asp.net核心标签帮助程序,用于有条件地将类添加到元素 [英] asp.net core tag helper for conditionally add class to an element
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问题描述
在Asp.Net MVC中,我们可以按以下代码有条件地添加类:
In Asp.Net MVC we can add class conditionally as following code:
<div class="choice @(Model.Active?"active":"")">
</div>
如何通过使用tagHelper并删除其他有条件的部件来实现此目的.
How can do this by using tagHelper and by remove else part in condition.
推荐答案
可以通过遵循tagHelper提供的条件来添加条件CSS类. 像AnchorTagHelper asp-route- *这样的代码用于添加路由值.
Ability to add a conditional css class by following tagHelper provides. this code like AnchorTagHelper asp-route-* for add route values acts.
[HtmlTargetElement("div", Attributes = ClassPrefix + "*")]
public class ConditionClassTagHelper : TagHelper
{
private const string ClassPrefix = "condition-class-";
[HtmlAttributeName("class")]
public string CssClass { get; set; }
private IDictionary<string, bool> _classValues;
[HtmlAttributeName("", DictionaryAttributePrefix = ClassPrefix)]
public IDictionary<string, bool> ClassValues
{
get {
return _classValues ?? (_classValues =
new Dictionary<string, bool>(StringComparer.OrdinalIgnoreCase));
}
set{ _classValues = value; }
}
public override void Process(TagHelperContext context, TagHelperOutput output)
{
var items = _classValues.Where(e => e.Value).Select(e=>e.Key).ToList();
if (!string.IsNullOrEmpty(CssClass))
{
items.Insert(0, CssClass);
}
if (items.Any())
{
var classes = string.Join(" ", items.ToArray());
output.Attributes.Add("class", classes);
}
}
}
在_ViewImports.cshtml中添加对taghelper的引用,如下所示
in _ViewImports.cshtml add reference to taghelper as following
@addTagHelper "*, WebApplication3"
在视图中使用tagHelper:
Use tagHelper in View:
<div condition-class-active="Model.Active" condition-class-show="Model.Display">
</div>
Active = true和Display = true的结果是:
result for Active = true and Display = true is:
<div class="active show">
</div>
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