在TryUpdateModel之前更新值提供程序

时间:2010-08-23 03:56:58

标签: asp.net-mvc modelstate

假设我们有一个名为PetsName的类。如果它在屏幕上留空,我想更新值提供者,所以如果用户没有输入宠物名称,我们强制“未命名”。这不是实际场景..这当然是一个示例,所以像“只是在网页上设置默认值等”的答案将不适合这种情况:)

主要问题是我们想要更新值,因此当您更新模型时,它将使用您覆盖的任何内容。我想一个想法是删除值并添加它。当我检查ModelState时,它确实具有更新的值,但是当我调用TryUpdateModel时,该值不会更新。它可能我在下面做的确实是正确的,这里还有另一个问题,但我想我先试试这个。谢谢!

    //Sample case:

    [HttpPost]
    public ActionResult Edit(PetOwner petOwner)
    {

    //If pets name is not set, force to "Unknown"
    if(petOwner.PetsName=="")
    {
    //Tried this too ModelState.Remove("PetsName");
    //ModelState.Add("PetsName", new ModelState());
    ModelState["PetsName"].Value = new ValueProviderResult("Unnamed", "Unnamed", CultureInfo.CurrentCulture);
    }

    //Get the record/relationships from DB to merge with ModelState
    PetOwner petOwnerToSave = from o in ctx.PetOwners where o.PetOwnerId == petOwner.PetOwnerId select o;

    TryUpdateModel(petOwnerToSave);

    //Save petOwnerToSave
    }

//Sample case: [HttpPost] public ActionResult Edit(PetOwner petOwner) { //If pets name is not set, force to "Unknown" if(petOwner.PetsName=="") { //Tried this too ModelState.Remove("PetsName"); //ModelState.Add("PetsName", new ModelState()); ModelState["PetsName"].Value = new ValueProviderResult("Unnamed", "Unnamed", CultureInfo.CurrentCulture); } //Get the record/relationships from DB to merge with ModelState PetOwner petOwnerToSave = from o in ctx.PetOwners where o.PetOwnerId == petOwner.PetOwnerId select o; TryUpdateModel(petOwnerToSave); //Save petOwnerToSave }

1 个答案:

答案 0 :(得分:4)

这背后的真正问题是Html.HiddenFor没有显示正确的值,即使TryUpdateModel正在更新模型中的值以提供给视图。

这里的问题是Html助手假设你在帖子之后渲染一个视图,一定是一个错误(否则你会用GET方法重定向回到视图 - 因此Post Redirect Get问题)

详细描述如下: http://blogs.msdn.com/b/simonince/archive/2010/05/05/asp-net-mvc-s-html-helpers-render-the-wrong-value.aspx