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Question

晚上好。

我正在构建一个用于项目管理的小型Web API。

每个项目都分为许多任务。

最终我尝试从Task对象（slave）访问Project对象（master），但是GET请求（在Task上）没有通过postman响应或者通过chrome得到不完整的响应，就像这样：

GET / api / task / 1：

{
"id": 1,
"name": "Task A",
"description": "Primary task",
"priority": 0,
"state": 0,
"projectId": 1,
"project": {
    "id": 1,
    "name": "Project 1",
    "description": "First project",
    "deadline": "0001-01-01T00:00:00",
    "clientId": 0,
    "tasks": [

我将介绍模型，上下文和控制器类，我希望得到如何正确指示EF以包含与任务中的外键字段对应的Project对象的帮助。

以下是Project模型的类：

//Project.cs:

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;

namespace ProjectManagementAPI.Models
{
    public class Project
    {
        public Project()
        {
            Tasks = new List<Task>();
        }

        public int Id { get; set; }
        public String Name { get; set; }
        public String Description { get; set; }
        public DateTime Deadline { get; set; }
        public int ClientId { get; set; }
        public ICollection<Task> Tasks { get; set; }
    }
}

对于任务：

//Task.cs

namespace ProjectManagementAPI.Models
{
    public enum STATE { Pending, Started, Blocked, Finished }

    public class Task
    {
        public Task()
        {
        }
        public int Id { get; set; }
        public String Name { get; set; }
        public String Description { get; set; }
        public int Priority { get; set; }
        public STATE State { get; set; }

        [ForeignKey("ProjectId")]
        public int ProjectId { get; set; }
        public Project Project { get; set; }
    }
}

Context类通过Fluent API详细说明了该关系：

//ProjectManagementDBEntities.cs

namespace ProjectManagementAPI.Models
{
    public class ProjectManagementDBEntities : DbContext
    {
        public ProjectManagementDBEntities(DbContextOptions<ProjectManagementDBEntities> options)
            : base(options)
        {
        }

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            modelBuilder.Entity<Task>()
                .HasOne(p => p.Project)
                .WithMany(b => b.Tasks)
                .OnDelete(DeleteBehavior.Cascade);
        }

        public DbSet<Project> Projects { get; set; }
        public DbSet<Task> Tasks { get; set; }
    }
}

项目控制器类（省略更新和删除控件）：

//ProjectController.cs

namespace ProjectManagementAPI.Controllers
{
    [Route("api/[controller]")]
    public class ProjectController : Controller
    {
        private readonly ProjectManagementDBEntities _context;

        public ProjectController(ProjectManagementDBEntities context)
        {
            _context = context;

        }

        [HttpGet]
        public IEnumerable<Project> GetAll()
        {
            return _context.Projects.ToList();
        }


        [HttpGet("{id}", Name = "GetProject")]
        public IActionResult GetById(long id)
        {
            var project = _context.Projects.FirstOrDefault(t => t.Id == id);
            if (project == null)
            {
                return NotFound();
            }
            return new ObjectResult(project);
        }

        [HttpPost]
        public IActionResult Create([FromBody] Project project)
        {
            if (project == null)
            {
                return BadRequest();
            }
            project.Tasks = new List<Task>();

            _context.Projects.Add(project);
            _context.SaveChanges();

            return CreatedAtRoute("GetProject", new { id = project.Id }, project);
        }
}

在Task控制器中，我使用LINQ的Include（）方法来请求对象的预先加载。我怀疑它是错误所在的地方。

//TaskController.cs

namespace ProjectManagementAPI.Controllers
{
    [Route("api/[controller]")]
    public class TaskController : Controller
    {
        private readonly ProjectManagementDBEntities _context;

        public TaskController(ProjectManagementDBEntities context)
        {
            _context = context;

        }

        [HttpGet]
        public IEnumerable<Task> GetAll()
        {
            return _context.Tasks.Include(t => t.Project).ToList();
        }


        [HttpGet("{id}", Name = "GetTask")]
        public IActionResult GetById(long id)
        {
            var task = _context.Tasks.Include(t => t.Project).FirstOrDefault(t => t.Id == id);
            if (task == null)
            {
                return NotFound();
            }
            return new ObjectResult(task);
        }

        [HttpPost]
        public IActionResult Create([FromBody] Task Task)
        {
            if (Task == null)
            {
                return BadRequest();
            }

            _context.Tasks.Add(Task);
            _context.SaveChanges();

            return CreatedAtRoute("GetTask", new { id = Task.Id }, Task);
        }
}

谢谢。