所以我有一个有问题的 MVC Asp.net 应用程序.本质上，我有一个包含表单的视图，其内容绑定到一个对象列表.在这个循环中，它加载 PartialView 和被循环的项目.现在一切正常，直到提交表单.当它被提交时，控制器被发送一个空的对象列表.下面的代码演示了这些问题.
父视图:
@model IEnumerable@using (Html.BeginForm("ComparePlans", "Plans", FormMethod.Post, new { id = "compareForm" })){<div>@foreach(模型中的 var planVM){@Html.Partial("_partialView", planVM)}
so I have an MVC Asp.net app that is having issues. Essentially, I have a View that contains a form, and its contents are bound to a list of objects. Within this loop, it loads PartialView's with the items being looped over. Now everything works up till the submittion of the form. When it gets submitted, the controller is sent a null list of objects. The code below demonstates the problems.
Parent View:
@model IEnumerable<PlanCompareViewModel>
@using (Html.BeginForm("ComparePlans", "Plans", FormMethod.Post, new { id = "compareForm" }))
{
<div>
@foreach (var planVM in Model)
{
@Html.Partial("_partialView", planVM)
}
</div>
}
public class PlansCompareViewModel
{
public int PlanID { get; set; }
public Plan CurrentPlan { get; set; }
public bool ShouldCompare { get; set; }
public PlansCompareViewModel(Plan plan)
{
ShouldCompare = false;
PlanID = plan.PlanId;
CurrentPlan = plan;
}
public PlansCompareViewModel()
{
// TODO: Complete member initialization
}
public static IEnumerable<PlansCompareViewModel> CreatePlansVM(IEnumerable<Plan> plans)
{
return plans.Select(p => new PlansCompareViewModel(p)).AsEnumerable();
}
}
Controller:
public class PlansController : MyBaseController
{
[HttpPost]
public ActionResult ComparePlans(IEnumerable<PlanCompareViewModel> model)
{
//the model passed into here is NULL
}
}
And the problem is in the controller action. As far as I am aware, it should be posting an enumerable list of PlanCompareViewModels, yet it is null. When in inspect the post data being sent, it is sending the correct params. And if I were to change 'IEnumerable' to 'FormCollection', it contains the correct values. Can anyone see why the binder is not creating the correct object? I can get around this using javascript, but that defeats the purpose! Any help would be greatly appreciated!
解决方案
Your model is null because the way you're supplying the inputs to your form means the model binder has no way to distinguish between the elements. Right now, this code:
@foreach (var planVM in Model)
{
@Html.Partial("_partialView", planVM)
}
is not supplying any kind of index to those items. So it would repeatedly generate HTML output like this:
That index is what enables the model binder to associate the separate pieces of data, allowing it to construct the correct model. So here's what I'd suggest you do to fix it. Rather than looping over your collection, using a partial view, leverage the power of templates instead. Here's the steps you'd need to follow:
Create an EditorTemplates folder inside your view's current folder (e.g. if your view is HomeIndex.cshtml, create the folder HomeEditorTemplates).
Create a strongly-typed view in that directory with the name that matches your model. In your case that would be PlanCompareViewModel.cshtml.
Now, everything you have in your partial view wants to go in that template:
@model IEnumerable<PlanCompareViewModel>
@using (Html.BeginForm("ComparePlans", "Plans", FormMethod.Post, new { id = "compareForm" }))
{
<div>
@Html.EditorForModel()
</div>
}
DisplayTemplates and EditorTemplates are smart enough to know when they are handling collections. That means they will automatically generate the correct names, including indices, for your form elements so that you can correctly model bind to a collection.
