更新值提供商之前TryUpdateModel [英] Updating value provider prior to TryUpdateModel
问题描述
假设我们有一个叫做PetsName属性的类。如果是空白的屏幕上我想因此，如果用户没有输入一个小名，我们强迫'无名'，以更新的价值提供者。这不是实际情况..这当然是一个样的，所以像网页上，只等设置默认值的答案将不适合这样的场景：）
Lets say we have a class with a property called PetsName. If it is left blank on the screen I want to update the value provider so if the user doesn't enter a pet name, we force 'unnamed'. This isn't the actual scenario.. this is of course a sample, so answers like 'just set default values on a webpage, etc' won't fit this scenario : )
主要的问题是，我们希望在更新它会使用该模型无论你已经覆盖到更新值左右。我想一个想法是要删除值和添加。当我检查的ModelState，它确实有更新的价值，但是当我打电话TryUpdateModel，值不会被更新。它可能什么IM下面做的是确实是正确的并且这里还有另外一个问题，但我想我会尝试这第一次。谢谢！
The main issue is we want to update the values so when you update the model it will use whatever you have overridden. I guess one idea is to remove the value and add it. When I check ModelState, it does have the updated value, however when I call TryUpdateModel, the value is not updated. Its possible what Im doing below is indeed correct and there is another issue here but I figured I'd try this first. Thanks!
//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
}
推荐答案
幕后真正的问题在这里的是，Html.HiddenFor没有显示即使TryUpdateModel在模型更新的价值给予了正确的值视图。
The real issue behind the scenes here is that Html.HiddenFor wasn't displaying the correct value even though TryUpdateModel was updating a value in the model to give to the view.
这里的问题是，HTML辅助假设，如果您呈现一个帖子后认为，有mustve是一个错误（否则你wouldve重定向回用GET方法的观点 - 因此后重定向获取问题）
The issue here is that the Html helpers assume if you are rendering a view after a post, there mustve been an error (otherwise you wouldve redirected back to the view with a GET method - hence the Post Redirect Get issue)
这是在细节，请
<一href=\"http://blogs.msdn.com/b/simonince/archive/2010/05/05/asp-net-mvc-s-html-helpers-render-the-wrong-value.aspx\" rel=\"nofollow\">http://blogs.msdn.com/b/simonince/archive/2010/05/05/asp-net-mvc-s-html-helpers-render-the-wrong-value.aspx
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