Answer issue 1539

src/Examples/GettingStarted/Controllers/BooksController.cs

@@ -0,0 +1,14 @@
+using GettingStarted.Models;
+using JsonApiDotNetCore.Configuration;
+using JsonApiDotNetCore.Controllers;
+using JsonApiDotNetCore.Services;
+
+namespace GettingStarted.Controllers;
+
+public sealed class BooksController : JsonApiController<Book, string?>
+{
+    public BooksController(IJsonApiOptions options, ILoggerFactory loggerFactory, IResourceService<Book, string?> resourceService)
+        : base(options, loggerFactory, resourceService)
+    {
+    }
+}

src/Examples/GettingStarted/Definitions/BooksDefinition.cs

@@ -0,0 +1,31 @@
+using GettingStarted.Models;
+using JsonApiDotNetCore.Configuration;
+using JsonApiDotNetCore.Queries.Expressions;
+using JsonApiDotNetCore.QueryStrings;
+using JsonApiDotNetCore.Resources;
+
+namespace GettingStarted.Definitions;
+
+public sealed class BooksDefinition : JsonApiResourceDefinition<Book, string?>
+{
+    private readonly IRequestQueryStringAccessor _queryStringAccessor;
+
+    public BooksDefinition(IResourceGraph resourceGraph, IRequestQueryStringAccessor queryStringAccessor)
+        : base(resourceGraph)
+    {
+        _queryStringAccessor = queryStringAccessor;
+    }
+
+    public override SparseFieldSetExpression? OnApplySparseFieldSet(SparseFieldSetExpression? existingSparseFieldSet)
+    {
+        if (!_queryStringAccessor.Query.ContainsKey("fields[books]"))
+        {
+            return existingSparseFieldSet
+                .Excluding<Book>(book => book.Refs1, ResourceGraph)
+                .Excluding<Book>(book => book.Refs2, ResourceGraph)
+                .Excluding<Book>(book => book.Refs3, ResourceGraph);
+        }
+
+        return existingSparseFieldSet;
+    }
+}

src/Examples/GettingStarted/GettingStarted.csproj

@@ -1,11 +1,11 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
   <PropertyGroup>
-    <TargetFrameworks>net8.0;net6.0</TargetFrameworks>
+    <TargetFrameworks>net6.0</TargetFrameworks>
   </PropertyGroup>
 
   <Import Project="..\..\..\package-versions.props" />
 
   <ItemGroup>
-    <ProjectReference Include="..\..\JsonApiDotNetCore.MongoDb\JsonApiDotNetCore.MongoDb.csproj" />
+    <PackageReference Include="JsonApiDotNetCore.MongoDb" Version="4.2.0-alpha1" />
   </ItemGroup>
 </Project>

src/Examples/GettingStarted/Models/Book.cs

@@ -5,8 +5,7 @@
 namespace GettingStarted.Models;
 
 [UsedImplicitly(ImplicitUseTargetFlags.Members)]
-[Resource]
-public sealed class Book : HexStringMongoIdentifiable
+public sealed class Book : MongoIdentifiable
 {
     [Attr]
     public string Title { get; set; } = null!;
@@ -16,4 +15,13 @@ public sealed class Book : HexStringMongoIdentifiable
 
     [Attr]
     public int PublishYear { get; set; }
+
+    [Attr]
+    public List<string>? Refs1 { get; set; }
+
+    [Attr]
+    public List<string>? Refs2 { get; set; }
+
+    [Attr]
+    public List<string>? Refs3 { get; set; }
 }

src/Examples/GettingStarted/Program.cs

@@ -1,9 +1,11 @@
+using GettingStarted.Definitions;
 using GettingStarted.Models;
 using JsonApiDotNetCore.Configuration;
 using JsonApiDotNetCore.MongoDb.Configuration;
 using JsonApiDotNetCore.MongoDb.Repositories;
 using Microsoft.Extensions.DependencyInjection.Extensions;
 using MongoDB.Driver;
+using Newtonsoft.Json;
 
 WebApplicationBuilder builder = WebApplication.CreateBuilder(args);
 
@@ -19,6 +21,7 @@
 builder.Services.AddJsonApiMongoDb();
 
 builder.Services.AddResourceRepository<MongoRepository<Book, string?>>();
+builder.Services.AddResourceDefinition<BooksDefinition>();
 
 WebApplication app = builder.Build();
 
@@ -38,7 +41,7 @@ static void ConfigureJsonApiOptions(JsonApiOptions options)
     options.Namespace = "api";
     options.UseRelativeLinks = true;
     options.IncludeTotalResourceCount = true;
-    options.SerializerOptions.WriteIndented = true;
+    options.SerializerSettings.Formatting = Formatting.Indented;
 }
 
 static async Task CreateSampleDataAsync(IMongoDatabase database)

src/Examples/GettingStarted/Properties/launchSettings.json

@@ -11,15 +11,15 @@
     "IIS Express": {
       "commandName": "IISExpress",
       "launchBrowser": true,
-      "launchUrl": "api/books",
+      "launchUrl": "api/books?fields[books]=title,refs1,refs2",
       "environmentVariables": {
         "ASPNETCORE_ENVIRONMENT": "Development"
       }
     },
     "Kestrel": {
       "commandName": "Project",
       "launchBrowser": true,
-      "launchUrl": "api/books",
+      "launchUrl": "api/books?fields[books]=title,refs1,refs2",
       "applicationUrl": "http://localhost:24141",
       "environmentVariables": {
         "ASPNETCORE_ENVIRONMENT": "Development"