refactor(DocumentBuilder): dont lookup resource on graph multiple times

Author: jaredcnance

src/JsonApiDotNetCore/Builders/DocumentBuilder.cs

@@ -18,8 +18,8 @@ public class DocumentBuilder : IDocumentBuilder
         private readonly IScopedServiceProvider _scopedServiceProvider;
 
         public DocumentBuilder(
-            IJsonApiContext jsonApiContext, 
-            IRequestMeta requestMeta = null, 
+            IJsonApiContext jsonApiContext,
+            IRequestMeta requestMeta = null,
             IDocumentBuilderOptionsProvider documentBuilderOptionsProvider = null,
             IScopedServiceProvider scopedServiceProvider = null)
         {
@@ -112,7 +112,8 @@ public ResourceObject GetData(ContextEntity contextEntity, IIdentifiable entity)
 
         public ResourceObject GetData(ContextEntity contextEntity, IIdentifiable entity, IResourceDefinition resourceDefinition = null)
         {
-            var data = new ResourceObject {
+            var data = new ResourceObject
+            {
                 Type = contextEntity.EntityName,
                 Id = entity.StringId
             };
@@ -177,9 +178,8 @@ private RelationshipData GetRelationshipData(RelationshipAttribute attr, Context
                     relationshipData.Links.Related = linkBuilder.GetRelatedRelationLink(contextEntity.EntityName, entity.StringId, attr.PublicRelationshipName);
             }
 
-             // this only includes the navigation property, we need to actually check the navigation property Id
+            // this only includes the navigation property, we need to actually check the navigation property Id
             var navigationEntity = _jsonApiContext.ContextGraph.GetRelationshipValue(entity, attr);
-
             if (navigationEntity == null)
                 relationshipData.SingleData = attr.IsHasOne
                     ? GetIndependentRelationshipIdentifier((HasOneAttribute)attr, entity)
@@ -196,14 +196,14 @@ private List<ResourceObject> GetIncludedEntities(List<ResourceObject> included,
         {
             if (_jsonApiContext.IncludedRelationships != null)
             {
-                foreach(var relationshipName in _jsonApiContext.IncludedRelationships)
+                foreach (var relationshipName in _jsonApiContext.IncludedRelationships)
                 {
                     var relationshipChain = relationshipName.Split('.');
 
                     var contextEntity = rootContextEntity;
                     var entity = rootResource;
                     included = IncludeRelationshipChain(included, rootContextEntity, rootResource, relationshipChain, 0);
-                }                
+                }
             }
 
             return included;
@@ -214,7 +214,7 @@ private List<ResourceObject> IncludeRelationshipChain(
         {
             var requestedRelationship = relationshipChain[relationshipChainIndex];
             var relationship = parentEntity.Relationships.FirstOrDefault(r => r.PublicRelationshipName == requestedRelationship);
-            var navigationEntity = _jsonApiContext.ContextGraph.GetRelationship(parentResource, relationship.InternalRelationshipName);    
+            var navigationEntity = _jsonApiContext.ContextGraph.GetRelationship(parentResource, relationship.InternalRelationshipName);
             if (navigationEntity is IEnumerable hasManyNavigationEntity)
             {
                 foreach (IIdentifiable includedEntity in hasManyNavigationEntity)
@@ -227,23 +227,23 @@ private List<ResourceObject> IncludeRelationshipChain(
             {
                 included = AddIncludedEntity(included, (IIdentifiable)navigationEntity);
                 included = IncludeSingleResourceRelationships(included, (IIdentifiable)navigationEntity, relationship, relationshipChain, relationshipChainIndex);
-            }        
+            }
 
             return included;
         }
 
         private List<ResourceObject> IncludeSingleResourceRelationships(
             List<ResourceObject> included, IIdentifiable navigationEntity, RelationshipAttribute relationship, string[] relationshipChain, int relationshipChainIndex)
         {
-            if (relationshipChainIndex < relationshipChain.Length) 
+            if (relationshipChainIndex < relationshipChain.Length)
             {
                 var nextContextEntity = _jsonApiContext.ContextGraph.GetContextEntity(relationship.Type);
                 var resource = (IIdentifiable)navigationEntity;
                 // recursive call
-                if(relationshipChainIndex < relationshipChain.Length - 1)
+                if (relationshipChainIndex < relationshipChain.Length - 1)
                     included = IncludeRelationshipChain(included, nextContextEntity, resource, relationshipChain, relationshipChainIndex + 1);
             }
-            
+
             return included;
         }
 
@@ -289,7 +289,11 @@ private List<ResourceIdentifierObject> GetRelationships(IEnumerable<object> enti
             var relationships = new List<ResourceIdentifierObject>();
             foreach (var entity in entities)
             {
-                typeName = _jsonApiContext.ContextGraph.GetContextEntity(entity.GetType()).EntityName;
+                // this method makes the assumption that entities is a homogenous collection
+                // so, we just lookup the type of the first entity on the graph
+                // this is better than trying to get it from the generic parameter since it could
+                // be less specific than what is registered on the graph (e.g. IEnumerable<object>) 
+                typeName = typeName ?? _jsonApiContext.ContextGraph.GetContextEntity(entity.GetType()).EntityName;
                 relationships.Add(new ResourceIdentifierObject
                 {
                     Type = typeName,
@@ -304,7 +308,7 @@ private ResourceIdentifierObject GetRelationship(object entity)
             var objType = entity.GetType();
             var contextEntity = _jsonApiContext.ContextGraph.GetContextEntity(objType);
 
-            if(entity is IIdentifiable identifiableEntity)
+            if (entity is IIdentifiable identifiableEntity)
                 return new ResourceIdentifierObject
                 {
                     Type = contextEntity.EntityName,

src/JsonApiDotNetCore/Internal/ContextGraph.cs

@@ -18,6 +18,10 @@ public interface IContextGraph
         /// <code>
         /// _graph.GetRelationship(todoItem, nameof(TodoItem.Owner));
         /// </code>
+        /// <remarks>
+        /// This method will not work with HasManyThrough relationships. 
+        /// You should instead use the <see cref="GetRelationshipValue" /> method instead.
+        /// </remarks>
         /// </example>
         object GetRelationship<TParent>(TParent resource, string propertyName);