绑定到ViewModel时如何更新Model? [英] How to update Model when binding to a ViewModel?
问题描述
我有一个[HttpPost]动作方法签名，如下所示:
I have an [HttpPost] action method signature like this:
[HttpPost]
public ActionResult Edit(ExistingPostViewModel model)
{
// Save the edited Post.
}
现在，在过去(当我不使用ViewModels时，例如R& D)，我实现了这样的 Edit 方法的实现:
Now, in the past (when i didn't use ViewModels, e.g R&D), i had an implementation of an Edit method like this:
[HttpPost]
public ActionResult Edit(Post model)
{
var existingPost = repo.Find(model.Id);
TryUpdateModel(existingPost);
repo.Save(existingPost);
return RedirectToAction("Success", existingPost.Id);
}
哪个做得很棒.
但是我很困惑如何使以上内容适应ViewModel方法.
But i'm confused how to adapt the above to the ViewModel approach.
如果我这样做:
TryUpdateModel(existingPost)
使用我的ViewModel方法，发生的事情很少.没有错误，但是没有任何更新，因为MVC不知道如何从ExistingPostViewModel(在Post-> Post之前)更新Post.
With my ViewModel approach, not much happens. No errors, but nothing is being updated because MVC won't know how to update a Post from a ExistingPostViewModel (before it was Post -> Post).
现在，我正在使用AutoMapper.所以我想我可以从ViewModel映射到Post，然后保存帖子.
Now, i'm using AutoMapper. So i thought i could map from the ViewModel to the Post, then save the post.
但是我基本上是覆盖了一切.我不想这样做，并打败了削减ViewModel的观点.
But then im basically overriding everything. Which i don't want to do and defeats the point of the cut down ViewModel.
任何人都可以使我困惑吗?
Can anyone un-confuse me?
这似乎是一个非常普遍的情况，对于人们如何解决这个问题我深感困惑.我只能看到3种可能的解决方案:
This seems like a really common scenario, and i am totally stumped as to how people solve this. I can only see 3 possible solutions:
-
不要在HTTP POST中使用ViewModel.就像我说的那样，过去我曾为R& D进行过此操作，但它确实有效，但是现在我看到了View的发展方式(验证，简单性)，我不能为了这个问题而妥协.
Don't use a ViewModel in the HTTP POST. As i said i did this in the past for R&D and it works, but now i see how my View's have evolved (validation, simplicity), and i can't compromise that just for the sake of this problem.
不要使用TryUpdateModel.可能，但是那我将如何合并更改?
Don't use TryUpdateModel. Possibly, but then how would i merge in the changes?
从左到右使用.啊.但目前看来，这似乎是我的追求方式.
Use left-to-right. Ugh. But at the moment this seems to be the way im leaning.
有人请给我解决方案4！ :)
Someone please give me solution #4! :)
顺便说一句，我正在使用ASP.NET MVC 3，Razor和实体框架.
BTW, i'm using ASP.NET MVC 3, Razor and Entity Framework.
推荐答案
我实际上在当前正在研究的项目中遇到了这个完全相同的问题.尽管我不喜欢它，但最终还是采取了从左到右的方法，并将视图模型数据手动映射回我的实体.
I actually ran into this exact same issue in a project I'm currently working on. As much as I wasn't a fan of it, I ended up doing the left to right approach and manually mapping my viewmodel data back to my entity.
此方法的唯一好处是，它确实可以为您提供更多控制权.自从我开始使用更多的复合视图模型(实际上，您在视图模型中拥有多个实体的字段)以来，以这种方式进行操作就变得更加有意义.
The only nice thing about this approach is it does give you more control. Since I started using more compound viewmodels, where you actually have fields from more than one entity in your viewmodel, it started making more sense to do things this way.
我也在使用AutoMapper，你是完全正确的，当您尝试执行简单的更新操作时，它确实变得笨拙.希望我能为您提供一些超级聪明的解决方法，但是老式方式"似乎可以使我所做的工作最好地完成.
I'm also using AutoMapper, and you're absolutely right, it does get awkward when you're trying to do a simple update operation. Wish I had some super clever workaround for you, but the "old fashioned way" seems to get the job done best for the work I've been doing.
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