如何在 MVC4 中编辑相关对象的属性？

Question

我在编辑相关对象的属性时遇到了一些问题。代码如下：

型号：

DocumentLine.cs

/// <summary>
/// States the base implementation for all document lines in a purchasing module.
/// </summary>
public class DocumentLine : Keyed
{
    // ... some other properties

    /// <summary>
    /// Gets or sets the current line's document header.
    /// </summary>
    [Navigation]
    [Display(ResourceType = typeof(Resources.ApplicationResources), Name = "Header")]
    public virtual DocumentHeader Header { get; set; }
}

DocumentHeader.cs

/// <summary>
/// States the base implementation for all document headers in a purchasing module.
/// </summary>
public class DocumentHeader : Keyed
{
    /// <summary>
    /// Gets or sets the current header's document number.
    /// </summary>
    [Required]
    [Display(ResourceType = typeof(Resources.ApplicationResources), Name = "DocumentNumber")]
    public string DocumentNumber { get; set; }

    /// <summary>
    /// Gets or sets the extra cost of the document.
    /// </summary>
    [Display(ResourceType = typeof(Resources.ApplicationResources), Name = "ExtraCost")]
    [RegularExpression(@"^\d*$", ErrorMessageResourceType=typeof(Resources.ApplicationResources), ErrorMessageResourceName= "Exception_ExtraCost_Error")]
    public decimal ExtraCost { get; set; }

    /// <summary>
    /// Gets or sets the vat's extra cost of the document.
    /// </summary>
    [Display(ResourceType = typeof(Resources.ApplicationResources), Name = "ExtraVat")]
    [RegularExpression(@"^\d*$", ErrorMessageResourceType = typeof(Resources.ApplicationResources), ErrorMessageResourceName = "Exception_ExtraVat_Error")]
    public decimal ExtraVat { get; set; }

    /// <summary>
    /// Gets or sets the navigation property to all dependant Document lines.
    /// </summary>
    [Required]
    [Navigation]
    [Display(ResourceType = typeof(Resources.ApplicationResources), Name = "DocumentLines")]
    public virtual ICollection<DocumentLine> DocumentLines { get; set; }
}

查看：

@Html.HiddenFor(model => model.Header.Id, Model.Header != null ? Model.Header.Id : null)
<div class="display-label">
    @Html.DisplayNameFor(model => model.Header.ExtraCost)
</div>
<div class="display-field">
    <input type="text" name="Header.ExtraCost" id="Header.ExtraCost" data-varname="header.extraCost" value="@(Model.Header.ExtraCost)" />
    @Html.ValidationMessageFor(model => model.Header.ExtraCost)
</div>
<div class="display-label">
    @Html.DisplayNameFor(model => model.Header.ExtraVat)
</div>
<div class="display-field">
    <input type="text" name="Header.ExtraVat" id="Header.ExtraVat" data-varname="header.extraVat" value="@(Model.Header.ExtraVat)" />
    @Html.ValidationMessageFor(model => model.Header.ExtraVat)
</div>

我知道 MVC 会跟踪输入的 id 和名称以将值传递给控制器​​，这就是为什么我将隐藏输入设置为 Header.Id 值。此视图正确显示了值，所以我认为问题不在这里。

控制器：

我有一个通用的控制器方法可以编辑，它工作正常，尽管我可能必须针对这种特殊情况重写它。

/// <summary>
/// Handles the POST event for the Edit action, updating an existing TEntity object.
/// </summary>
/// <param name="id">Id of the TEntity object to update.</param>
/// <param name="model">TEntity object with properties updated.</param>
/// <returns>Redirection to the Index action if succeeded, the Edit View otherwise.</returns>
[HttpPost]
public virtual ActionResult Edit(string id, TEntity model)
{
    var request = new RestSharp.RestRequest(Resource + "?id={id}", RestSharp.Method.PUT) { RequestFormat = RestSharp.DataFormat.Json }
        .AddParameter("id", id, RestSharp.ParameterType.UrlSegment)
        .AddBody(model);
    var response = Client.Execute(request);

    // Handle response errors
    HandleResponseErrors(response);

    if (Errors.Length == 0)
        return RedirectToAction("Index");
    else
    {
        ViewBag.Errors = Errors;
        return View(model);
    }
}

主要问题是这段代码不仅没有编辑相关的对象值，而且还将DocumentLine的Header.Id值设置为null。

有什么建议吗？

Answer 1

问题很可能出现在我的回答的最后一段中，但这里有一些其他提示可以帮助您调试此类问题..

查看 Google chrome 中的网络选项卡，或下载 Firebug for Firefox 并查看您实际发布到该方法的内容，在该方法上放置一个断点并确保该方法的参数实际上正在获取值。

删除“标题”。根据您输入的名称和 ID，实际使用 @Html.EditorFor(model => model.ExtraCost) 反而。您还没有为 Edit 视图发布 GET 方法，在此设置断点并确保将实体传递给视图。

如果你得到这个工作，你只需要使用@Html.HiddenFor(model => model.Id)

在您看来，Id 将作为 Id 发布，放入您的控制器中称为 id，thsi 不会绑定，所以我怀疑 Id 永远不会真正传递到 ActionResult。

Answer 2

我不得不修改默认的 RestSharp PUT 方法以强制它首先更新文档标题，然后更新发票行。

/// PUT api/<controller>/5
/// <summary>
/// Upserts a InvoiceLine object and its DocumentHeader to the underlying DataContext
/// </summary>
/// <param name="id">Id of the InvoiceLine object.</param>
/// <param name="value">The InvoiceLine object to upsert.</param>
/// <returns>An HttpResponseMessage with HttpStatusCode.Ok if everything worked correctly. An exception otherwise.</returns>
public override HttpResponseMessage Put(string id, [FromBody]InvoiceLine value)
{
    //If creation date is in UTC format we must change it to local time
    value.DateCreated = value.DateCreated.ToLocalTime();

    //update the document header if there is any change
    var header = Database.Set<DocumentHeader>()
        .FirstOrDefault(x => x.Id == value.Header.Id);

    if (header != null)
    {
        value.Header.DocumentLines = header.DocumentLines;
        value.Header.DocumentNumber = header.DocumentNumber;
        Database.Entry<DocumentHeader>(header)
            .CurrentValues.SetValues(value.Header);
    }
    else
    {
        Database.Set<DocumentHeader>().Add(value.Header);
    }

    // If entity exists, set current values to atomic properties
    // Otherwise, insert as new
    var entity = Database.Set<InvoiceLine>()
        .FirstOrDefault(x => x.Id == id);

    if (entity != null)
    {
        Database.Entry<InvoiceLine>(entity)
            .CurrentValues.SetValues(value);
        FixNavigationProperties(ref entity, value);
    }
    else
    {
        FixNavigationProperties(ref value);
        Database.Set<InvoiceLine>().Add(value);
    }

    if (value is ISynchronizable)
        (value as ISynchronizable).LastUpdated = DateTime.UtcNow;

    // Save changes and handle errors
    SaveChanges();

    return new HttpResponseMessage(HttpStatusCode.OK);
}

这对我有用。希望对您有所帮助。