麻烦路过视图和控制器之间复杂的数据在ASP.NET MVC [英] Trouble passing complex data between view and controller in ASP.NET MVC

问题描述

下面是我在ASP.NET MVC模型真正的简化，我认为这将有助于集中在问题：

Here's a simplification of my real models in ASP.NET MVC, that I think will help focus in on the problem:

让我们说我有两个域对象：

Let's say I have these two domain objects:

public class ObjectA
{
    public ObjectB ObjectB;
}

public class ObjectB
{
}

我也有一种观点认为，可以让我创建一​​个新的对象A和包括从可能ObjectBs列表中选择一个对象B

I also have a view that will allow me to create a new ObjectA and that includes selecting one ObjectB from a list of possible ObjectBs.

我创建了一个新类的可能性，这个名单来装饰对象A，这真的是我的视图模型，我猜。

I have created a new class to decorate ObjectA with this list of possibilities, this is really my view model I guess.

public class ObjectAViewModel
{
    public ObjectA ObjectA { get; private set; }
    public SelectList PossibleSelectionsForObjectB { get; private set; }

    public ObjectAViewModel(ObjectA objectA, IEnumerable<Location> possibleObjectBs)
    {
        ObjectA = objectA;
        PossibleSelectionsForObjectB = new SelectList(possibleObjectBs, ObjectA.ObjectB);
    }
}

现在，什么是构建我的视图和控制器允许用户在视图中选择一个对象B，然后让控制器保存对象A与对象B的选择（对象B已经存在，并保存）的最佳方法是什么？

Now, what is the best way to construct my view and controller to allow a user to select an ObjectB in the view, and then have the controller save ObjectA with that ObjectB selection (ObjectB already exists and is saved)?

我试图创建一个类型，ObjectAViewModel的强类型的视图，并绑定Html.DropDownList到Model.PossibleSelectionsForObjectB。这是好的，而且我可以选择的对象就好了。但要回控制器是我在哪里挣扎。

I tried creating a strongly-typed view of type, ObjectAViewModel, and binding a Html.DropDownList to the Model.PossibleSelectionsForObjectB. This is fine, and the I can select the object just fine. But getting it back to the controller is where I am struggling.

尝试性解决方案1：

[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Create(ObjectAViewModel objectAViewModel)

这里此问题在于objectAViewModel.ObjectA.ObjectB属性为空。我想这势必将这个属性DropDownList中，将更新，当用户在视图中选择此模式，但它不是出于某种原因。

This problem here is that the objectAViewModel.ObjectA.ObjectB property is null. I was thinking the DropDownList which is bound to this property, would update the model when the user selected this in the view, but it's not for some reason.

尝试性解决方案2：

[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Create(ObjectA objectA)

这里此问题在于ObjectA.ObjectB属性为空。再次，我想也许DropDownList的选择会更新此。

This problem here is that the ObjectA.ObjectB property is null. Again, I thought maybe the DropDownList selection would update this.

我也使用在上述各方案的的UpdateModel方法，没有运气试过。没有任何人有什么想法？我猜我缺少一个绑定或一些地方...

I have also tried using the UpdateModel method in each of the above solutions, with no luck. Does anyone have any ideas? I'm guessing I'm missing a binding or something somewhere...

谢谢！

推荐答案

一些调查研究后，它看起来并不像这是一个情况下，ASP.NET MVC会照顾我。或许有一个数据服务绑定模式，我可以使用（所以MVC会自动抓取合适的对象了内存，基于什么在下拉列表中选择），但现在，我可以在控制器处理起来解决这个问题：

After some more research it doesn't look like this is a case ASP.NET MVC will take care of for me. Perhaps there is a data service binding model I can use (so MVC would automatically grab the appropriate object out of memory, based on what was selected in the dropdown), but for now, I can fix this by handling it in the controller:

1. 从使用Controller.ModelState下拉获取所选择的项目


2. 重新装入对象B从底层数据服务


3. 分配的对象B到ObjectA.ObjectB


4. 保存对象A

所以我的控制器方法看起来现在这​​个样子：

So my controller method looks like this now:

根据来自LukLed评论主编

   [AcceptVerbs(HttpVerbs.Post)]
    public ActionResult Create(ObjectA objectA, string objectBStr)
    {
        ObjectB objectB = _objBService.Get(objectBStr);
        objectA.ObjectB = objectB;
        _objAService.Save(objectA);
        return RedirectToAction("Details", new { id = objectA.Id });
    }

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