标签助手未在 ASP.NET Core 2 中处理 [英] Tag helper not being processed in ASP.NET Core 2

问题描述

我添加了以下标签助手:

I've added the following tag helper:

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("

------------!!!!!!---------

");
            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:

and then in _ViewImports.cshtml I've added the line:

@addTagHelper *, X.TagHelpers

文件已正确编译，如果我引入语法错误dotnet build 会警告我.

The file is compiled correctly and if I introduce a syntax error dotnet build warns me about it.

然后在我的其中一个页面中添加:

Then in one of my pages I add:

<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).

If I load the page I see no console output on the server side and the k-validation-for and k-error-class are forwarded to the generated page as is (as opposed to adding the has-danger class to the class attribute).

我做错了什么?

推荐答案

在注册标签助手时，需要的是程序集，而不是命名空间——在 docs.

When registering Tag Helpers, it’s the assembly that is required, not the namespace - explained in the docs.

...第二个参数Microsoft.AspNetCore.Mvc.TagHelpers"指定包含标记帮助程序的程序集.Microsoft.AspNetCore.Mvc.TagHelpers 是内置 ASP.NET Core Tag Helpers 的程序集.

...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:

So in your case, you can just change this:

@addTagHelper *, X.TagHelpers

为此:

@addTagHelper *, X

这篇关于标签助手未在 ASP.NET Core 2 中处理的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！