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

时间:2013-01-09 13:14:40

标签: c# asp.net-mvc-3 asp.net-mvc-4

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>

我想创建一个自定义的html帮助器并像这样使用它(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,但是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。我是asp mvc的新手,非常感谢每一位帮助。

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>
}

一切似乎都很好,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" />

3 个答案:

答案 0 :(得分:20)

您无法返回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));

答案 1 :(得分:8)

Slawekcorrect answer,但我想我会根据自己的经验添加它。

我想创建一个帮助程序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)。有什么影响:

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

MVC源代码使用与Slawek发布的内容类似的内容,但我觉得将开始标记放在帮助程序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。

答案 2 :(得分:3)

asp.net mvc的BeginForm方法返回IDisposable类的MvcForm实例。如果您查看asp.net mvc code on codeplex内部,可以查看asp.net mvc团队如何开发此功能。

看看这些链接:

MvcForm类(IDisposable) http://aspnetwebstack.codeplex.com/SourceControl/changeset/view/8b17c2c49f88#src/System.Web.Mvc/Html/MvcForm.cs

表单扩展(用于html帮助程序) http://aspnetwebstack.codeplex.com/SourceControl/changeset/view/8b17c2c49f88#src/System.Web.Mvc/Html/FormExtensions.cs