如何在 MVC 4 中使用 jQuery 更新 List<Model>

Question

我目前正在尝试使用修改后的索引视图创建设置页面。目标是让用户显示所有设置，并且可以在一个视图中更改所有设置并使用一个按钮保存所有设置。应使用 Ajax 更新设置。

我目前的做法：

查看：

<script language="javascript">
    $(function() {
        $('#editSettings').submit(function () {
            if ($(this).valid()) {
                $.ajax({
                    url: this.action,
                    type: this.method,
                    data: $(this).serialize(),
                    success: function (result)
                    {
                        alert(result);                       
                    }
                });
            }
            return false;
        });
    });
</script>

[ ... ]

@using (Ajax.BeginForm("Edit", "Settings", new AjaxOptions {UpdateTargetId = "result"}, new { @class = "form-horizontal", @id = "editSettings" } ))
{
    foreach (Setting item in ViewBag.Settings) 
    {
        @Html.Partial("_SingleSetting", item)
    }
    <input type="submit" value="modify" />
}

部分视图加载设置：

        <div class="control-group">
            <label class="control-label">@settingName</label>
            <div class="controls">
                @Html.EditorFor(model => model.Value)
                <span class="help-inline">@settingDescription</span>
            </div>
        </div>

型号：

[Table("Settings")]
public class Setting
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int SettingId { get; set; }

    public string Name { get; set; }

    [Required(AllowEmptyStrings = true)]
    [DisplayFormat(ConvertEmptyStringToNull = false)]
    public string Value { get; set; }
}

我正在使用 ViewBag.Settings = _db.Settings.ToList(); 设置 ViewBag

jQuery 将 Data 解析为以下方法：

    [HttpPost]
    public ActionResult Edit(IList<Setting> setting)
    {
        Console.WriteLine(setting.Count);
        return Content(""); // Currently for testing purposes only. Breakpoint is set to setting.Count
    }

Count 抛出错误，因为设置为 null。我很不确定如何解决这个问题。

谁能给我一个提示？

This 关于 SO 的主题已经涵盖了在没有 Ajax 的情况下更新集合。但我不会明白这一点。

感谢您的帮助。

Answer 1

您正在使用Ajax.BeginForm 并再次使用 jQuery 对表单进行 ajaxifying。那没有必要。但是您的代码的真正问题是部分输入字段的名称。您不尊重默认模型绑定器用于绑定到列表的naming convention。

让我们举一个完整的例子（为简单起见，去除了实体框架等所有噪音）：

型号：

public class Setting
{
    public int SettingId { get; set; }
    public string Name { get; set; }
    public string Value { get; set; }
}

控制器：

public class SettingsController : Controller
{
    public ActionResult Index()
    {
        // No idea why you are using ViewBag instead of view model
        // but I am really sick of repeating this so will leave it just that way
        ViewBag.Settings = Enumerable.Range(1, 5).Select(x => new Setting
        {
            SettingId = x,
            Name = "setting " + x,
            Value = "value " + x
        }).ToList();
        return View();
    }

    [HttpPost]
    public ActionResult Edit(IList<Setting> setting)
    {
        // Currently for testing purposes only. Breakpoint is set to setting.Count
        return Content(setting.Count.ToString()); 
    }
}

查看（~/Views/Settings/Index.cshtml）：

@using (Html.BeginForm("Edit", "Settings", FormMethod.Post, new { @class = "form-horizontal", id = "editSettings" }))
{
    foreach (Setting item in ViewBag.Settings) 
    {
        @Html.Partial("_SingleSetting", item)
    }
    <input type="submit" value="modify" />
}

@section scripts {
    <script type="text/javascript">
        $('#editSettings').submit(function () {
            if ($(this).valid()) {
                $.ajax({
                    url: this.action,
                    type: this.method,
                    data: $(this).serialize(),
                    success: function (result) {
                        alert(result);
                    }
                });
            }
            return false;
        });
    </script>
}

部分设置 (~/Views/Settings/_SingleSetting.cshtml)：

@model Setting
@{
    var index = Guid.NewGuid().ToString();
    ViewData.TemplateInfo.HtmlFieldPrefix = "[" + index + "]";
}

<input type="hidden" name="index" value="@index" />

<div class="control-group">
    <label class="control-label">@Html.LabelFor(x => x.Name)</label>
    <div class="controls">
        @Html.EditorFor(model => model.Value)
    </div>
</div>

注意在部分内部，有必要更改 HtmlFieldPrefix 以便 html 帮助程序为您的输入字段生成正确的名称并遵守命名约定。

---

好的，现在让我们删除 ViewCrap 并正确地做事（即当然是使用视图模型）。

和往常一样，我们从编写视图模型开始：

public class MyViewModel
{
    public IList<Setting> Settings { get; set; }
}

然后我们适配控制器：

public class SettingsController : Controller
{
    public ActionResult Index()
    {
        var model = new MyViewModel();

        // you will probably wanna call your database here to 
        // retrieve those values, but for the purpose of my example that
        // should be fine
        model.Settings = Enumerable.Range(1, 5).Select(x => new Setting
        {
            SettingId = x,
            Name = "setting " + x,
            Value = "value " + x
        }).ToList();
        return View(model);
    }

    [HttpPost]
    public ActionResult Edit(IList<Setting> setting)
    {
        // Currently for testing purposes only. Breakpoint is set to setting.Count
        return Content(setting.Count.ToString()); 
    }
}

查看（~/Views/Settings/Index.cshtml）：

@model MyViewModel

@using (Html.BeginForm("Edit", "Settings", FormMethod.Post, new { @class = "form-horizontal", id = "editSettings" }))
{
    @Html.EditorFor(x => x.Settings)
    <input type="submit" value="modify" />
}

@section scripts {
    <script type="text/javascript">
        $('#editSettings').submit(function () {
            if ($(this).valid()) {
                $.ajax({
                    url: this.action,
                    type: this.method,
                    data: $(this).serialize(),
                    success: function (result) {
                        alert(result);
                    }
                });
            }
            return false;
        });
    </script>
}

设置模型的编辑器模板 (~/Views/Settings/EditorTemplates/Settings.cshtml)：

@model Setting
<div class="control-group">
    <label class="control-label">@Html.LabelFor(x => x.Name)</label>
    <div class="controls">
        @Html.EditorFor(model => model.Value)
    </div>
</div>

现在所有的作品都按照惯例。无需编写任何 foreach 循环。索引视图中的@Html.EditorFor(x => x.Settings) 调用分析视图模型的设置属性并检测到它是某个其他模型的集合（在本例中为Setting）。因此它将开始循环遍历该集合并搜索相应的编辑器模板 (~/Views/Settings/EditorTemplates/Setting.cshtml)，该模板将自动为该集合的每个元素呈现。因此，您甚至不需要在视图中编写任何循环。除了简化代码之外，现在编辑器模板中的Html.EditorFor(x => x.Value) 将为输入字段生成正确的名称。