Can_Update_Many_To_Many test (failing)

Author: jaredcnance

src/JsonApiDotNetCore/Data/DefaultEntityRepository.cs

@@ -212,11 +212,14 @@ private void AttachHasManyThrough(TEntity entity, HasManyThroughAttribute hasMan
             // or we might be able to create a proxy type and implement the enumerator
             var throughRelationshipCollection = Activator.CreateInstance(hasManyThrough.ThroughProperty.PropertyType) as IList;
             hasManyThrough.ThroughProperty.SetValue(entity, throughRelationshipCollection);
+
             foreach (var pointer in pointers)
             {
                 _context.Entry(pointer).State = EntityState.Unchanged;
 
                 var throughInstance = Activator.CreateInstance(hasManyThrough.ThroughType);
+                _context.Entry(throughInstance).State = EntityState.Added;
+
                 hasManyThrough.LeftProperty.SetValue(throughInstance, entity);
                 hasManyThrough.RightProperty.SetValue(throughInstance, pointer);
                 throughRelationshipCollection.Add(throughInstance);
@@ -249,6 +252,8 @@ public virtual async Task<TEntity> UpdateAsync(TId id, TEntity entity)
             foreach (var relationship in _jsonApiContext.RelationshipsToUpdate)
                 relationship.Key.SetValue(oldEntity, relationship.Value);
 
+            AttachRelationships(entity);
+
             await _context.SaveChangesAsync();
 
             return oldEntity;

src/JsonApiDotNetCore/Serialization/JsonApiDeSerializer.cs

@@ -283,6 +283,10 @@ private object SetHasManyRelationship(object entity,
 
             if (relationships.TryGetValue(relationshipName, out RelationshipData relationshipData))
             {
+                if(relationshipData.IsHasMany == false) {
+                    throw new JsonApiException(400, $"Cannot set HasMany relationship '{attr.PublicRelationshipName}'. Value must be a JSON array of Resource Identifier Objects.");
+                }
+
                 var data = (List<ResourceIdentifierObject>)relationshipData.ExposedData;
 
                 if (data == null) return entity;

test/JsonApiDotNetCoreExampleTests/Acceptance/ManyToManyTests.cs

@@ -122,5 +122,59 @@ public async Task Can_Create_Many_To_Many()
             var persistedArticleTag = Assert.Single(persistedArticle.ArticleTags);
             Assert.Equal(tag.Id, persistedArticleTag.TagId);
         }
+
+        [Fact]
+        public async Task Can_Update_Many_To_Many()
+        {
+            // arrange
+            var context = _fixture.GetService<AppDbContext>();
+            var tag = _tagFaker.Generate();
+            var article = _articleFaker.Generate();
+            context.Tags.Add(tag);
+            context.Articles.Add(article);
+            await context.SaveChangesAsync();
+
+            var route = $"/api/v1/articles/{article.Id}";
+            var request = new HttpRequestMessage(new HttpMethod("PATCH"), route);
+            var content = new
+            {
+                data = new
+                {
+                    type = "articles",
+                    id = article.StringId,
+                    relationships = new Dictionary<string, dynamic>
+                    {
+                        {  "tags",  new {
+                            data = new [] { new
+                            {
+                                type = "tags",
+                                id = tag.StringId
+                            } }
+                        } }
+                    }
+                }
+            };
+
+            request.Content = new StringContent(JsonConvert.SerializeObject(content));
+            request.Content.Headers.ContentType = new MediaTypeHeaderValue("application/vnd.api+json");
+
+            // act
+            var response = await _fixture.Client.SendAsync(request);
+
+            // assert
+            var body = await response.Content.ReadAsStringAsync();
+            Assert.True(HttpStatusCode.OK == response.StatusCode, $"{route} returned {response.StatusCode} status code with payload: {body}");
+            
+            var articleResponse = _fixture.GetService<IJsonApiDeSerializer>().Deserialize<Article>(body);
+            Assert.NotNull(articleResponse);
+            
+            _fixture.ReloadDbContext();
+            var persistedArticle = await _fixture.Context.Articles
+                .Include(a => a.ArticleTags)
+                .SingleAsync(a => a.Id == articleResponse.Id);
+
+            var persistedArticleTag = Assert.Single(persistedArticle.ArticleTags);
+            Assert.Equal(tag.Id, persistedArticleTag.TagId);
+        }
     }
 }

test/JsonApiDotNetCoreExampleTests/Acceptance/TestFixture.cs

@@ -6,6 +6,7 @@
 using Microsoft.AspNetCore.TestHost;
 using JsonApiDotNetCore.Services;
 using JsonApiDotNetCore.Data;
+using Microsoft.EntityFrameworkCore;
 
 namespace JsonApiDotNetCoreExampleTests.Acceptance
 {
@@ -33,6 +34,11 @@ public TestFixture()
         public IJsonApiDeSerializer DeSerializer { get; private set; }
         public IJsonApiContext JsonApiContext { get; private set; }
         public T GetService<T>() => (T)_services.GetService(typeof(T));
+        
+        public void ReloadDbContext()
+        {
+            Context = new AppDbContext(GetService<DbContextOptions<AppDbContext>>());
+        }
 
         private bool disposedValue = false;
         protected virtual void Dispose(bool disposing)