Link tag helper not working in asp.net core 2.2

问题

My link tag helpers are no longer working properly after migrating to asp.net core 2.2.

 <a class="btn btn-outline-primary" asp-controller="MyController" asp-action="MyAction" asp-route-id="@Id">Link</a>

This works fine when I set the compatibility version to 2.1, but produces an empty href when set to compatibility version 2.2.

<a class="btn btn-outline-primary" href="">Link</a>

I followed the steps Migrate from ASP.NET Core 2.1 to 2.2

 .SetCompatibilityVersion(CompatibilityVersion.Version_2_1);  --> Works

 .SetCompatibilityVersion(CompatibilityVersion.Version_2_2);  --> Doesn't work

Project file:

<Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
    <TargetFramework>netcoreapp2.2</TargetFramework>
    <TypeScriptToolsVersion>2.8</TypeScriptToolsVersion>
    <LangVersion>7.2</LangVersion>
    <AspNetCoreHostingModel>InProcess</AspNetCoreHostingModel>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.App" />
    <PackageReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Design" Version="2.2.2" />
    <PackageReference Include="Microsoft.Windows.Compatibility" Version="2.0.1" />
    <PackageReference Include="Sendgrid" Version="9.10.0" />
    <PackageReference Include="Stripe.net" Version="22.8.1" />
    <PackageReference Include="UAParser" Version="3.1.36" />
  </ItemGroup>

  <ItemGroup>
    <Folder Include="Data\Migrations\" />
  </ItemGroup>

</Project>

回答1:

I am pretty new in this technology, and I had the same problem. After I added

@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers
@addTagHelper *, MyNameSpace

in ViewImports.cshtml, as mentioned here https://docs.microsoft.com/en-us/aspnet/core/mvc/views/tag-helpers/authoring?view=aspnetcore-2.2 everything was fine.

回答2:

I had the same issue today on a new AspNet Core 2.2 Project created using the built in MVC Template. The tags were not generated in the HTML.

changing the following

services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);

to

services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);

Works and the tags are now rendered in the HTML, I done some digging and it looks as though this has been raised as an issue in AspNetCore 2.2. They mention it has been fixed in AspNetCore 3.0.0-preview3.

As mentioned here: https://github.com/aspnet/AspNetCore/issues/5055 and here https://github.com/aspnet/AspNetCore/issues/6471

If you need to use AspNetCore 2.2 then a temporary workaround, if viable is to ammend the following in your Startup.cs as mentioned on the issue raised.

services.AddMvc(options => options.EnableEndpointRouting = false)

来源：https://stackoverflow.com/questions/54722462/link-tag-helper-not-working-in-asp-net-core-2-2