add coursestudent resource corresponding to the coursestudent many-to-many entity required by ef core

Author: roblankey

src/Examples/JsonApiDotNetCoreExample/Migrations/20180717134637_ResourceSeparation.cs

@@ -61,6 +61,8 @@ protected override void Up(MigrationBuilder migrationBuilder)
                 name: "CourseStudent",
                 columns: table => new
                 {
+                    Id = table.Column<int>(nullable: false)
+                        .Annotation("Npgsql:ValueGenerationStrategy", NpgsqlValueGenerationStrategy.SerialColumn),
                     courseid = table.Column<int>(name: "course_id", nullable: false),
                     studentid = table.Column<int>(name: "student_id", nullable: false)
                 },
@@ -82,14 +84,19 @@ protected override void Up(MigrationBuilder migrationBuilder)
                 });
 
             migrationBuilder.CreateIndex(
-                name: "IX_Course_department-id",
+                name: "IX_Course_department_id",
                 table: "Course",
                 column: "department_id");
 
             migrationBuilder.CreateIndex(
-                name: "IX_CourseStudent_student-id",
+                name: "IX_CourseStudent_student_id",
                 table: "CourseStudent",
                 column: "student_id");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_CourseStudent_Id",
+                table: "CourseStudent",
+                column: "Id");
         }
 
         protected override void Down(MigrationBuilder migrationBuilder)

src/Examples/JsonApiDotNetCoreExample/Models/Entities/CourseStudentEntity.cs

@@ -1,10 +1,11 @@
+using JsonApiDotNetCore.Models;
 using Microsoft.EntityFrameworkCore.Infrastructure;
 using System.ComponentModel.DataAnnotations.Schema;
 
 namespace JsonApiDotNetCoreExample.Models.Entities
 {
     [Table("CourseStudent")]
-    public class CourseStudentEntity
+    public class CourseStudentEntity : Identifiable
     {
         private CourseEntity _course;
         private StudentEntity _student;

src/Examples/JsonApiDotNetCoreExample/Models/Resources/CourseStudentResource.cs

@@ -0,0 +1,23 @@
+using JsonApiDotNetCore.Models;
+
+namespace JsonApiDotNetCoreExample.Models.Resources
+{
+    /// <summary>
+    /// Note: EF Core *requires* the creation of an additional entity
+    /// for many to many relationships and no longer implicitly creates
+    /// it. While it may not make sense to create a corresponding "resource"
+    /// for that relationship, due to the need to make the underlying 
+    /// framework and mapping understand the explicit navigation entity, 
+    /// a mirroring DTO resource is also required.
+    /// </summary>
+    public class CourseStudentResource : Identifiable
+    {
+        [HasOne("course")]
+        public CourseResource Course { get; set; }
+        public int CourseId { get; set; }
+
+        [HasOne("student")]
+        public StudentResource Student { get; set; }
+        public int StudentId { get; set; }
+    }
+}

src/Examples/ResourceEntitySeparationExample/Startup.cs

@@ -38,9 +38,8 @@ public virtual IServiceProvider ConfigureServices(IServiceCollection services)
             services.AddSingleton<ILoggerFactory>(loggerFactory);
 
             services.AddDbContext<AppDbContext>(options => options
-                .UseNpgsql(GetDbConnectionString())
-                /*.UseLazyLoadingProxies()*/,
-            ServiceLifetime.Transient);
+                .UseNpgsql(GetDbConnectionString()),
+                ServiceLifetime.Transient);
             services.AddScoped<IDbContextResolver, DbContextResolver<AppDbContext>>();
 
             var mvcBuilder = services.AddMvcCore();