean: SortOperationKind
 }
 
 enum SortOperationKind {

src/Core/Types.Sorting.Tests/__snapshots__/SortInputTypeTests.SortInputType_DynamicName_NonGeneric.snap

@@ -9,6 +9,7 @@ type Query {
 input StringFoo {
   bar: SortOperationKind
   baz: SortOperationKind
+  nullableBoolean: SortOperationKind
 }
 
 enum SortOperationKind {

src/Core/Types.Sorting/SortInputTypeDescriptor.cs

@@ -165,7 +165,15 @@ private bool TryCreateImplicitSorting(
             PropertyInfo property,
             out SortFieldDefinition definition)
         {
-            if (typeof(IComparable).IsAssignableFrom(property.PropertyType))
+            Type type = property.PropertyType;
+
+            if (type.IsGenericType
+                && System.Nullable.GetUnderlyingType(type) is Type nullableType)
+            {
+                type = nullableType;
+            }
+
+            if (typeof(IComparable).IsAssignableFrom(type))
             {
                 var field = new SortFieldDescriptor(Context, property);
                 definition = field.CreateDefinition();