fix(Selection): fix nullable relation (#1651)

ChilliCream · Apr 6, 2020 · e2e8957 · e2e8957
1 parent 6d4f771
commit e2e8957
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Showing 3 changed files with 62 additions and 4 deletions.
diff --git a/src/Core/Types.Selection.Abstractions.Tests/SelectionTestsBase.cs b/src/Core/Types.Selection.Abstractions.Tests/SelectionTestsBase.cs
@@ -771,6 +771,50 @@ public virtual void Execute_Selection_ObjectDeep()
                 });
         }
 
+        [Fact]
+        public virtual void Execute_Selection_ObjectDeepNull()
+        {
+            // arrange
+            IServiceCollection services;
+            Func<IResolverContext, IEnumerable<Foo>> resolver;
+            (services, resolver) = _provider.CreateResolver(SAMPLE);
+
+            IQueryable<Foo> resultCtx = null;
+            ISchema schema = SchemaBuilder.New()
+                .AddServices(services.BuildServiceProvider())
+                .AddQueryType<Query>(
+                    d => d.Field(t => t.Foos)
+                        .Resolver(resolver)
+                        .Use(next => async ctx =>
+                        {
+                            await next(ctx).ConfigureAwait(false);
+                            resultCtx = ctx.Result as IQueryable<Foo>;
+                        })
+                        .UseSelection())
+                .Create();
+            IQueryExecutor executor = schema.MakeExecutable();
+
+            // act
+            executor.Execute(
+                "{ foos { nestedNull { nestedNull { nestedNull { nestedNull { bar } } } } } }");
+
+            // assert
+            Assert.NotNull(resultCtx);
+            Assert.Collection(resultCtx.ToArray(),
+                x =>
+                {
+                    Assert.Null(x.Bar);
+                    Assert.Equal(0, x.Baz);
+                    Assert.Null(x.Nested);
+                },
+                x =>
+                {
+                    Assert.Null(x.Bar);
+                    Assert.Equal(0, x.Baz);
+                    Assert.Null(x.Nested);
+                });
+        }
+
         [Fact]
         public virtual void Execute_Selection_ArrayDeep()
         {
@@ -1457,6 +1501,8 @@ public class Foo
 
             public NestedFoo Nested { get; set; }
 
+            public NestedFoo NestedNull { get; set; }
+
             public NestedFoo[] ObjectArray { get; set; }
 
             public List<NestedFoo> ObjectList { get; set; }
@@ -1602,6 +1648,8 @@ public class NestedFoo
 
             public int Baz { get; set; }
 
+            public NestedFoo NestedNull { get; set; }
+
             public NestedFoo Nested { get; set; }
 
             public List<NestedFoo> ObjectArray { get; set; }

diff --git a/src/Core/Types.Selection/SelectionClosure.cs b/src/Core/Types.Selection/SelectionClosure.cs
@@ -30,7 +30,7 @@ public SelectionClosure(Type clrType, string parameterName)
 
         public Dictionary<string, MemberAssignment> Projections { get; }
 
-        public Expression CreateMemberInit()
+        public MemberInitExpression CreateMemberInit()
         {
             NewExpression ctor = Expression.New(ClrType);
             return Expression.MemberInit(ctor, Projections.Values);

diff --git a/src/Core/Types.Selection/SelectionVisitor.cs b/src/Core/Types.Selection/SelectionVisitor.cs
@@ -54,12 +54,22 @@ protected override void LeaveLeaf(IFieldSelection selection)
 
         protected override void LeaveObject(IFieldSelection selection)
         {
-            if (selection.Field.Member is PropertyInfo)
+            if (selection.Field.Member is PropertyInfo member)
             {
-                Expression memberInit = Closures.Pop().CreateMemberInit();
+                SelectionClosure closure = Closures.Pop();
+
+                MemberInitExpression memberInit = closure.CreateMemberInit();
+
+                MemberExpression property = Expression.Property(
+                    Closures.Peek().Instance.Peek(), member);
+
+                Expression withNullCheck = Expression.Condition(
+                        Expression.Equal(property, Expression.Constant(null)),
+                        Expression.Default(memberInit.Type),
+                        memberInit);
 
                 Closures.Peek().Projections[selection.Field.Name] =
-                    Expression.Bind(selection.Field.Member, memberInit);
+                    Expression.Bind(selection.Field.Member, withNullCheck);
 
                 base.LeaveObject(selection);
             }