Question

我知道asp.net mvc web应用程序中的html帮助程序（如Html.EditorFor Html.TextBoxFor等）会查看表单集合，如果找不到值，它将使用模型值，除非调用{{ 1}}但现在我有以下post edit action方法，我正在检查并发异常： -

modelstate.clear().

我感到困惑的是在异常中使用它： -

[HttpPost]
[ValidateAntiForgeryToken]
public async Task<ActionResult> Edit(Skill skill)
{
  try
  {
    var dbskill = db.Skills.SingleOrDefault(a => a.SkillID == skill.SkillID);
    db.Entry(dbskill).State = EntityState.Detached;
    skill.Created = dbskill.Created;
    skill.Modified = System.DateTime.Now;
    skill.CreatedBy = dbskill.CreatedBy;
    skill.ModifiedBy = staffrepo.GetUserIdByUserName(User.Identity.Name.Substring(User.Identity.Name.IndexOf("\\") + 1));
    skill.DeletedDate = dbskill.DeletedDate;
    skill.IsActive = dbskill.IsActive;
    skill.StatusID = db.SkillStatus.Where(a => a.SkillStatusName.ToLower().StartsWith("pen")).SingleOrDefault().SkillStatusID;
    if (ModelState.IsValid)
    {
      skill.CurrentVersion =  dbskill.CurrentVersion + (Decimal)0.01;
      db.Entry(skill).State = EntityState.Modified;
      await db.SaveChangesAsync();
      return RedirectToAction("Details", new { id =skill.SkillID});
    }
  }        
  catch (DbUpdateConcurrencyException ex)
  {
    var entry = ex.Entries.Single();
    var clientValues = (Skill)entry.Entity;
    var databaseEntry = entry.GetDatabaseValues();
    var databaseValues = (Skill)databaseEntry.ToObject();
    var currentSkillTypename = db.SkillTypes.SingleOrDefault(a => a.SkillTypeID == databaseValues.SkillTypeID).Name;
    var currentSkillStatusname = db.SkillStatus.SingleOrDefault(a => a.SkillStatusID == databaseValues.StatusID).SkillStatusName;
    var currentModifiedByName = db.Staffs.SingleOrDefault(a => a.StaffID == databaseValues.ModifiedBy).SamAccUserName;
    if (databaseEntry == null)
    {
      ModelState.AddModelError(string.Empty, "Unable to save changes. The department was deleted by another user.");
    }
    else
    {              
      if (databaseValues.Name != clientValues.Name)
        ModelState.AddModelError("Name", "Current value: " + databaseValues.Name);

      //code goes here...........
      ModelState.AddModelError(string.Empty, "The record you attempted to edit "
      + "was modified by another user after you got the original value. The "
      + "edit operation was canceled and the current values in the database "
      + "have been displayed. If you still want to edit this record, click "
      + "the Save button again. Otherwise click the Back to List hyperlink.");
      skill.timestamp = databaseValues.timestamp;
    }
  }
  catch (Exception e)
  {
    var c = e;
  }
  //
  return View(skill);
}

现在因为我在视图上使用hiddenfor将时间戳传递给post edit动作方法，所以这意味着skill.timestamp将始终是相同的，因为用户将始终收到并发异常，因为Html。 Hiddenfor将始终从模型中读取值，因此时间戳将始终相同，但发生的事情是在第一次并发异常之后，并且如果用户单击“保存”，则第二次将保存其修改。 ..所以有人可以就此提出建议吗？

Answer 1

默认情况下，值提供程序集合按以下顺序评估各种源的值：

以前绑定的操作参数，当操作是子操作时
表单字段（Request.Form）
JSON请求体（Request.InputStream）中的属性值，但仅当请求是AJAX请求时
路由数据（RouteData.Values）
查询字符串参数（Request.QueryString）
已发布文件（Request.Files）

https://msdn.microsoft.com/en-us/magazine/hh781022.aspx

http://dotnetslackers.com/articles/aspnet/Understanding-ASP-NET-MVC-Model-Binding.aspx

当使用html.hiddenfor时，表单集合优先于模型

1 个答案: