Asp MVC 4创建类似于Html.BeginForm的自定义html辅助方法

Question

我有以下html:

<div data-bind="stopBindings">

    <div data-viewId="languageList" data-bind="with: viewModel">
       <table>
              <tr>
                   <td ><label for="availableLanguages">Available Languages:</label></td>
              </tr>
       <table>
    </div>

</div>

我想制作一个自定义的html助手并像这样使用它(类似于Html.BeginForm)

@Html.BeginView()
{
    <table>
        <tr>
            <td ><label for="availableLanguages">Available Languages:</label></td>
        </tr>
    </table>
}

我开始制作我的助手方法

public static class BeginViewHelper
    {
        public static MvcHtmlString BeginView(this HtmlHelper helper, string viewId)
        {

            var parentDiv = new TagBuilder("div");
            parentDiv.MergeAttribute("data-bind", "preventBinding: true");
            return new MvcHtmlString();
        }

    }

我读了如何制作基本的html助手,但我看到的例子并没有给我提供如何在我的情况下制作它的信息.我对asp mvc很新,每一个帮助都将不胜感激.

更新2:

显然我错过了一些东西.我在我的观点中称之为:

@Html.BeginView()
{
    <table>
        <tr>
            <td ><label >test</label></td>
        </tr>
    </table>
}

一切看起来都很好,甚至还有智能感知.但浏览器中的输出如下:

Omega.UI.WebMvc.Helpers.BeginViewHelper+MyView { 


test

 } 

这是我的助手方法:

namespace Omega.UI.WebMvc.Helpers
{
    public static class BeginViewHelper
    {
        public static IDisposable BeginView(this HtmlHelper helper)
        {
            helper.ViewContext.Writer.Write("<div data-bind=\"preventBinding: true\">");
            helper.ViewContext.Writer.Write("<div data-viewId=\"test\">");

            return new MyView(helper);
        }

        class MyView : IDisposable
        {
            private HtmlHelper _helper;

            public MyView(HtmlHelper helper)
            {
                this._helper = helper;
            }

            public void Dispose()
            {
                this._helper.ViewContext.Writer.Write("</div>");
                this._helper.ViewContext.Writer.Write("</div>");
            }
        }
    }
}

我在〜/ Views/web.config中注册了名称空间

 <add namespace="Omega.UI.WebMvc.Helpers" />

Answer 1

你不能返回MvcHtmlString.而不是你应该将html写入编写器并返回实现IDisposable的类,并且在调用Dispose期间将写入HTML的结束部分.

public static class BeginViewHelper
{
    public static IDisposable BeginView(this HtmlHelper helper, string viewId)
    {
        helper.ViewContext.Writer.Write(string.Format("<div id='{0}'>", viewId));

        return new MyView(helper);
    }

    class MyView : IDisposable
    {
        private HtmlHelper helper;

        public MyView(HtmlHelper helper)
        {
            this.helper = helper;
        }

        public void Dispose()
        {
            this.helper.ViewContext.Writer.Write("</div>");
        }
    }
}

如果您有更复杂的结构,可以尝试使用TagBuilder:

TagBuilder tb = new TagBuilder("div");
helper.ViewContext.Writer.Write(tb.ToString(TagRenderMode.StartTag));

Answer 2

Slawek有正确的答案,但我想我会用我的经验补充它.

我想创建一个帮助器来在页面上显示小部件(几乎就像带有标题栏和内容部分的jQuery小部件).有效的东西:

@using (Html.BeginWidget("Widget Title", 3 /* columnWidth */))
{
    @* Widget Contents *@
}

MVC源使用类似于Slawek发布的内容,但我觉得将开始标记放在帮助器中并且实际对象中的结束标记不是"整洁",也没有在核心位置保留关注点.如果我想改变外观,我现在在两个地方这样做,而不是我认为是一个合乎逻辑的地方.所以我想出了以下内容:

/// <summary>
/// Widget container
/// </summary>
/// <remarks>
/// We make it IDIsposable so we can use it like Html.BeginForm and when the @using(){} block has ended,
/// the end of the widget's content is output.
/// </remarks>
public class HtmlWidget : IDisposable
{
    #region CTor

    // store some references for ease of use
    private readonly ViewContext viewContext;
    private readonly System.IO.TextWriter textWriter;

    /// <summary>
    /// Initialize the box by passing it the view context (so we can
    /// reference the stream writer) Then call the BeginWidget method
    /// to begin the output of the widget
    /// </summary>
    /// <param name="viewContext">Reference to the viewcontext</param>
    /// <param name="title">Title of the widget</param>
    /// <param name="columnWidth">Width of the widget (column layout)</param>
    public HtmlWidget(ViewContext viewContext, String title, Int32 columnWidth = 6)
    {
        if (viewContext == null)
            throw new ArgumentNullException("viewContext");
        if (String.IsNullOrWhiteSpace(title))
            throw new ArgumentNullException("title");
        if (columnWidth < 1 || columnWidth > 12)
            throw new ArgumentOutOfRangeException("columnWidth", "Value must be from 1-12");

        this.viewContext = viewContext;
        this.textWriter = this.viewContext.Writer;

        this.BeginWidget(title, columnWidth);
    }

    #endregion

    #region Widget rendering

    /// <summary>
    /// Outputs the opening HTML for the widget
    /// </summary>
    /// <param name="title">Title of the widget</param>
    /// <param name="columnWidth">Widget width (columns layout)</param>
    protected virtual void BeginWidget(String title, Int32 columnWidth)
    {
        title = HttpUtility.HtmlDecode(title);

        var html = new System.Text.StringBuilder();

        html.AppendFormat("<div class=\"box grid_{0}\">", columnWidth).AppendLine();
        html.AppendFormat("<div class=\"box-head\">{0}</div>", title).AppendLine();
        html.Append("<div class=\"box-content\">").AppendLine();

        this.textWriter.WriteLine(html.ToString());
    }

    /// <summary>
    /// Outputs the closing HTML for the widget
    /// </summary>
    protected virtual void EndWidget()
    {
        this.textWriter.WriteLine("</div></div>");
    }

    #endregion

    #region IDisposable

    private Boolean isDisposed;

    public void Dispose()
    {
        this.Dispose(true);
        GC.SuppressFinalize(this);
    }

    public virtual void Dispose(Boolean disposing)
    {
        if (!this.isDisposed)
        {
            this.isDisposed = true;
            this.EndWidget();
            this.textWriter.Flush();
        }
    }

    #endregion
}

然后,这使得我们的助手更加清晰(并且在两个地方没有UI代码):

public static HtmlWidget BeginWidget(this HtmlHelper htmlHelper, String title, Int32 columnWidth = 12)
{
  return new HtmlWidget(htmlHelper.ViewContext, title, columnWidth);
}

然后我们可以像在这篇文章的顶部那样使用它.