fix: BeforeImplicitUpdate hook through the Delete pipeline, added a bunch of comments

Author: maurei

src/Examples/JsonApiDotNetCoreExample/Data/AppDbContext.cs

@@ -58,15 +58,11 @@ protected override void OnModelCreating(ModelBuilder modelBuilder)
                 .WithOne(t => t.ParentTodoItem)
                 .HasForeignKey(t => t.ParentTodoItemId);
 
-            modelBuilder.Entity<Person>()
-                .HasOne(p => p.Passport)
-                .WithOne(p => p.Person)
-                .HasForeignKey<Person>(p => p.PassportId);
-
             modelBuilder.Entity<Passport>()
                 .HasOne(p => p.Person)
                 .WithOne(p => p.Passport)
-                .HasForeignKey<Person>(p => p.PassportId);
+                .HasForeignKey<Person>(p => p.PassportId)
+                .OnDelete(DeleteBehavior.SetNull);
 
             modelBuilder.Entity<TodoItem>()
                 .HasOne(p => p.ToOnePerson)

src/Examples/JsonApiDotNetCoreExample/Resources/LockableResourceBase.cs renamed to src/Examples/JsonApiDotNetCoreExample/Resources/LockableResource.cs

@@ -7,9 +7,9 @@
 
 namespace JsonApiDotNetCoreExample.Resources
 {
-    public abstract class LockableResourceBase<T> : ResourceDefinition<T> where T : class, IIsLockable, IIdentifiable
+    public abstract class LockableResource<T> : ResourceDefinition<T> where T : class, IIsLockable, IIdentifiable
     {
-        protected LockableResourceBase(IResourceGraph graph) : base(graph) { }
+        protected LockableResource(IResourceGraph graph) : base(graph) { }
 
         protected void DisallowLocked(IEnumerable<T> entities)
         {

src/Examples/JsonApiDotNetCoreExample/Resources/PersonResource.cs

@@ -6,25 +6,19 @@
 
 namespace JsonApiDotNetCoreExample.Resources
 {
-    public class PersonResource : LockableResourceBase<Person>
+    public class PersonResource : LockableResource<Person>
     {
         public PersonResource(IResourceGraph graph) : base(graph) { }
 
-        public override IEnumerable<string> BeforeUpdateRelationship(HashSet<string> ids, IRelationshipsDictionary<Person> resourcesByRelationship, ResourcePipeline pipeline)
+        public override IEnumerable<string> BeforeUpdateRelationship(HashSet<string> ids, IRelationshipsDictionary<Person> entitiesByRelationship, ResourcePipeline pipeline)
         {
-            BeforeImplicitUpdateRelationship(resourcesByRelationship, pipeline);
+            BeforeImplicitUpdateRelationship(entitiesByRelationship, pipeline);
             return ids;
         }
 
-        //[LoadDatabaseValues(true)]
-        //public override IEnumerable<Person> BeforeUpdate(IResourceDiff<Person> entityDiff, ResourcePipeline pipeline)
-        //{
-        //    return entityDiff.Entities;
-        //}
-
-        public override void BeforeImplicitUpdateRelationship(IRelationshipsDictionary<Person> resourcesByRelationship, ResourcePipeline pipeline)
+        public override void BeforeImplicitUpdateRelationship(IRelationshipsDictionary<Person> entitiesByRelationship, ResourcePipeline pipeline)
         {
-            resourcesByRelationship.GetByRelationship<Passport>().ToList().ForEach(kvp => DisallowLocked(kvp.Value));
+            entitiesByRelationship.GetByRelationship<Passport>().ToList().ForEach(kvp => DisallowLocked(kvp.Value));
         }
     }
 }

src/Examples/JsonApiDotNetCoreExample/Resources/TodoResource.cs

@@ -7,7 +7,7 @@
 
 namespace JsonApiDotNetCoreExample.Resources
 {
-    public class TodoResource : LockableResourceBase<TodoItem>
+    public class TodoResource : LockableResource<TodoItem>
     {
         public TodoResource(IResourceGraph graph) : base(graph) { }
 

src/JsonApiDotNetCore/Data/DefaultEntityRepository.cs

@@ -376,7 +376,7 @@ public virtual async Task<bool> DeleteAsync(TId id)
             var entity = await GetAsync(id);
             if (entity == null) return false;
             _dbSet.Remove(entity);
-            await _context.SaveChangesAsync();
+             await _context.SaveChangesAsync();
             return true;
         }
 

src/JsonApiDotNetCore/Hooks/ResourceHookExecutor.cs

@@ -88,7 +88,11 @@ public virtual IEnumerable<TEntity> BeforeDelete<TEntity>(IEnumerable<TEntity> e
                 node.Reassign(entities);
             }
 
-            foreach (var entry in node.PrincipalsToNextLayerByType())
+            /// If we're deleting an article, we're implicitly affected any owners related to it.
+            /// Here we're loading all relations onto the to-be-deleted article
+            /// if for that relation the BeforeImplicitUpdateHook is implemented,
+            /// and this hook is then executed
+            foreach (var entry in node.PrincipalsToNextLayerByRelationships())
             {
                 var dependentType = entry.Key;
                 var implicitTargets = entry.Value;

src/JsonApiDotNetCore/Hooks/Traversal/RootNode.cs

@@ -13,13 +13,15 @@ namespace JsonApiDotNetCore.Hooks
     /// </summary>
     internal class RootNode<TEntity> : IEntityNode where TEntity : class, IIdentifiable
     {
+        private readonly RelationshipProxy[] _allRelationshipsToNextLayer;
         private HashSet<TEntity> _uniqueEntities;
         public Type EntityType { get; internal set; }
         public IEnumerable UniqueEntities { get { return _uniqueEntities; } }
-        public RelationshipProxy[] RelationshipsToNextLayer { get; private set; }
-        public Dictionary<Type, Dictionary<RelationshipAttribute, IEnumerable>> PrincipalsToNextLayerByType()
+        public RelationshipProxy[] RelationshipsToNextLayer { get; }
+
+        public Dictionary<Type, Dictionary<RelationshipAttribute, IEnumerable>> PrincipalsToNextLayerByRelationships()
         {
-            return RelationshipsToNextLayer
+            return _allRelationshipsToNextLayer
                     .GroupBy(proxy => proxy.DependentType)
                     .ToDictionary(gdc => gdc.Key, gdc => gdc.ToDictionary(p => p.Attribute, p => UniqueEntities));
         }
@@ -37,11 +39,12 @@ public Dictionary<RelationshipAttribute, IEnumerable> PrincipalsToNextLayer()
         /// </summary>
         public IRelationshipsFromPreviousLayer RelationshipsFromPreviousLayer { get { return null; } }
 
-        public RootNode(IEnumerable<TEntity> uniqueEntities, RelationshipProxy[] relationships)
+        public RootNode(IEnumerable<TEntity> uniqueEntities, RelationshipProxy[] poplatedRelationships, RelationshipProxy[] allRelationships)
         {
             EntityType = typeof(TEntity);
             _uniqueEntities = new HashSet<TEntity>(uniqueEntities);
-            RelationshipsToNextLayer = relationships;
+            RelationshipsToNextLayer = poplatedRelationships;
+            _allRelationshipsToNextLayer = allRelationships;
         }
 
         /// <summary>

src/JsonApiDotNetCore/Hooks/Traversal/TraversalHelper.cs

@@ -57,8 +57,9 @@ public RootNode<TEntity> CreateRootNode<TEntity>(IEnumerable<TEntity> rootEntiti
             _processedEntities = new Dictionary<DependentType, HashSet<IIdentifiable>>();
             RegisterRelationshipProxies(typeof(TEntity));
             var uniqueEntities = ProcessEntities(rootEntities);
-            var relationshipsToNextLayer = GetPopulatedRelationships(typeof(TEntity), uniqueEntities.Cast<IIdentifiable>());
-            return new RootNode<TEntity>(uniqueEntities, relationshipsToNextLayer);
+            var populatedRelationshipsToNextLayer = GetPopulatedRelationships(typeof(TEntity), uniqueEntities.Cast<IIdentifiable>());
+            var allRelationshipsFromType = RelationshipProxies.Select(entry => entry.Value).Where(proxy => proxy.PrincipalType == typeof(TEntity)).ToArray();
+            return new RootNode<TEntity>(uniqueEntities, populatedRelationshipsToNextLayer, allRelationshipsFromType);
         }
 
         /// <summary>
@@ -108,7 +109,6 @@ public EntityChildLayer CreateNextLayer(IEnumerable<IEntityNode> nodes)
             return new EntityChildLayer(nextNodes);
         }
 
-
         /// <summary>
         /// iterates throug the <paramref name="relationships"/> dictinary and groups the values 
         /// by matching dependent type of the keys (which are relationshipattributes)