我在 asp.net MVC 3 中创建了一个 CRUD 应用程序。索引页面在表中显示了我数据库中的所有数据。但是,当我单击编辑、详细信息或删除此错误时,我得到:
The parameters dictionary contains a null entry for parameter 'id' of non-nullable type 'System.Int32' for method 'System.Web.Mvc.ActionResult Delete(Int32)' in 'cpd.Controllers.Default4Controller'. An optional parameter must be a reference type, a nullable type, or be declared as an optional parameter.
我有两个类来模拟我的表。我首先使用了代码,下面是我的课程的代码。
public class cpd_certificates
{
[Key]
public int CertificateNo { get; set; }
public int QuizNo { get; set; }
public DateTime? DateReceived { get; set; }
public DateTime? DatePaid { get; set; }
public string Mark { get; set; }
public int? AccreditationNo { get; set; }
public int? ID { get; set; }
public virtual cpd_recipients Recipients { get; set; }
}
public class cpd_recipients
{
[Key]
public int ID { get; set; }
public string OpNo { get; set; }
[Required]
[StringLength(50, ErrorMessage = "{0} cannot exceed {1} characters")]
public string LastName { get; set; }
public string Initials { get; set; }
public string Title { get; set;}
public string Address1 {get; set;}
public string Address2 {get; set;}
public string Address3 {get; set;}
public string Address4 {get; set;}
public string Country {get; set;}
public string email {get; set;}
}
这映射为 0..1 到许多。我的流利的API如下:
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<cpd_certificates>()
.HasOptional(x => x.Recipients);
}
部分控制器代码:
public ActionResult Edit(int id)
{
cpd_certificates cpd_certificates = db.Cert.Find(id);
ViewBag.ID = new SelectList(db.CPD, "ID", "OpNo", cpd_certificates.ID);
return View(cpd_certificates);
}
// POST: /Default4/Edit/5
public ActionResult Edit(cpd_certificates cpd_certificates)
{
if (ModelState.IsValid)
{
db.Entry(cpd_certificates).State = EntityState.Modified;
db.SaveChanges();
return RedirectToAction("Index");
}
ViewBag.ID = new SelectList(db.CPD, "ID", "OpNo", cpd_certificates.ID);
return View(cpd_certificates);
}
视图代码:
@Html.ActionLink("Edit", "Edit", new { /* id=item.PrimaryKey */ }) |
@Html.ActionLink("Details", "Details", new { /* id=item.PrimaryKey */ }) |
@Html.ActionLink("Delete", "Delete", new { /* id=item.PrimaryKey */ })
地图路线:
routes.MapRoute(
"Default", // Route name
"{controller}/{action}/{id}", // URL with parameters
new { controller = "Default4", action = "Index", id = UrlParameter.Optional } // Parameter defaults
);
我该如何解决这个错误。我在这方面比较缺乏经验。