编辑和保存复杂对象

Question

假设您有以下对象：

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>();
  }
}

假设属性用 [Required]、[Display] 和其他属性装饰。

然后是我的控制器（简化的为了演示）：

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);
}

我不断看到在 MVC 中编辑这样的对象的演示，但它们不断地将对象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。是否有这样做的技巧，或者它是否超出了 MVC 的范围？我想采用像 Contact 这样的对象并将所有信息转储到一页上进行编辑，并成功重新保存，但我似乎无法让它工作。 （我的下一步是结合 ajax，以便您可以动态添加/删除该页面上的“ShipingAddresses”，但我需要先保存才能工作 - KISS）

问题：

• ModelState.IsValid 几乎总是false
• 集合项的表单元素经常具有相同的名称，因此在此演示中，ShippingAddresses 集合中的每个 Line1 都会转储到页面，如下所示name="addr_Line1" 而不是像我期望的那样 ShippingAddresses[0]_Line1 。

Answer 1

我猜 ModelState.IsValid 是 false，因为您没有正确填充送货地址集合。发生这种情况是因为您没有为输入字段使用正确的名称。请参阅以下文章，以更好地了解模型绑定程序期望您的输入采用什么格式要命名的字段以便能够重建值。

您的代码未生成正确的输入名称的原因是因为您使用了此 foreach 循环，其中视图丢失了导航上下文的跟踪。

因此，请像这样尝试：

@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 调用替换了重复的标签，以有效地为这些字段生成输入字段。

或者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 集合的每个元素呈现 (~/Views/Shared/EditorTemplates/Address.cshtml)：

@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名称错误了。不仅如此，您还为您的帐单地址和送货地址集合重复使用地址编辑器模板。它让你的观点更加干燥。