如何将Bootstrap下拉样式应用于ASP.NET MVC DropDownList? [英] How to apply Bootstrap dropdown style to an ASP.NET MVC DropDownList?

问题描述

给出以下MVC剃刀代码，该代码从列表中创建一个下拉列表:

Given is the following MVC razor code which creates a dropdown from a list:

@Html.DropDownList("MyTestList", null, new { @class = "btn btn-default dropdown-toggle" })

这将创建以下下拉列表:

This will create the following dropdown:

使用getbootstrap.com中的代码时:

When using the code from getbootstrap.com:

<div class="dropdown">
    <button class="btn btn-default dropdown-toggle" type="button" id="dropdownMenu1" data-toggle="dropdown">
        Dropdown
        <span class="caret"></span>
    </button>
    <ul class="dropdown-menu" role="menu" aria-labelledby="dropdownMenu1">
        <li role="presentation"><a role="menuitem" tabindex="-1" href="#">test1</a></li>
        <li role="presentation"><a role="menuitem" tabindex="-1" href="#">test2</a></li>
    </ul>
</div>

它将显示如下所示的下拉列表:

It will show the dropdown like this:

问题: 使用@Html.DropDownList时是否可以与使用MVC中的HTML代码时获得相同的外观?

Question: Is it possible to get the same look and feel when using @Html.DropDownList as when using the HTML code from MVC?

推荐答案

无法使用Razor的@Html.DropDownList()方法创建您提到的Bootstrap下拉列表.尽管创建您自己的HTML帮助器很容易，该HTML帮助器将呈现创建上述下拉菜单所需的代码.

It's not possible to use Razor's @Html.DropDownList() method to create the Bootstrap dropdown you've mentioned. Though it'ss easy enough to create your own HTML helper that renders the code necessary to create the aforementioned dropdown.

有很多教程和指南(这样的)，它将引导您完成创建自定义HTML帮助程序的过程.创建它们实际上并不那么困难，并且确实可以帮助您加快开发时间并鼓励代码重用.

There are plenty of tutorials and guides (such as this one) that will take you through the process of creating a custom HTML Helper. They're really not that difficult to create and can really help speed up your development times and encourage code reuse.

更新:

鉴于此问题引起了人们的广泛关注，下面是(错误)答案得到了越来越多的赞成，这里是一个逾期很长(一年半！)的代码示例，其中有一个图像来演示这些差异.

Given the amount of attention this question is getting an the number of upvotes the (incorrect) answer below is getting, here is a long overdue (year and a half!) code sample with an image to demonstrate the differences.

您可以将此代码复制并粘贴到您的解决方案中，它应该可以工作.

You can copy and paste this code into your solution and it should work.

代码:

public class BootstrapHtml
{
    public static MvcHtmlString Dropdown(string id, List<SelectListItem> selectListItems, string label)
    {
        var button = new TagBuilder("button")
        {
            Attributes =
            {
                {"id", id},
                {"type", "button"},
                {"data-toggle", "dropdown"}
            }
        };

        button.AddCssClass("btn");
        button.AddCssClass("btn-default");
        button.AddCssClass("dropdown-toggle");

        button.SetInnerText(label);
        button.InnerHtml += " " + BuildCaret();

        var wrapper = new TagBuilder("div");
        wrapper.AddCssClass("dropdown");

        wrapper.InnerHtml += button;
        wrapper.InnerHtml += BuildDropdown(id, selectListItems);

        return new MvcHtmlString(wrapper.ToString());
    }

    private static string BuildCaret()
    {
        var caret = new TagBuilder("span");
        caret.AddCssClass("caret");

        return caret.ToString();
    }

    private static string BuildDropdown(string id, IEnumerable<SelectListItem> items)
    {
        var list = new TagBuilder("ul")
        {
            Attributes =
            {
                {"class", "dropdown-menu"},
                {"role", "menu"},
                {"aria-labelledby", id}
            }
        };

        var listItem = new TagBuilder("li");
        listItem.Attributes.Add("role", "presentation");

        items.ForEach(x => list.InnerHtml += "<li role=\"presentation\">" + BuildListRow(x) + "</li>");

        return list.ToString();
    }

    private static string BuildListRow(SelectListItem item)
    {
        var anchor = new TagBuilder("a")
        {
            Attributes =
            {
                {"role", "menuitem"},
                {"tabindex", "-1"},
                {"href", item.Value}
            }
        };

        anchor.SetInnerText(item.Text);

        return anchor.ToString();
    }
}

用法:

@using (Html.BeginForm("", "", FormMethod.Post))
{

    var items = new List<SelectListItem>()
    {
        new SelectListItem() { Text = "Item 1", Value = "#" },
        new SelectListItem() { Text = "Item 2", Value = "#" },
    };

    <div class="form-group">
        @Html.Label("Before", new { @class = "col-md-2 control-label" })
        <div class="col-md-10">
            @Html.DropDownList("Name", items, "Dropdown", new { @class = "form-control"})
        </div>
    </div>

    <br/>
    <br/>
    <br/>

    <div class="form-group">
        @Html.Label("After", new { @class = "col-md-2 control-label" })
        <div class="col-md-10">
            @BootstrapHtml.Dropdown("dropdownMenu1", items, "Dropdown")
        </div>
    </div>

}

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