fix: bugs with inverse relationship loading

Author: maurei

src/JsonApiDotNetCore/Data/DefaultEntityRepository.cs

@@ -174,20 +174,34 @@ public virtual async Task<TEntity> CreateAsync(TEntity entity)
         /// </summary>
         private void LoadInverseRelationships(object trackedRelationshipValue, RelationshipAttribute relationshipAttr)
         {
-            if (relationshipAttr.InverseNavigation == null) return;
+            if (relationshipAttr.InverseNavigation == null || trackedRelationshipValue == null) return;
             if (relationshipAttr is HasOneAttribute hasOneAttr)
             {
-                _context.Entry((IIdentifiable)trackedRelationshipValue).Reference(hasOneAttr.InverseNavigation).Load();
+                var relationEntry = _context.Entry((IIdentifiable)trackedRelationshipValue);
+                if (IsHasOneRelationship(hasOneAttr.InverseNavigation, trackedRelationshipValue.GetType()))
+                {
+                    relationEntry.Reference(hasOneAttr.InverseNavigation).Load();
+                } else
+                {
+                    relationEntry.Collection(hasOneAttr.InverseNavigation).Load();
+                }
             }
-            else if (relationshipAttr is HasManyAttribute hasManyAttr)
+            else if (relationshipAttr is HasManyAttribute hasManyAttr && !(relationshipAttr is HasManyThroughAttribute))
             {
                 foreach (IIdentifiable relationshipValue in (IList)trackedRelationshipValue) 
                 {
-                    _context.Entry((IIdentifiable)trackedRelationshipValue).Reference(hasManyAttr.InverseNavigation).Load();
+                    _context.Entry(relationshipValue).Reference(hasManyAttr.InverseNavigation).Load();
                 }
             }
         }
 
+        private bool IsHasOneRelationship(string inverseNavigation, Type type)
+        {
+            var relationshipAttr = _jsonApiContext.ResourceGraph.GetContextEntity(type).Relationships.Single(r => r.InternalRelationshipName == inverseNavigation);
+            if (relationshipAttr is HasOneAttribute) return true;
+            return false;
+        }
+
 
         /// <inheritdoc />
         public void DetachRelationshipPointers(TEntity entity)

test/JsonApiDotNetCoreExampleTests/Acceptance/Spec/UpdatingRelationshipsTests.cs

@@ -633,7 +633,7 @@ public async Task Updating_ToOne_Relationship_With_Implicit_Remove()
             var person2 = _personFaker.Generate();
             context.People.AddRange(new List<Person>() { person1, person2 });
             await context.SaveChangesAsync();
-
+            var passportId = person1.PassportId;
             var content = new
             {
                 data = new
@@ -644,7 +644,7 @@ public async Task Updating_ToOne_Relationship_With_Implicit_Remove()
                     {
                         { "passport", new
                             {
-                                data = new { type = "passports", id = $"{person1.PassportId}" }
+                                data = new { type = "passports", id = $"{passportId}" }
                             }
                         }
                     }
@@ -661,12 +661,75 @@ public async Task Updating_ToOne_Relationship_With_Implicit_Remove()
 
             // Act
             var response = await _fixture.Client.SendAsync(request);
+            var body = await response.Content.ReadAsStringAsync();
 
             // Assert
+           
+            Assert.True(HttpStatusCode.OK == response.StatusCode, $"{route} returned {response.StatusCode} status code with payload: {body}");
+            var dbPerson = context.People.AsNoTracking().Where(p => p.Id == person2.Id).Include("Passport").FirstOrDefault();
+            Assert.Equal(passportId, dbPerson.Passport.Id);
+        }
+
+        [Fact]
+        public async Task Updating_ToMany_Relationship_With_Implicit_Remove()
+        {
+            // Arrange
+            var context = _fixture.GetService<AppDbContext>();
+            var person1 = _personFaker.Generate();
+            person1.TodoItems = _todoItemFaker.Generate(3).ToList();
+            var person2 = _personFaker.Generate();
+            person2.TodoItems = _todoItemFaker.Generate(2).ToList();
+            context.People.AddRange(new List<Person>() { person1, person2 });
+            await context.SaveChangesAsync();
+            var todoItem1Id = person1.TodoItems[0].Id;
+            var todoItem2Id = person1.TodoItems[1].Id;
+
+            var content = new
+            {
+                data = new
+                {
+                    type = "people",
+                    id = person2.Id,
+                    relationships = new Dictionary<string, object>
+                    {
+                        { "todo-items", new
+                            {
+                                data = new List<object>
+                                {
+                                    new {
+                                        type = "todo-items",
+                                        id = $"{todoItem1Id}"
+                                    },
+                                    new {
+                                        type = "todo-items",
+                                        id = $"{todoItem2Id}"
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+            };
+
+            var httpMethod = new HttpMethod("PATCH");
+            var route = $"/api/v1/people/{person2.Id}";
+            var request = new HttpRequestMessage(httpMethod, route);
+
+            string serializedContent = JsonConvert.SerializeObject(content);
+            request.Content = new StringContent(serializedContent);
+            request.Content.Headers.ContentType = new MediaTypeHeaderValue("application/vnd.api+json");
+
+            // Act
+            var response = await _fixture.Client.SendAsync(request);
             var body = await response.Content.ReadAsStringAsync();
 
-            Assert.True(HttpStatusCode.OK == response.StatusCode, $"{route} returned {response.StatusCode} status code with payload: {body}");
+            // Assert
 
+            Assert.True(HttpStatusCode.OK == response.StatusCode, $"{route} returned {response.StatusCode} status code with payload: {body}");
+            var dbPerson = context.People.AsNoTracking().Where(p => p.Id == person2.Id).Include("TodoItems").FirstOrDefault();
+            Assert.Equal(2, dbPerson.TodoItems.Count);
+            Assert.NotNull(dbPerson.TodoItems.SingleOrDefault(ti => ti.Id == todoItem1Id));
+            Assert.NotNull(dbPerson.TodoItems.SingleOrDefault(ti => ti.Id == todoItem2Id));
         }
     }
 }