错误 CS0234：命名空间“System.Web”中不存在类型或命名空间名称“Mvc”

Question

我正在使用 VS Code 创建一个 asp.net 项目。这个问题首先被提出是因为我需要使用 AllowAnonymous 操作过滤器。它给出了“ The type or namespace name 'AllowAnonymousAttribute' could not be found.”的错误所以我添加了使用 System.Web.Mvc; 在开始部分。它显示error CS0234: The type or namespace name 'Mvc' does not exist in the namespace 'System.Web'你能给出任何建议吗？谢谢。using System;using System.Collections.Generic;using System.Linq;using System.Web.Mvc;using System.Threading.Tasks;using Microsoft.AspNetCore.Mvc;using DatingApp.API.Data;using Microsoft.EntityFrameworkCore;namespace DatingApp.API.Controllers{    [AllowAnonymous]    [Route("api/[controller]")]    public class ValuesController : Controller    {        private readonly DataContext _context;        public ValuesController(DataContext context)        {            _context = context;        }        // GET api/values        [HttpGet]        public async Task<IActionResult> GetValues()        {            var values=await _context.Values.ToListAsync();            return Ok(values);        }......运行后dotnet watch run，它给出了如下错误。watch : StartedControllers\ValuesController.cs(4,18): error CS0234: The type or namespace name 'Mvc' does not exist in the namespace 'System.Web' (are you missing an assembly reference?) [C:\Xumin\projects\DatingApp\DatingApp.API\DatingApp.API.csproj]Controllers\ValuesController.cs(12,6): error CS0246: The type or namespace name 'AllowAnonymousAttribute' could not be found (are you missing a using directive or an assembly reference?) [C:\Xumin\projects\DatingApp\DatingApp.API\DatingApp.API.csproj]Controllers\ValuesController.cs(12,6): error CS0246: The type or namespace name 'AllowAnonymous' could not be found (are you missing a using directive or an assembly reference?) [C:\Xumin\projects\DatingApp\DatingApp.API\DatingApp.API.csproj]