如何使基于列表的编辑器模板正确绑定POST操作？

Question

我有一个模型,ApplicantBranchList在大型模型中用作属性,如下所示:

[Display(Name = "Where would you want to work?")]
public ApplicantBranchList PreferedBranches { get; set; }

ApplicantBranchList:

public class ApplicantBranchList : ViewModel
{
    public ApplicantBranchItem HeaderItem { get; set; }
    public ApplicantBranchList()
    {
        HeaderItem = new ApplicantBranchItem();
    }
    public void MapFromEntityList(IEnumerable<ApplicantBranch> applicantBranches)
    {
        var service = new BranchService(DbContext);
        var selectedIds = applicantBranches.Select(b => b.BranchId);
        Items = service.ReadBranches()
                       .Where(i => !i.IsDeleted)
                       .Select(p => new ApplicantBranchItem { BranchName = p.Name, WillWorkAt = selectedIds.Contains(p.Id) });
    }
    public IEnumerable<ApplicantBranchItem> Items { get; set; }
}

ApplicantBranchList有自己的编辑器模板,以及每个项目的内部编辑器模板ApplicantBranchList:

查看/共享/ EditorTemplates/ApplicantBranchList.cshtml:

@model Comair.RI.UI.Models.ApplicantBranchList
<table>
    <tr>
        <th style="display: none;"></th>
        <th>
            @Html.DisplayNameFor(model => model.HeaderItem.BranchName)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.HeaderItem.WillWorkAt)
        </th>
    </tr>
    @foreach (var item in Model.Items)
    {
        @Html.EditorFor(m => item)
    }
</table>

查看/共享/ EditorTemplates/ApplicantBranchItem.cshtml:

@model Comair.RI.UI.Models.ApplicantBranchItem
<tr>
    <td style="display: none;">
        @Html.HiddenFor(m => m.BranchId)
    </td>
    <td>
        @Html.DisplayFor(m => m.BranchName)
    </td>
    <td>
        @Html.EditorFor(m => m.WillWorkAt)
    </td>
</tr>

此编辑器在视图中正确呈现,但在后期操作中:

public ActionResult Create(ApplicantProfileModel model)
{
    if (ModelState.IsValid)
    {
        var branches = model.PreferedBranches;

PreferedBranches.Items是null.

我究竟做错了什么？

Answer 1

问题是ASP.NET无法弄清楚如何绑定到Model.Items属性.

要修复它替换:

public IEnumerable<ApplicantBranchItem> Items { get; set; }

有了这个:

public List<ApplicantBranchItem> Items { get; set; }

而不是:

@foreach (var item in Model.Items)
{
   @Html.EditorFor(m => item)
}

使用这个:

@for (var i = 0; i < Model.Items.Count; i++)
{
   @Html.EditorFor(model => model.Items[i]) // binding works only with items which are accessed by indexer
}

Answer 2

使用MVC和编辑器模板,您无需手动浏览列表并调用@HTMLEditorFor.

这样做:

@Html.EditorFor(model => model.Items)

是相同的:

@for (var i = 0; i < Model.Items.Count; i++)
{
   @Html.EditorFor(model => model.Items[i]) // binding works only with items which are accessed by indexer
}

MVC将处理项目的迭代,并为每个项目生成一次编辑器模板.如评论中所述,您的模板必须与您的模型命名相同.此外,您的模型定义应该是模型的单一表示,而不是IEnumerable类型.最后,如评论中所述,如果在调用@ Html.EditorFor()时指定模板名称参数,则不会对集合进行自动迭代.您将需要手动迭代,如上所示.