Repro for issue 988

Directory.Build.props

@@ -2,8 +2,8 @@
   <PropertyGroup>
     <NetCoreAppVersion>netcoreapp3.1</NetCoreAppVersion>
     <AspNetCoreVersion>3.1.*</AspNetCoreVersion>
-    <EFCoreVersion>3.1.*</EFCoreVersion>
-    <NpgsqlPostgreSQLVersion>3.1.*</NpgsqlPostgreSQLVersion>
+    <EFCoreVersion>5.0.*</EFCoreVersion>
+    <NpgsqlPostgreSQLVersion>5.0.*</NpgsqlPostgreSQLVersion>
     <CodeAnalysisRuleSet>$(SolutionDir)CodingGuidelines.ruleset</CodeAnalysisRuleSet>
   </PropertyGroup>
 

src/JsonApiDotNetCore/Queries/Internal/QueryableBuilding/SelectClauseBuilder.cs

@@ -133,7 +133,13 @@ private ICollection<PropertySelector> ToPropertySelectors(IDictionary<ResourceFi
             foreach (EagerLoadAttribute eagerLoad in resourceContext.EagerLoads)
             {
                 var propertySelector = new PropertySelector(eagerLoad.Property);
-                propertySelectors[propertySelector.Property] = propertySelector;
+
+                // When an entity navigation property is decorated with both EagerLoadAttribute and RelationshipAttribute,
+                // it may already exist with a sub-layer. So do not overwrite in that case.
+                if (!propertySelectors.ContainsKey(propertySelector.Property))
+                {
+                    propertySelectors[propertySelector.Property] = propertySelector;
+                }
             }
 
             return propertySelectors.Values;

test/JsonApiDotNetCoreExampleTests/IntegrationTests/Issue988/Engagement.cs

@@ -0,0 +1,34 @@
+using System;
+using System.Collections.Generic;
+using System.ComponentModel.DataAnnotations.Schema;
+using System.Linq;
+using JetBrains.Annotations;
+using JsonApiDotNetCore.Resources.Annotations;
+
+namespace JsonApiDotNetCoreExampleTests.IntegrationTests.Issue988
+{
+    [UsedImplicitly(ImplicitUseTargetFlags.Members)]
+    public sealed class Engagement : EntityBase<Guid>
+    {
+        // Data
+
+        [Attr]
+        public string Name { get; set; }
+
+        // Navigation Properties
+
+        [HasMany]
+        [EagerLoad]
+        public ICollection<EngagementParty> Parties { get; set; } //= new List<EngagementParty>();
+
+        [HasMany]
+        [NotMapped]
+        public ICollection<EngagementParty> FirstParties =>
+            Parties.Where(party => party.Role == ModelConstants.FirstPartyRoleName).OrderBy(party => party.ShortName).ToList();
+
+        [HasMany]
+        [NotMapped]
+        public ICollection<EngagementParty> SecondParties =>
+            Parties.Where(party => party.Role == ModelConstants.SecondPartyRoleName).OrderBy(party => party.ShortName).ToList();
+    }
+}

test/JsonApiDotNetCoreExampleTests/IntegrationTests/Issue988/EngagementPartiesController.cs

@@ -0,0 +1,16 @@
+using System;
+using JsonApiDotNetCore.Configuration;
+using JsonApiDotNetCore.Controllers;
+using JsonApiDotNetCore.Services;
+using Microsoft.Extensions.Logging;
+
+namespace JsonApiDotNetCoreExampleTests.IntegrationTests.Issue988
+{
+    public sealed class EngagementPartiesController : JsonApiController<EngagementParty, Guid>
+    {
+        public EngagementPartiesController(IJsonApiOptions options, ILoggerFactory loggerFactory, IResourceService<EngagementParty, Guid> resourceService)
+            : base(options, loggerFactory, resourceService)
+        {
+        }
+    }
+}

test/JsonApiDotNetCoreExampleTests/IntegrationTests/Issue988/EngagementParty.cs

@@ -0,0 +1,25 @@
+using System;
+using JetBrains.Annotations;
+using JsonApiDotNetCore.Resources.Annotations;
+
+namespace JsonApiDotNetCoreExampleTests.IntegrationTests.Issue988
+{
+    [UsedImplicitly(ImplicitUseTargetFlags.Members)]
+    public sealed class EngagementParty : EntityBase<Guid>
+    {
+        // Data (simplified)
+
+        [Attr]
+        public string Role { get; set; }
+
+        [Attr]
+        public string ShortName { get; set; }
+
+        // Foreign Keys (simplified)
+
+        [HasOne]
+        public Engagement Engagement { get; set; }
+
+        //public Guid EngagementId { get; set; }
+    }
+}

test/JsonApiDotNetCoreExampleTests/IntegrationTests/Issue988/EngagementPartyResourceDefinition.cs

@@ -0,0 +1,34 @@
+using System;
+using System.ComponentModel;
+using JetBrains.Annotations;
+using JsonApiDotNetCore.Configuration;
+using JsonApiDotNetCore.Queries.Expressions;
+using JsonApiDotNetCore.Resources;
+
+namespace JsonApiDotNetCoreExampleTests.IntegrationTests.Issue988
+{
+    [UsedImplicitly(ImplicitUseKindFlags.InstantiatedNoFixedConstructorSignature)]
+    public sealed class EngagementPartyResourceDefinition : JsonApiResourceDefinition<EngagementParty, Guid>
+    {
+        /// <inheritdoc />
+        public EngagementPartyResourceDefinition(IResourceGraph resourceGraph)
+            : base(resourceGraph)
+        {
+        }
+
+        /// <inheritdoc />
+        public override SortExpression OnApplySort(SortExpression existingSort)
+        {
+            if (existingSort != null)
+            {
+                return existingSort;
+            }
+
+            return CreateSortExpressionFromLambda(new PropertySortOrder
+            {
+                (ep => ep.Role, ListSortDirection.Ascending),
+                (ep => ep.ShortName, ListSortDirection.Ascending)
+            });
+        }
+    }
+}

test/JsonApiDotNetCoreExampleTests/IntegrationTests/Issue988/EngagementsController.cs

@@ -0,0 +1,16 @@
+using System;
+using JsonApiDotNetCore.Configuration;
+using JsonApiDotNetCore.Controllers;
+using JsonApiDotNetCore.Services;
+using Microsoft.Extensions.Logging;
+
+namespace JsonApiDotNetCoreExampleTests.IntegrationTests.Issue988
+{
+    public sealed class EngagementsController : JsonApiController<Engagement, Guid>
+    {
+        public EngagementsController(IJsonApiOptions options, ILoggerFactory loggerFactory, IResourceService<Engagement, Guid> resourceService)
+            : base(options, loggerFactory, resourceService)
+        {
+        }
+    }
+}

test/JsonApiDotNetCoreExampleTests/IntegrationTests/Issue988/EntityBase.cs

@@ -0,0 +1,18 @@
+using System;
+using System.ComponentModel.DataAnnotations;
+using JetBrains.Annotations;
+using JsonApiDotNetCore.Resources;
+
+namespace JsonApiDotNetCoreExampleTests.IntegrationTests.Issue988
+{
+    [UsedImplicitly(ImplicitUseTargetFlags.Members)]
+    public abstract class EntityBase<TId> : Identifiable<TId>
+    {
+        public DateTimeOffset? DateCreated { get; set; }
+
+        public DateTimeOffset? DateModified { get; set; }
+
+        [Timestamp]
+        public byte[] RowVersion { get; set; }
+    }
+}

test/JsonApiDotNetCoreExampleTests/IntegrationTests/Issue988/IssueDbContext.cs

@@ -0,0 +1,28 @@
+using JetBrains.Annotations;
+using Microsoft.EntityFrameworkCore;
+
+// @formatter:wrap_chained_method_calls chop_always
+
+namespace JsonApiDotNetCoreExampleTests.IntegrationTests.Issue988
+{
+    [UsedImplicitly(ImplicitUseTargetFlags.Members)]
+    public sealed class IssueDbContext : DbContext
+    {
+        public DbSet<Engagement> Engagements { get; set; }
+        public DbSet<EngagementParty> EngagementParties { get; set; }
+
+        public IssueDbContext(DbContextOptions<IssueDbContext> options)
+            : base(options)
+        {
+        }
+
+        protected override void OnModelCreating(ModelBuilder builder)
+        {
+            builder.Entity<EngagementParty>()
+                .HasOne(engagementParty => engagementParty.Engagement)
+                .WithMany(engagement => engagement.Parties)
+                .IsRequired()
+                .OnDelete(DeleteBehavior.Restrict);
+        }
+    }
+}

test/JsonApiDotNetCoreExampleTests/IntegrationTests/Issue988/IssueFakers.cs

@@ -0,0 +1,26 @@
+using System;
+using Bogus;
+using TestBuildingBlocks;
+
+// @formatter:wrap_chained_method_calls chop_always
+// @formatter:keep_existing_linebreaks true
+
+namespace JsonApiDotNetCoreExampleTests.IntegrationTests.Issue988
+{
+    internal sealed class IssueFakers : FakerContainer
+    {
+        private readonly Lazy<Faker<Engagement>> _lazyEngagementFaker = new Lazy<Faker<Engagement>>(() =>
+            new Faker<Engagement>()
+                .UseSeed(GetFakerSeed())
+                .RuleFor(engagement => engagement.Name, faker => faker.Lorem.Word()));
+
+        private readonly Lazy<Faker<EngagementParty>> _lazyEngagementPartyFaker = new Lazy<Faker<EngagementParty>>(() =>
+            new Faker<EngagementParty>()
+                .UseSeed(GetFakerSeed())
+                .RuleFor(party => party.Role, faker => faker.Lorem.Word())
+                .RuleFor(party => party.ShortName, faker => faker.Lorem.Word()));
+
+        public Faker<Engagement> Engagement => _lazyEngagementFaker.Value;
+        public Faker<EngagementParty> EngagementParty => _lazyEngagementPartyFaker.Value;
+    }
+}