ASP.NET MVC：字段存在，但验证错误显示"Field is required"

Question

摘要：

当我想在数据库中更新模型实例时，它会导致验证错误Field is required Client字段（在保存之前填充Altough字段，并且在我跟踪程序时并不为空）。

详细信息：

我有一个模型Project，如下所示：

namespace ProjectManager.Models
{
    public class Project
    {
        [Key]
        public int Id { get; set; }
        [Required]
        [Display(Name = "نام پروژه")]
        [StringLength(100, MinimumLength = 5, ErrorMessage = "{0} باید حداقل {2} و حداکثر {1} کاراکتری باشد")]
        public string Name { get; set; }
        [Display(Name = "کارفرما")]
        [Required]
        public virtual ApplicationUser Client { get; set; }
        [ForeignKey("Client")]
        public string ClientId{ get; set; }

        [Display(Name = "مدیر پروژه")]
        [Required]
        public virtual ApplicationUser ProjectManager { get; set; }
        [ForeignKey("ProjectManager")]
        public string ProjectManagerId{ get; set; }
        [Range(0,100)]
        [Display(Name = "پیشرفت پروژه")]
        [Required]
        public int Progress { get; set; }
        [DataType(DataType.Date)]
        [Display(Name = "تاریخ ثبت پروژه")]
        [DisplayFormat(DataFormatString = "{0:yyyy-MM-dd}", ApplyFormatInEditMode = true)]
        public DateTime CreateDate { get; set; }
        //[Required]
        [Column("Disabled")]
        [Display(Name = "غیرفعال")]
        public bool Disabled{ get; set; }
        //[Required]
        [Column("Status")]
        [Display(Name = "وضعیت")]
        public string Status{ get; set; }
        //-------------------- Payment Requests of Projects
        public virtual ICollection<PaymentRequest> PaymentRequests { get; set; }
        public virtual ICollection<Contract> Contracts { get; set; }
    }
}

当我想更改项目进度时，我会使用以下控制器：

    public ActionResult UpdateProgress()
    {
        ApplicationUser projectManager = db.Users.Find(User.Identity.GetUserId());
        Project project = Utils.getProjectManagerProject(projectManager, db);
        EditProgressProjectViewModel model = new EditProgressProjectViewModel
        {
            Progress = project.Progress
        };
        return View(model);
    }
    [HttpPost]
    [ValidateAntiForgeryToken]
    public ActionResult UpdateProgress(EditProgressProjectViewModel projectModel)
    {
        if (projectModel == null)
            return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
        if (ModelState.IsValid)
        {
            ApplicationUser projectManager = db.Users.Find(User.Identity.GetUserId());
            Project project = Utils.getProjectManagerProject(projectManager, db);
            project.Progress = projectModel.Progress;
            try
            {
                db.SaveChanges();
            }
            catch (DbEntityValidationException e)
            {
                Utils.addValidationErrorsToModelState(ModelState, e);
                return View(projectModel);
            }
            return RedirectToAction("Index");
        }
        return View(projectModel);
    }
}

但是尝试运行db.savechanges（）导致验证错误，这些错误说" field client是必需的"，但是project.client并不为空，并且已经从数据库中获取的值填充。

Answer 1

问题是 [Required]定义在坏处，这意味着而不是此声明：

    [Display(Name = "کارفرما")]
    [Required]
    public virtual ApplicationUser Client { get; set; }
    [ForeignKey("Client")]
    public string ClientId{ get; set; }

必须使用：

    [Display(Name = "کارفرما")]
    public virtual ApplicationUser Client { get; set; }
    [ForeignKey("Client")]
    [Required] //**** Right Place for required annotation****
    public string ClientId{ get; set; }

[Required]应该放置用于ForeignKey ID而不是ForeignKey对象。