编辑和保存复杂对象

Question

假设你有以下对象：

public class Address
{
  public String Line1 { get; set; }
  public String Line2 { get; set; }
  public String City { get; set; }
  public String State { get; set; }
  public String ZipCode { get; set; }

  public Address()
  {
  }
}

public class Contact
{
  public String FirstName { get; set; }
  public String LastName { get; set; }
  public String Telephone { get; set; }

  public Address BillingAddress { get; set; }
  public List<Address> ShippingAddresses { get; set; }

  public Contact()
  {
    // Assume anything that _could_ be null wouldn't be. I'm excluding
    // most "typical" error checking just to keep the examples simple
    this.BillingAddress = new Address();
    this.ShippingAddresses = new List<Address>();
  }
}

假设属性被[Required]、[Display] 和其他属性修饰。

然后是我的控制器（为了演示而简化）：

public ActionResult Edit(String id)
{
  Contact contact = ContactManager.FindByID(id);
  return View(model: contact);
}

[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Edit(Contact contact)
{
  if (ModelState.IsValid) //always fails
  {
    ContactManager.Save(contact);
    return RedirectToAction("Saved");
  }
  return View(model: contact);
}

我经常看到在 MVC 中编辑这样的对象的演示，但他们不断地将对象的集合分解为自己的形式（例如，编辑联系人，然后编辑联系人的特定地址）。另一方面，我试图在同一页面内编辑所有这些信息，但没有成功。例如：

@model Contact

// simplified for brevity
@using (Html.BeginForm())
{
  @Html.LabelFor(x => x.FirstName): @Html.EditorFor(x => x.FirstName)
  @Html.LabelFor(x => x.LastName): @Html.EditorFor(x => x.LastName)
  @Html.LabelFor(x => x.Telephone): @Html.EditorFor(x => x.Telephone)

  <div>
    @Html.LabelFor(x => x.BillingAddress.Line1): @Html.EditorFor(x => x.BillingAddress.Line1)
    @Html.LabelFor(x => x.BillingAddress.Line2): @Html.EditorFor(x => x.BillingAddress.Line2)
    @Html.LabelFor(x => x.BillingAddress.City): @Html.EditorFor(x => x.BillingAddress.City)
    @Html.LabelFor(x => x.BillingAddress.State): @Html.EditorFor(x => x.BillingAddress.State)
    @Html.LabelFor(x => x.BillingAddress.ZipCode): @Html.EditorFor(x => x.BillingAddress.ZipCode)
  </div>

  <div>
  @foreach (Address addr in Model.ShippingAddresses)
  {
    <div>
      @Html.LabelFor(x => addr.Line1): @Html.EditorFor(x => addr.Line1)
      @Html.LabelFor(x => addr.Line2): @Html.EditorFor(x => addr.Line2)
      @Html.LabelFor(x => addr.City): @Html.EditorFor(x => addr.City)
      @Html.LabelFor(x => addr.State): @Html.EditorFor(x => addr.State)
      @Html.LabelFor(x => addr.ZipCode): @Html.EditorFor(x => addr.ZipCode)
    </div>
  }
  </div>
}

我一直遇到的问题是，当我去保存信息时，ModelState.IsValid 永远不会通过。这样做有诀窍，还是只是在 MVC 领域之外？我想获取一个像Contact 这样的对象并将所有信息转储在一页上进行编辑，然后成功地重新保存它，但我似乎无法让它工作。 （我的下一步是绑定 ajax，以便您可以在该页面上动态添加/删除“ShipingAddresses”，但我需要先保存才能工作--K.I.S.S）

问题：

• ModelState.IsValid 几乎总是假的
• 集合项的表单元素通常具有相同的名称，因此在此演示中，ShippingAddresses 集合中的每个Line1 都以name="addr_Line1" 的形式转储到页面，而不是像我期望的那样ShippingAddresses[0]_Line1。

Answer 1

我猜ModelState.IsValid 是错误的，因为您没有正确填写收货地址集合。发生这种情况是因为您没有为输入字段使用正确的名称。查看following article 以更好地了解模型绑定器希望您的输入字段以什么格式命名，以便能够重新构造值。

您的代码没有生成正确的输入名称的原因是您使用了这个 foreach 循环，其中视图丢失了导航上下文的跟踪。

所以试试这样：

@for (var i = 0; i < Model.ShippingAddresses.Count; i++)
{
    <div>
        @Html.LabelFor(x => x.ShippingAddresses[i].Line1): 
        @Html.EditorFor(x => x.ShippingAddresses[i].Line1)

        @Html.LabelFor(x => x.ShippingAddresses[i].Line2): 
        @Html.EditorFor(x => x.ShippingAddresses[i].Line2)

        @Html.LabelFor(x => x.ShippingAddresses[i].City): 
        @Html.EditorFor(x => x.ShippingAddresses[i].City)

        @Html.LabelFor(x => x.ShippingAddresses[i].State): 
        @Html.EditorFor(x => x.ShippingAddresses[i].State)

        @Html.LabelFor(x => x.ShippingAddresses[i].ZipCode): 
        @Html.EditorFor(x => x.ShippingAddresses[i].ZipCode)
    </div>    
}

备注：请注意，我还使用 EditorFor 调用替换了您的重复标签，以有效地为这些字段生成输入字段。

甚至更好地使用这样的编辑器模板：

@model Contact

@using (Html.BeginForm())
{
    @Html.LabelFor(x => x.FirstName): 
    @Html.EditorFor(x => x.FirstName)

    @Html.LabelFor(x => x.LastName): 
    @Html.EditorFor(x => x.LastName)

    @Html.LabelFor(x => x.Telephone): 
    @Html.EditorFor(x => x.Telephone)

    @Html.EditorFor(x => x.BillingAddress)

    @Html.EditorFor(x => x.ShippingAddresses)
}

然后定义一个自定义编辑器模板，该模板将自动为ShippingAddresses 集合 (~/Views/Shared/EditorTemplates/Address.cshtml) 的每个元素呈现：

@model Address
<div>
    @Html.LabelFor(x => x.Line1): 
    @Html.EditorFor(x => x.Line1)

    @Html.LabelFor(x => x.Line2): 
    @Html.EditorFor(x => x.Line2)

    @Html.LabelFor(x => x.City): 
    @Html.EditorFor(x => x.City)

    @Html.LabelFor(x => x.State): 
    @Html.EditorFor(x => x.State)

    @Html.LabelFor(x => x.ZipCode): 
    @Html.EditorFor(x => x.ZipCode)
</div>

现在您不必再担心输入错误的名称了。不仅如此，您还为您的帐单地址和送货地址的集合重复使用地址编辑器模板。它使您的观点更加干燥。