private class AsyncLoginImpl : IAsyncActionFilter {
       public async Task OnActionExecutionAsync(ActionExecutingContext context, ActionExecutionDelegate next) {
在这里使用context.Result是不是会出现上述情况?
    }
}

using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Filters;
using Microsoft.Extensions.Configuration;
using Newtonsoft.Json;
using Silver.Core;
using Silver.Core.Domain.Identity;
using System;
using System.Linq;
using System.Threading.Tasks;
using System.Web;
using Microsoft.Extensions.Logging;

namespace Silver.Web.Framework.Attributes {
    public class WeChatAttribute : TypeFilterAttribute {
        public WeChatAttribute() : base(typeof(AsyncLoginImpl)) {
        }

        private class AsyncLoginImpl : IAsyncActionFilter {
            public AsyncLoginImpl(UserManager<User> userManager, SignInManager<User> signInManager, IConfiguration cfg, IHttpHelper http, ILogger<AsyncLoginImpl> logger) {
                _userManager = userManager;
                _signInManager = signInManager;
                _cfg = cfg;
                _http = http;
                _logger = logger;
            }

            private readonly UserManager<User> _userManager;
            private readonly SignInManager<User> _signInManager;
            private readonly IConfiguration _cfg;
            private readonly IHttpHelper _http;
            private readonly ILogger<AsyncLoginImpl> _logger;
            public async Task OnActionExecutionAsync(ActionExecutingContext context, ActionExecutionDelegate next) {
                var httpContext = context.HttpContext;
                if (_signInManager.IsSignedIn(httpContext.User))
                    await next();
                else if (httpContext.Request.Headers["User-Agent"].ToString()
                             .IndexOf("MicroMessenger", StringComparison.OrdinalIgnoreCase) > 0) {
                    var query = httpContext.Request.Query;
                    var code = query.SingleOrDefault(c => c.Key == "code");
                    var appid = _cfg.GetValue<string>("Authentication:WeChat:AppID");
                    var appsecret = _cfg.GetValue<string>("Authentication:WeChat:AppSecret");if (string.IsNullOrEmpty(code.Value)) {
                        var redirect_uri = HttpUtility.UrlEncode(_cfg.GetValue<string>("Url"));
                        var url =
                            $"https://open.weixin.qq.com/connect/oauth2/authorize?appid={appid}&redirect_uri={redirect_uri}&response_type=code&scope=snsapi_base&state=login#wechat_redirect";
                        context.Result = new RedirectResult(url);
                    } else {var url = $"https://api.weixin.qq.com/sns/oauth2/access_token?appid={appid}&secret={appsecret}&code={code.Value}&grant_type=authorization_code";var data = _http.Get(url);if (data.IndexOf("access_token", StringComparison.Ordinal) > 0) {
                            var accessToken =
                                JsonConvert.DeserializeObject<AccessTokenModel>(data);
                            var user = _userManager.Users.SingleOrDefault(c => c.WeChatUserOpenId == accessToken.openid);
                            if (user == null) {
                                httpContext.Response.Cookies.Append("openid", accessToken.openid, new CookieOptions {
                                    Expires = DateTime.Now.AddMinutes(60)
                                });
                                await next();
                            } else {
                                await _signInManager.SignInAsync(user, true);
                                context.Result = new RedirectResult("/");
                            }
                        } else {
                            var errCode =
                                JsonConvert.DeserializeObject<ErrCodeModel>(data);
                            _logger.LogError($"请求openId发生错误,错误代码:{errCode.errcode},错误消息:{errCode.errmsg}");
                            await next();
                        }
                    }
                } else {
                    await next();
                }
            }
        }

        protected class AccessTokenModel {
            public string access_token { get; set; }
            public string expires_in { get; set; }
            public string refresh_token { get; set; }
            public string openid { get; set; }
            public string scope { get; set; }
        }

        protected class ErrCodeModel {
            public string errcode { get; set; }
            public string errmsg { get; set; }
        }

        protected class UserInfo {
            public string openid { get; set; }
            public string nickname { get; set; }
            public string sex { get; set; }
            public string province { get; set; }
            public string city { get; set; }
            public string country { get; set; }
            public string headimgurl { get; set; }
            public string unionid { get; set; }
        }
    }
}