Query building fix

src/JsonApiDotNetCore/Queries/IQueryLayerComposer.cs

@@ -1,5 +1,7 @@
+using System.Collections.Generic;
 using JsonApiDotNetCore.Configuration;
 using JsonApiDotNetCore.Queries.Expressions;
+using JsonApiDotNetCore.Resources.Annotations;
 
 namespace JsonApiDotNetCore.Queries
 {
@@ -12,10 +14,22 @@ public interface IQueryLayerComposer
         /// Builds a top-level filter from constraints, used to determine total resource count.
         /// </summary>
         FilterExpression GetTopFilter();
-        
+
         /// <summary>
         /// Collects constraints and builds a <see cref="QueryLayer"/> out of them, used to retrieve the actual resources.
         /// </summary>
         QueryLayer Compose(ResourceContext requestResource);
+
+        /// <summary>
+        /// Wraps a layer for a secondary endpoint into a primary layer, rewriting top-level includes.
+        /// </summary>
+        QueryLayer WrapLayerForSecondaryEndpoint<TId>(QueryLayer secondaryLayer, ResourceContext primaryResourceContext,
+            TId primaryId, RelationshipAttribute secondaryRelationship);
+
+        /// <summary>
+        /// Gets the secondary projection for a relationship endpoint.
+        /// </summary>
+        IDictionary<ResourceFieldAttribute, QueryLayer> GetSecondaryProjectionForRelationshipEndpoint(
+            ResourceContext secondaryResourceContext);
     }
 }

src/JsonApiDotNetCore/Queries/Internal/QueryLayerComposer.cs

@@ -176,6 +176,55 @@ private static IReadOnlyCollection<IncludeElementExpression> ApplyIncludeElement
             return newIncludeElements;
         }
 
+        /// <inheritdoc />
+        public QueryLayer WrapLayerForSecondaryEndpoint<TId>(QueryLayer secondaryLayer, ResourceContext primaryResourceContext, TId primaryId, RelationshipAttribute secondaryRelationship)
+        {
+            var innerInclude = secondaryLayer.Include;
+            secondaryLayer.Include = null;
+
+            var primaryIdAttribute = primaryResourceContext.Attributes.Single(x => x.Property.Name == nameof(Identifiable.Id));
+            var sparseFieldSet = new SparseFieldSetExpression(new[] { primaryIdAttribute });
+
+            var primaryProjection = GetSparseFieldSetProjection(new[] { sparseFieldSet }, primaryResourceContext) ?? new Dictionary<ResourceFieldAttribute, QueryLayer>();
+            primaryProjection[secondaryRelationship] = secondaryLayer;
+            primaryProjection[primaryIdAttribute] = null;
+
+            return new QueryLayer(primaryResourceContext)
+            {
+                Include = RewriteIncludeForSecondaryEndpoint(innerInclude, secondaryRelationship),
+                Filter = CreateFilterById(primaryId, primaryResourceContext),
+                Projection = primaryProjection
+            };
+        }
+
+        private IncludeExpression RewriteIncludeForSecondaryEndpoint(IncludeExpression relativeInclude, RelationshipAttribute secondaryRelationship)
+        {
+            var parentElement = relativeInclude != null
+                ? new IncludeElementExpression(secondaryRelationship, relativeInclude.Elements)
+                : new IncludeElementExpression(secondaryRelationship);
+
+            return new IncludeExpression(new[] {parentElement});
+        }
+
+        private FilterExpression CreateFilterById<TId>(TId id, ResourceContext resourceContext)
+        {
+            var primaryIdAttribute = resourceContext.Attributes.Single(a => a.Property.Name == nameof(Identifiable.Id));
+
+            return new ComparisonExpression(ComparisonOperator.Equals,
+                new ResourceFieldChainExpression(primaryIdAttribute), new LiteralConstantExpression(id.ToString()));
+        }
+
+        public IDictionary<ResourceFieldAttribute, QueryLayer> GetSecondaryProjectionForRelationshipEndpoint(ResourceContext secondaryResourceContext)
+        {
+            var secondaryIdAttribute = secondaryResourceContext.Attributes.Single(a => a.Property.Name == nameof(Identifiable.Id));
+            var sparseFieldSet = new SparseFieldSetExpression(new[] { secondaryIdAttribute });
+
+            var secondaryProjection = GetSparseFieldSetProjection(new[] { sparseFieldSet }, secondaryResourceContext) ?? new Dictionary<ResourceFieldAttribute, QueryLayer>();
+            secondaryProjection[secondaryIdAttribute] = null;
+
+            return secondaryProjection;
+        }
+
         protected virtual IReadOnlyCollection<IncludeElementExpression> GetIncludeElements(IReadOnlyCollection<IncludeElementExpression> includeElements, ResourceContext resourceContext)
         {
             if (resourceContext == null) throw new ArgumentNullException(nameof(resourceContext));

src/JsonApiDotNetCore/Resources/ResourceFactory.cs

@@ -3,6 +3,8 @@
 using System.Linq;
 using System.Linq.Expressions;
 using System.Reflection;
+using JsonApiDotNetCore.Queries.Internal.QueryableBuilding;
+using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.DependencyInjection;
 
 namespace JsonApiDotNetCore.Resources
@@ -73,7 +75,12 @@ public NewExpression CreateNewExpression(Type resourceType)
                     object constructorArgument =
                         ActivatorUtilities.GetServiceOrCreateInstance(_serviceProvider, constructorParameter.ParameterType);
 
-                    constructorArguments.Add(Expression.Constant(constructorArgument));
+                    var argumentExpression = typeof(DbContext).Assembly.GetName().Version.Major >= 5
+                        // Workaround for https://github.com/dotnet/efcore/issues/20502 to not fail on injected DbContext in EF Core 5.
+                        ? CreateTupleAccessExpressionForConstant(constructorArgument, constructorArgument.GetType())
+                        : Expression.Constant(constructorArgument);
+
+                    constructorArguments.Add(argumentExpression);
                 }
                 catch (Exception exception)
                 {
@@ -86,6 +93,19 @@ public NewExpression CreateNewExpression(Type resourceType)
             return Expression.New(longestConstructor, constructorArguments);
         }
 
+        private static Expression CreateTupleAccessExpressionForConstant(object value, Type type)
+        {
+            MethodInfo tupleCreateMethod = typeof(Tuple).GetMethods()
+                .Single(m => m.Name == "Create" && m.IsGenericMethod && m.GetGenericArguments().Length == 1);
+
+            MethodInfo constructedTupleCreateMethod = tupleCreateMethod.MakeGenericMethod(type);
+
+            ConstantExpression constantExpression = Expression.Constant(value, type);
+
+            MethodCallExpression tupleCreateCall = Expression.Call(constructedTupleCreateMethod, constantExpression);
+            return Expression.Property(tupleCreateCall, "Item1");
+        }
+
         private static bool HasSingleConstructorWithoutParameters(Type type)
         {
             ConstructorInfo[] constructors = type.GetConstructors().Where(c => !c.IsStatic).ToArray();

src/JsonApiDotNetCore/Services/JsonApiResourceService.cs

@@ -196,24 +196,18 @@ public virtual async Task<TResource> GetRelationshipAsync(TId id, string relatio
             _hookExecutor?.BeforeRead<TResource>(ResourcePipeline.GetRelationship, id.ToString());
 
             var secondaryLayer = _queryLayerComposer.Compose(_request.SecondaryResource);
-
-            var secondaryIdAttribute = _request.SecondaryResource.Attributes.Single(a => a.Property.Name == nameof(Identifiable.Id));
-
+            secondaryLayer.Projection = _queryLayerComposer.GetSecondaryProjectionForRelationshipEndpoint(_request.SecondaryResource);
             secondaryLayer.Include = null;
-            secondaryLayer.Projection = new Dictionary<ResourceFieldAttribute, QueryLayer>
-            {
-                [secondaryIdAttribute] = null
-            };
-
-            var primaryLayer = GetPrimaryLayerForSecondaryEndpoint(secondaryLayer, id);
+
+            var primaryLayer = _queryLayerComposer.WrapLayerForSecondaryEndpoint(secondaryLayer, _request.PrimaryResource, id, _request.Relationship);
 
             var primaryResources = await _repository.GetAsync(primaryLayer);
-            
+
             var primaryResource = primaryResources.SingleOrDefault();
             AssertPrimaryResourceExists(primaryResource);
 
             if (_hookExecutor != null)
-            {   
+            {
                 _hookExecutor.AfterRead(AsList(primaryResource), ResourcePipeline.GetRelationship);
                 primaryResource = _hookExecutor.OnReturn(AsList(primaryResource), ResourcePipeline.GetRelationship).Single();
             }
@@ -233,7 +227,7 @@ public virtual async Task<object> GetSecondaryAsync(TId id, string relationshipN
             _hookExecutor?.BeforeRead<TResource>(ResourcePipeline.GetRelationship, id.ToString());
 
             var secondaryLayer = _queryLayerComposer.Compose(_request.SecondaryResource);
-            var primaryLayer = GetPrimaryLayerForSecondaryEndpoint(secondaryLayer, id);
+            var primaryLayer = _queryLayerComposer.WrapLayerForSecondaryEndpoint(secondaryLayer, _request.PrimaryResource, id, _request.Relationship);
 
             var primaryResources = await _repository.GetAsync(primaryLayer);
 
@@ -249,35 +243,6 @@ public virtual async Task<object> GetSecondaryAsync(TId id, string relationshipN
             return _request.Relationship.GetValue(primaryResource);
         }
 
-        private QueryLayer GetPrimaryLayerForSecondaryEndpoint(QueryLayer secondaryLayer, TId primaryId)
-        {
-            var innerInclude = secondaryLayer.Include;
-            secondaryLayer.Include = null;
-
-            var primaryIdAttribute =
-                _request.PrimaryResource.Attributes.Single(a => a.Property.Name == nameof(Identifiable.Id));
-
-            return new QueryLayer(_request.PrimaryResource)
-            {
-                Include = RewriteIncludeForSecondaryEndpoint(innerInclude),
-                Filter = CreateFilterById(primaryId),
-                Projection = new Dictionary<ResourceFieldAttribute, QueryLayer>
-                {
-                    [primaryIdAttribute] = null,
-                    [_request.Relationship] = secondaryLayer
-                }
-            };
-        }
-
-        private IncludeExpression RewriteIncludeForSecondaryEndpoint(IncludeExpression relativeInclude)
-        {
-            var parentElement = relativeInclude != null
-                ? new IncludeElementExpression(_request.Relationship, relativeInclude.Elements)
-                : new IncludeElementExpression(_request.Relationship);
-
-            return new IncludeExpression(new[] {parentElement});
-        }
-
         /// <inheritdoc />
         public virtual async Task<TResource> UpdateAsync(TId id, TResource requestResource)
         {
@@ -320,7 +285,7 @@ public virtual async Task UpdateRelationshipAsync(TId id, string relationshipNam
             AssertRelationshipExists(relationshipName);
 
             var secondaryLayer = _queryLayerComposer.Compose(_request.SecondaryResource);
-            var primaryLayer = GetPrimaryLayerForSecondaryEndpoint(secondaryLayer, id);
+            var primaryLayer = _queryLayerComposer.WrapLayerForSecondaryEndpoint(secondaryLayer, _request.PrimaryResource, id, _request.Relationship);
             primaryLayer.Projection = null;
 
             var primaryResources = await _repository.GetAsync(primaryLayer);