c# - TagHelperOutput 将属性添加到结束，而不是开始

Question

我注意到 TagHelperOutput Attribute.Add，将文本添加到每个属性的开头。如何让它为每个属性添加到末尾。

base.Process(context, output);
output.Attributes.Add("class","test");

所以目前如果现有类是“按钮”，新类将是“测试按钮”。我希望它是 html 树中所有类的“按钮测试”

这个问题是针对 TagBuilder 的，

TagBuilder AddCssClass 顺序，添加到开头，末尾如何添加新类？

标签： c#html.netasp.net-core.net-core

Answer 1

您可以CreateOrMergeAttribute在标签助手中自定义一个方法，并首先将新的 css 类添加到属性列表中。如下所示：

    public class EmailTagHelper: TagHelper
{
    private const string EmailDomain = "contoso.com";

    // Can be passed via <email mail-to="..." />. 
    // PascalCase gets translated into kebab-case.
    public string MailTo { get; set; }

    public override void Process(TagHelperContext context, TagHelperOutput output)
    {
        output.TagName = "a";    // Replaces <email> with <a> tag

        var address = MailTo + "@" + EmailDomain;

        output.Attributes.SetAttribute("href", "mailto:" + address);
        output.Content.SetContent(address);

        CreateOrMergeAttribute("class", "test", output);
    }

    private void CreateOrMergeAttribute(string name, object content, TagHelperOutput output)
    {
        var currentAttribute = output.Attributes.FirstOrDefault(attribute => attribute.Name == name);
        if (currentAttribute == null)
        {
            var attribute = new TagHelperAttribute(name, content);
            output.Attributes.Add(attribute);
        }
        else
        {
            var newAttribute = new TagHelperAttribute(
                name,
                $"{currentAttribute.Value.ToString()} {content.ToString()}",
                currentAttribute.ValueStyle);
            output.Attributes.Remove(currentAttribute);
            output.Attributes.Add(newAttribute);
        }
    }
}

结果截图：