GetAffected syntax in resource hook helpers

src/Examples/GettingStarted/Properties/launchSettings.json

@@ -17,7 +17,8 @@
     },
     "GettingStarted": {
       "commandName": "Project",
-      "launchBrowser": true
+      "launchBrowser": true,
+      "environmentVariables": {}
     }
   }
-}
+}

src/Examples/JsonApiDotNetCoreExample/Properties/launchSettings.json

@@ -25,4 +25,4 @@
       }
     }
   }
-}
+}

src/Examples/NoEntityFrameworkExample/Properties/launchSettings.json

@@ -16,7 +16,8 @@
       }
     },
     "NoEntityFrameworkExample": {
-      "commandName": "Project"
+      "commandName": "Project",
+      "environmentVariables": {}
     }
   }
 }

src/Examples/ResourceEntitySeparationExample/Properties/launchSettings.json

@@ -1,23 +1,24 @@
 {
-    "iisSettings": {
-        "windowsAuthentication": false,
-        "anonymousAuthentication": true,
-        "iisExpress": {
-            "applicationUrl": "http://localhost:57181/",
-            "sslPort": 0
-        }
+  "iisSettings": {
+    "windowsAuthentication": false,
+    "anonymousAuthentication": true,
+    "iisExpress": {
+      "applicationUrl": "http://localhost:57181/",
+      "sslPort": 0
+    }
+  },
+  "profiles": {
+    "IIS Express": {
+      "commandName": "IISExpress",
+      "launchBrowser": true,
+      "launchUrl": "api/v1/students",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development"
+      }
     },
-    "profiles": {
-        "IIS Express": {
-            "commandName": "IISExpress",
-            "launchBrowser": true,
-            "launchUrl": "api/v1/students",
-            "environmentVariables": {
-                "ASPNETCORE_ENVIRONMENT": "Development"
-            }
-        },
-        "ResourceEntitySeparationExample": {
-            "commandName": "Project"
-        }
+    "ResourceEntitySeparationExample": {
+      "commandName": "Project",
+      "environmentVariables": {}
     }
-}
+  }
+}

src/JsonApiDotNetCore/Extensions/IServiceCollectionExtensions.cs

@@ -64,7 +64,7 @@ public static IServiceCollection AddJsonApi(
             var config = new JsonApiOptions();
             configureOptions(config);
 
-            if(autoDiscover != null)
+            if (autoDiscover != null)
             {
                 var facade = new ServiceDiscoveryFacade(services, config.ResourceGraphBuilder);
                 autoDiscover(facade);
@@ -159,7 +159,7 @@ public static void AddJsonApiInternals(
             services.AddScoped<IControllerContext, Services.ControllerContext>();
             services.AddScoped<IDocumentBuilderOptionsProvider, DocumentBuilderOptionsProvider>();
 
-           
+
             if (jsonApiOptions.EnableResourceHooks)
             {
                 services.AddSingleton(typeof(IHooksDiscovery<>), typeof(HooksDiscovery<>));
@@ -204,7 +204,7 @@ public static void SerializeAsJsonApi(this MvcOptions options, JsonApiOptions js
         /// Adds all required registrations for the service to the container
         /// </summary>
         /// <exception cref="JsonApiSetupException"/>
-        public static IServiceCollection AddResourceService<T>(this IServiceCollection services) 
+        public static IServiceCollection AddResourceService<T>(this IServiceCollection services)
         {
             var typeImplementsAnExpectedInterface = false;
 
@@ -213,28 +213,29 @@ public static IServiceCollection AddResourceService<T>(this IServiceCollection s
             // it is _possible_ that a single concrete type could be used for multiple resources...
             var resourceDescriptors = GetResourceTypesFromServiceImplementation(serviceImplementationType);
 
-            foreach(var resourceDescriptor in resourceDescriptors)
+            foreach (var resourceDescriptor in resourceDescriptors)
             {
-                foreach(var openGenericType in ServiceDiscoveryFacade.ServiceInterfaces)
+                foreach (var openGenericType in ServiceDiscoveryFacade.ServiceInterfaces)
                 {
                     // A shorthand interface is one where the id type is ommitted
                     // e.g. IResourceService<T> is the shorthand for IResourceService<T, TId>
                     var isShorthandInterface = (openGenericType.GetTypeInfo().GenericTypeParameters.Length == 1);
-                    if(isShorthandInterface && resourceDescriptor.IdType != typeof(int))
+                    if (isShorthandInterface && resourceDescriptor.IdType != typeof(int))
                         continue; // we can't create a shorthand for id types other than int
 
                     var concreteGenericType = isShorthandInterface
                         ? openGenericType.MakeGenericType(resourceDescriptor.ResourceType)
                         : openGenericType.MakeGenericType(resourceDescriptor.ResourceType, resourceDescriptor.IdType);
 
-                    if(concreteGenericType.IsAssignableFrom(serviceImplementationType)) {
+                    if (concreteGenericType.IsAssignableFrom(serviceImplementationType))
+                    {
                         services.AddScoped(concreteGenericType, serviceImplementationType);
                         typeImplementsAnExpectedInterface = true;
                     }
                 }
             }
 
-            if(typeImplementsAnExpectedInterface == false)
+            if (typeImplementsAnExpectedInterface == false)
                 throw new JsonApiSetupException($"{serviceImplementationType} does not implement any of the expected JsonApiDotNetCore interfaces.");
 
             return services;
@@ -244,12 +245,12 @@ private static HashSet<ResourceDescriptor> GetResourceTypesFromServiceImplementa
         {
             var resourceDecriptors = new HashSet<ResourceDescriptor>();
             var interfaces = type.GetInterfaces();
-            foreach(var i in interfaces)
+            foreach (var i in interfaces)
             {
-                if(i.IsGenericType)
+                if (i.IsGenericType)
                 {
                     var firstGenericArgument = i.GenericTypeArguments.FirstOrDefault();
-                    if(TypeLocator.TryGetResourceDescriptor(firstGenericArgument, out var resourceDescriptor) == true)
+                    if (TypeLocator.TryGetResourceDescriptor(firstGenericArgument, out var resourceDescriptor) == true)
                     {
                         resourceDecriptors.Add(resourceDescriptor);
                     }

src/JsonApiDotNetCore/Hooks/Execution/EntityDiffs.cs → src/JsonApiDotNetCore/Hooks/Execution/DiffableEntityHashSet.cs

@@ -1,10 +1,13 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
-using System.Collections.ObjectModel;
 using System.Linq;
+using System.Linq.Expressions;
+using System.Reflection;
+using JsonApiDotNetCore.Extensions;
 using JsonApiDotNetCore.Internal;
 using JsonApiDotNetCore.Models;
+using JsonApiDotNetCore.Services;
 
 namespace JsonApiDotNetCore.Hooks
 {
@@ -15,68 +18,79 @@ namespace JsonApiDotNetCore.Hooks
     /// Also contains information about updated relationships through 
     /// implementation of IRelationshipsDictionary<typeparamref name="TResource"/>>
     /// </summary>
-    public interface IEntityDiffs<TResource> :  IEnumerable<EntityDiffPair<TResource>> where TResource : class, IIdentifiable
+    public interface IDiffableEntityHashSet<TResource> : IEntityHashSet<TResource> where TResource : class, IIdentifiable
     {
         /// <summary>
-        /// The database values of the resources affected by the request.
+        /// Iterates over diffs, which is the affected entity from the request
+        ///  with their associated current value from the database.
         /// </summary>
-        HashSet<TResource> DatabaseValues { get; }
-
-        /// <summary>
-        /// The resources that were affected by the request.
-        /// </summary>
-        EntityHashSet<TResource> Entities { get; }
+        IEnumerable<EntityDiffPair<TResource>> GetDiffs();
 
     }
 
     /// <inheritdoc />
-    public class EntityDiffs<TResource> : IEntityDiffs<TResource> where TResource : class, IIdentifiable
+    public class DiffableEntityHashSet<TResource> : EntityHashSet<TResource>, IDiffableEntityHashSet<TResource> where TResource : class, IIdentifiable
     {
-        /// <inheritdoc />
-        public HashSet<TResource> DatabaseValues { get => _databaseValues ?? ThrowNoDbValuesError(); }
-        /// <inheritdoc />
-        public EntityHashSet<TResource> Entities { get; private set; }
-
         private readonly HashSet<TResource> _databaseValues;
         private readonly bool _databaseValuesLoaded;
+        private Dictionary<PropertyInfo, HashSet<TResource>> _updatedAttributes;
 
-        public EntityDiffs(HashSet<TResource> requestEntities,
+        public DiffableEntityHashSet(HashSet<TResource> requestEntities,
                           HashSet<TResource> databaseEntities,
-                          Dictionary<RelationshipAttribute, HashSet<TResource>> relationships)
+                          Dictionary<RelationshipAttribute, HashSet<TResource>> relationships,
+                          Dictionary<PropertyInfo, HashSet<TResource>> updatedAttributes)
+            : base(requestEntities, relationships)
         {
-            Entities = new EntityHashSet<TResource>(requestEntities, relationships);
             _databaseValues = databaseEntities;
             _databaseValuesLoaded |= _databaseValues != null;
+            _updatedAttributes = updatedAttributes;
         }
 
         /// <summary>
         /// Used internally by the ResourceHookExecutor to make live a bit easier with generics
         /// </summary>
-        internal EntityDiffs(IEnumerable requestEntities,
+        internal DiffableEntityHashSet(IEnumerable requestEntities,
                   IEnumerable databaseEntities,
-                  Dictionary<RelationshipAttribute, IEnumerable> relationships)
-            : this((HashSet<TResource>)requestEntities, (HashSet<TResource>)databaseEntities, TypeHelper.ConvertRelationshipDictionary<TResource>(relationships)) { }
+                  Dictionary<RelationshipAttribute, IEnumerable> relationships,
+                  IJsonApiContext jsonApiContext)
+            : this((HashSet<TResource>)requestEntities, (HashSet<TResource>)databaseEntities, TypeHelper.ConvertRelationshipDictionary<TResource>(relationships),
+              TypeHelper.ConvertAttributeDictionary(jsonApiContext.AttributesToUpdate, (HashSet<TResource>)requestEntities))
+        { }
 
 
         /// <inheritdoc />
-        public IEnumerator<EntityDiffPair<TResource>> GetEnumerator()
+        public IEnumerable<EntityDiffPair<TResource>> GetDiffs()
         {
             if (!_databaseValuesLoaded) ThrowNoDbValuesError();
 
-            foreach (var entity in Entities)
+            foreach (var entity in this)
             {
-                TResource currentValueInDatabase = null;
-                currentValueInDatabase = _databaseValues.Single(e => entity.StringId == e.StringId);
+                TResource currentValueInDatabase = _databaseValues.Single(e => entity.StringId == e.StringId);
                 yield return new EntityDiffPair<TResource>(entity, currentValueInDatabase);
             }
         }
 
         /// <inheritdoc />
-        IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
+        public new HashSet<TResource> GetAffected(Expression<Func<TResource, object>> NavigationAction)
+        {
+            var propertyInfo = TypeHelper.ParseNavigationExpression(NavigationAction);
+            var propertyType = propertyInfo.PropertyType;
+            if (propertyType.Inherits(typeof(IEnumerable))) propertyType = TypeHelper.GetTypeOfList(propertyType);
+            if (propertyType.Implements<IIdentifiable>())
+            {
+                // the navigation action references a relationship. Redirect the call to the relationship dictionary. 
+                return base.GetAffected(NavigationAction);
+            }
+            else if (_updatedAttributes.TryGetValue(propertyInfo, out HashSet<TResource> entities))
+            {
+                return entities;
+            }
+            return new HashSet<TResource>();
+        }
 
         private HashSet<TResource> ThrowNoDbValuesError()
         {
-            throw new MemberAccessException("Cannot access database entities if the LoadDatabaseValues option is set to false");
+            throw new MemberAccessException("Cannot iterate over the diffs if the LoadDatabaseValues option is set to false");
         }
     }
 

src/JsonApiDotNetCore/Hooks/Execution/EntityHashSet.cs

@@ -5,6 +5,7 @@
 using System;
 using System.Collections.ObjectModel;
 using System.Collections.Immutable;
+using System.Linq.Expressions;
 
 namespace JsonApiDotNetCore.Hooks
 {
@@ -26,7 +27,7 @@ public interface IEntityHashSet<TResource> : IByAffectedRelationships<TResource>
     /// </summary>
     public class EntityHashSet<TResource> : HashSet<TResource>, IEntityHashSet<TResource> where TResource : class, IIdentifiable
     {
-    
+
 
         /// <inheritdoc />
         public Dictionary<RelationshipAttribute, HashSet<TResource>> AffectedRelationships { get => _relationships; }
@@ -53,9 +54,15 @@ public Dictionary<RelationshipAttribute, HashSet<TResource>> GetByRelationship(T
         }
 
         /// <inheritdoc />
-        public Dictionary<RelationshipAttribute, HashSet<TResource>> GetByRelationship<TRelatedResource>()  where TRelatedResource : class, IIdentifiable
+        public Dictionary<RelationshipAttribute, HashSet<TResource>> GetByRelationship<TRelatedResource>() where TRelatedResource : class, IIdentifiable
         {
             return GetByRelationship(typeof(TRelatedResource));
         }
+
+        /// <inheritdoc />
+        public HashSet<TResource> GetAffected(Expression<Func<TResource, object>> NavigationAction)
+        {
+            return _relationships.GetAffected(NavigationAction);
+        }
     }
 }

src/JsonApiDotNetCore/Hooks/Execution/RelationshipsDictionary.cs

@@ -2,6 +2,8 @@
 using System.Collections;
 using System.Collections.Generic;
 using System.Linq;
+using System.Linq.Expressions;
+using System.Reflection;
 using JsonApiDotNetCore.Internal;
 using JsonApiDotNetCore.Models;
 
@@ -15,13 +17,9 @@ public interface IRelationshipsDictionary { }
     /// <summary>
     /// An interface that is implemented to expose a relationship dictionary on another class.
     /// </summary>
-    public interface IByAffectedRelationships<TDependentResource> : 
+    public interface IByAffectedRelationships<TDependentResource> :
         IRelationshipGetters<TDependentResource> where TDependentResource : class, IIdentifiable
     {
-        /// todo: expose getters that behave something like this:
-        /// relationshipDictionary.GetAffected( entity => entity.NavigationProperty ).
-        /// see https://stackoverflow.com/a/17116267/4441216
-
         /// <summary>
         /// Gets a dictionary of affected resources grouped by affected relationships.
         /// </summary>
@@ -31,10 +29,11 @@ public interface IByAffectedRelationships<TDependentResource> :
     /// <summary>
     /// A helper class that provides insights in which relationships have been updated for which entities.
     /// </summary>
-    public interface IRelationshipsDictionary<TDependentResource> : 
-        IRelationshipGetters<TDependentResource>, 
-        IReadOnlyDictionary<RelationshipAttribute, HashSet<TDependentResource>>, 
-        IRelationshipsDictionary where TDependentResource : class, IIdentifiable { }
+    public interface IRelationshipsDictionary<TDependentResource> :
+        IRelationshipGetters<TDependentResource>,
+        IReadOnlyDictionary<RelationshipAttribute, HashSet<TDependentResource>>,
+        IRelationshipsDictionary where TDependentResource : class, IIdentifiable
+    { }
 
     /// <summary>
     /// A helper class that provides insights in which relationships have been updated for which entities.
@@ -49,16 +48,24 @@ public interface IRelationshipGetters<TResource> where TResource : class, IIdent
         /// Gets a dictionary of all entities that have an affected relationship to type <paramref name="principalType"/>
         /// </summary>
         Dictionary<RelationshipAttribute, HashSet<TResource>> GetByRelationship(Type relatedResourceType);
+
+        /// <summary>
+        /// Gets a collection of all the entities for the property within <paramref name="NavigationAction"/>
+        /// has been affected by the request
+        /// </summary>
+        /// <param name="NavigationAction"></param>
+        HashSet<TResource> GetAffected(Expression<Func<TResource, object>> NavigationAction);
     }
 
+
     /// <summary>
     /// Implementation of IAffectedRelationships{TDependentResource}
     /// 
     /// It is practically a ReadOnlyDictionary{RelationshipAttribute, HashSet{TDependentResource}} dictionary
     /// with the two helper methods defined on IAffectedRelationships{TDependentResource}.
     /// </summary>
     public class RelationshipsDictionary<TResource> :
-        Dictionary<RelationshipAttribute, HashSet<TResource>>, 
+        Dictionary<RelationshipAttribute, HashSet<TResource>>,
         IRelationshipsDictionary<TResource> where TResource : class, IIdentifiable
     {
         /// <summary>
@@ -70,7 +77,7 @@ public RelationshipsDictionary(Dictionary<RelationshipAttribute, HashSet<TResour
         /// <summary>
         /// Used internally by the ResourceHookExecutor to make live a bit easier with generics
         /// </summary>
-        internal RelationshipsDictionary(Dictionary<RelationshipAttribute, IEnumerable> relationships) 
+        internal RelationshipsDictionary(Dictionary<RelationshipAttribute, IEnumerable> relationships)
             : this(TypeHelper.ConvertRelationshipDictionary<TResource>(relationships)) { }
 
         /// <inheritdoc />
@@ -84,5 +91,12 @@ public Dictionary<RelationshipAttribute, HashSet<TResource>> GetByRelationship(T
         {
             return this.Where(p => p.Key.DependentType == relatedType).ToDictionary(p => p.Key, p => p.Value);
         }
+
+        /// <inheritdoc />
+        public HashSet<TResource> GetAffected(Expression<Func<TResource, object>> NavigationAction)
+        {
+            var property = TypeHelper.ParseNavigationExpression(NavigationAction);
+            return this.Where(p => p.Key.InternalRelationshipName == property.Name).Select(p => p.Value).SingleOrDefault();
+        }
     }
 }