c# - 标签助手未在 ASP.NET Core 2 中处理

Question

我添加了以下标签助手:

using System;
using System.Linq;
using Microsoft.AspNetCore.Mvc.ModelBinding;
using Microsoft.AspNetCore.Mvc.Rendering;
using Microsoft.AspNetCore.Mvc.TagHelpers;
using Microsoft.AspNetCore.Mvc.ViewFeatures;
using Microsoft.AspNetCore.Razor.TagHelpers;

namespace X.TagHelpers
{
    [HtmlTargetElement(Attributes = ValidationForAttributeName + "," + ValidationErrorClassName)]
    public class ValidationClassTagHelper : TagHelper
    {
        private const string ValidationForAttributeName = "k-validation-for";
        private const string ValidationErrorClassName = "k-error-class";

        [HtmlAttributeName(ValidationForAttributeName)]
        public ModelExpression For { get; set; }

        [HtmlAttributeName(ValidationErrorClassName)]
        public string ValidationErrorClass { get; set; }

        [HtmlAttributeNotBound]
        [ViewContext]
        public ViewContext ViewContext { get; set; }

        public override void Process(TagHelperContext context, TagHelperOutput output)
        {
            Console.WriteLine("\n\n------------!!!!!!---------\n\n");
            ModelStateEntry entry;
            ViewContext.ViewData.ModelState.TryGetValue(For.Name, out entry);
            if (entry == null || !entry.Errors.Any()) return;
            var tagBuilder = new TagBuilder(context.TagName);
            tagBuilder.AddCssClass(ValidationErrorClass);
            output.MergeAttributes(tagBuilder);
        }
    }
}

然后在 _ViewImports.cshtml 中添加了以下行:

@addTagHelper *, X.TagHelpers

文件编译正确，如果我引入语法错误，dotnet build 会警告我。

然后在我的一个页面中添加:

<div k-validation-for="OldPassword" k-error-class="has-danger"></div>

如果我加载页面，我在服务器端看不到控制台输出，k-validation-for 和 k-error-class 被转发到生成的页面原样(与将 has-danger 类添加到 class 属性相反)。

我做错了什么？

Answer 1

注册 Tag Helper 时，需要的是程序集，而不是 namespace - 在 docs 中解释.

...the second parameter "Microsoft.AspNetCore.Mvc.TagHelpers" specifies the assembly containing the Tag Helpers. Microsoft.AspNetCore.Mvc.TagHelpers is the assembly for the built-in ASP.NET Core Tag Helpers.

所以在你的情况下，你可以改变这个:

@addTagHelper *, X.TagHelpers

对此:

@addTagHelper *, X