发表新帖
发表新帖

ASP.NET MVC razor: conditional attribute in HTML

后端 未结
关注
7 1659
鱼传尺愫
鱼传尺愫 2020-12-02 15:21

Code below doesn\'t seems clean. Any suggestion to improve the code?

  • class=\
    • 相关标签:
    7条回答
    • -上瘾入骨i
      2020-12-02 15:30 
      <li class="@(ViewBag.pagename == "Business details" ? "active" : null)">

      You should replace the inline style="..." with a separate classname and use the same syntax there.

      However, it would be cleaner to make a separate HTML helper extension method that takes a page and action name and generates the HTML generically.

      0 讨论(0)
    • 伪装坚强ぢ
      2020-12-02 15:30

      I use a small helper method that will conditionally add an attribute if the value is non-empty, and, if defined, when a Boolean function expression evaluates to true:

      public static MvcHtmlString Attr(this HtmlHelper helper, string name, string value, Func<bool> condition = null)
{
    if (string.IsNullOrEmpty(name) || string.IsNullOrEmpty(value))
    {
        return MvcHtmlString.Empty;
    }

    var render = condition != null ? condition() : true;

    return render ? 
        new MvcHtmlString(string.Format("{0}=\"{1}\"", name, HttpUtility.HtmlAttributeEncode(value))) : 
        MvcHtmlString.Empty;
}

      Once defined, I can use this method in my Razor views:

      <li @(Html.Attr("class", "new", () => example.isNew))>
...
</li>

      The above code will render <li class="new">...</li> if example.isNew == true, if not will omit the entire class attribute.

      0 讨论(0)
    • 余生分开走
      2020-12-02 15:31

      Based on defrosts answer here an adaptation, taking an object instead of a string:

          public static MvcHtmlString ConditionalAttr(this HtmlHelper helper, string attributeName, object value, Func<bool> condition)
    {
        if (string.IsNullOrEmpty(attributeName) || value == null)
        {
            return MvcHtmlString.Empty;
        }

        var render = condition != null ? condition() : true;

        return render ? 
            new MvcHtmlString($"{attributeName}=\"{HttpUtility.HtmlAttributeEncode(value.ToString())}\"") : 
            MvcHtmlString.Empty;
    }

      This way you don't have to turn your other datatypes in strings before passing them, saving a fiew .ToString(). There is a difference tho: passing an empty string will still render. As example:

      @Html.ConditionalAttr("data-foo", "", () => Model.IsFooNeeded)

// Ouput:
data-foo=""
      0 讨论(0)
    • 伪装坚强ぢ
      2020-12-02 15:34 
      @{ var classAttr= needClass ? "class=\"class-name\"" : "" }

      and then in the HTML

      <li @Html.Raw(classAttr) >
      0 讨论(0)
    • 遥遥无期
      2020-12-02 15:36

      MVC has conditional attributes built in...

      <div @{if (myClass != null) { <text>class="@myClass"</text> } }>Content</div>
<div class="@myClass">Content</div>

      If @myClass is null, it just won't use the attribute at all...

      I know that may not quite solve your current issue, but it is noteworthy!

      http://weblogs.asp.net/jgalloway/archive/2012/02/16/asp-net-4-beta-released.aspx

      0 讨论(0)
    • 时光取名叫无心
      2020-12-02 15:37

      In MVC4 

      <!DOCTYPE html>
<html>
<head>
</head>
<body>
    @{
        string css = "myDiv";
    }
    <div class='@css'></div>
</body>
</html>

      or

      <!DOCTYPE html>
<html>
<head>
</head>
<body>
    @{
        string css = "class=myDiv";
    }
    <div @css></div>
</body>
</html>

      More are here: http://evolpin.wordpress.com/2012/05/20/mvc-4-code-enhancements/

      0 讨论(0)
     看不清?
    提交回复
    热议问题