Node.js 发送到客户端节点后无法设置标头

我正在编写一个react.js应用程序，就像一个博客，人们可以在这里发表文章，就像在媒体平台上一样。但是，当我的用户尝试登录他们的帐户时，我的express服务器返回一个错误，该错误表示应用程序无法在发送邮件后返回邮件头，但我不知道如何解决这个问题

我的代码：

app.post("/users/login", (req, res) => {

     var ReqUsername = req.body.username;
     var ReqPassword = req.body.password;

     userModel.find((err, docs) => {
          if(!err) {

               console.log(docs)

               docs.forEach(user => {
                    console.log(user)

                    var encryptedUsername = user.username;
                    var encryptedPassowrd = user.password;

                    var bytesUsername  = CryptoJS.AES.decrypt(encryptedUsername, <SECRET KEY>);
                    var bytesPassword  = CryptoJS.AES.decrypt(encryptedPassowrd, <SECRET KEY>);

                    var decryptedUsername = bytesUsername.toString(CryptoJS.enc.Utf8);
                    var decryptedPassword = bytesPassword.toString(CryptoJS.enc.Utf8);

                    if(decryptedUsername == ReqUsername) {
                         if(decryptedPassword == ReqPassword) {
                              res.json({
                                   sucesso: true,
                                   mensagem:"Login feito com sucesso",
                                   userId: user.userId
                              }).status(202)
                         }
                         else {
                              res.json({
                                   sucesso: false,
                                   mensagem:"Por favor, confira as suas informações e tente login novamente"
                              }).status(404)
                         }
                    }
                    else {
                         res.json({
                              sucesso: false,
                              mensagem:"Por favor, confira as suas informações e tente login novamente"
                         }).status(404)
                    }

               })
          }
          else {
               res.json("Error on check user database").status(500)
          }
     })
})

app.post（“/users/login”，（req，res）=>{
var ReqUsername=req.body.username；
var ReqPassword=req.body.password；
userModel.find（（错误，文档）=>{
如果（！err）{
console.log（文档）
docs.forEach（用户=>{
console.log（用户）
var encryptedUsername=user.username；
var encryptedPassowrd=user.password；
var bytesundername=CryptoJS.AES.decrypt（encryptedUsername，）；
var bytesPassword=CryptoJS.AES.decrypt（encryptedPassowrd，）；
var decryptedUsername=byteUserName.toString（CryptoJS.enc.Utf8）；
var decryptedPassword=bytesPassword.toString（CryptoJS.enc.Utf8）；
if（decryptedUsername==ReqUsername）{
if（decryptedPassword==ReqPassword）{
res.json({
是的，
mensagem:“登录feito com successo”，
userId:user.userId
}).现状（202）
}
否则{
res.json({
sucesso:错，
策略：“赞成，确认为信息更新”
}).现状（404）
}
}
否则{
res.json({
sucesso:错，
策略：“赞成，确认为信息更新”
}).现状（404）
}
})
}
否则{
res.json（“检查用户数据库时出错”）。状态（500）
}
})
})

使用post登录url后，我总是收到以下错误：

2021-02-20T14:16:38.847139+00:00 app[web.1]: Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
2021-02-20T14:16:38.847140+00:00 app[web.1]:     at ServerResponse.setHeader (_http_outgoing.js:558:11)
2021-02-20T14:16:38.847140+00:00 app[web.1]:     at ServerResponse.header (/app/node_modules/express/lib/response.js:771:10)
2021-02-20T14:16:38.847141+00:00 app[web.1]:     at ServerResponse.send (/app/node_modules/express/lib/response.js:170:12)
2021-02-20T14:16:38.847141+00:00 app[web.1]:     at ServerResponse.json (/app/node_modules/express/lib/response.js:267:15)
2021-02-20T14:16:38.847142+00:00 app[web.1]:     at /app/main.js:79:35
2021-02-20T14:16:38.847142+00:00 app[web.1]:     at Array.forEach (<anonymous>)
2021-02-20T14:16:38.847142+00:00 app[web.1]:     at /app/main.js:65:21
2021-02-20T14:16:38.847143+00:00 app[web.1]:     at /app/node_modules/mongoose/lib/model.js:4857:16
2021-02-20T14:16:38.847143+00:00 app[web.1]:     at /app/node_modules/mongoose/lib/model.js:4857:16
2021-02-20T14:16:38.847144+00:00 app[web.1]:     at /app/node_modules/mongoose/lib/helpers/promiseOrCallback.js:24:16
2021-02-20T14:16:38.847144+00:00 app[web.1]:     at /app/node_modules/mongoose/lib/model.js:4880:21
2021-02-20T14:16:38.847144+00:00 app[web.1]:     at /app/node_modules/mongoose/lib/query.js:4399:11
2021-02-20T14:16:38.847145+00:00 app[web.1]:     at /app/node_modules/kareem/index.js:136:16
2021-02-20T14:16:38.847145+00:00 app[web.1]:     at processTicksAndRejections (internal/process/task_queues.js:75:11)
2021-02-20T14:16:38.847146+00:00 app[web.1]: Emitted 'error' event on Function instance at:
2021-02-20T14:16:38.847146+00:00 app[web.1]:     at /app/node_modules/mongoose/lib/model.js:4859:13
2021-02-20T14:16:38.847146+00:00 app[web.1]:     at /app/node_modules/mongoose/lib/helpers/promiseOrCallback.js:24:16
2021-02-20T14:16:38.847147+00:00 app[web.1]:     [... lines matching original stack trace ...]
2021-02-20T14:16:38.847147+00:00 app[web.1]:     at processTicksAndRejections (internal/process/task_queues.js:75:11) {
2021-02-20T14:16:38.847147+00:00 app[web.1]:   code: 'ERR_HTTP_HEADERS_SENT'
2021-02-20T14:16:38.847148+00:00 app[web.1]: }

2021-02-20T14:16:38.847139+00:00应用程序[web.1]：错误[ERR\u HTTP\u HEADERS\u SENT]：发送到客户端后无法设置头
2021-02-20T14:16:38.847140+00:00应用程序[web.1]：位于ServerResponse.setHeader（_http_outgoing.js:558:11）
2021-02-20T14:16:38.847140+00:00应用程序[web.1]：位于ServerResponse.header（/app/node_modules/express/lib/response.js:771:10）
2021-02-20T14:16:38.847141+00:00app[web.1]：在ServerResponse.send（/app/node\u modules/express/lib/response.js:170:12）
2021-02-20T14:16:38.847141+00:00app[web.1]：位于ServerResponse.json（/app/node_modules/express/lib/response.js:267:15）
2021-02-20T14:16:38.847142+00:00应用程序[web.1]：at/app/main.js:79:35
2021-02-20T14:16:38.847142+00:00应用程序[web.1]：at Array.forEach（）
2021-02-20T14:16:38.847142+00:00应用程序[web.1]：at/app/main.js:65:21
2021-02-20T14:16:38.847143+00:00应用程序[web.1]：at/app/node_modules/mongoose/lib/model.js:4857:16
2021-02-20T14:16:38.847143+00:00应用程序[web.1]：at/app/node_modules/mongoose/lib/model.js:4857:16
2021-02-20T14:16:38.847144+00:00应用程序[web.1]：at/app/node_modules/mongoose/lib/helpers/promiseOrCallback.js:24:16
2021-02-20T14:16:38.847144+00:00应用程序[web.1]：at/app/node_modules/mongoose/lib/model.js:4880:21
2021-02-20T14:16:38.847144+00:00应用程序[web.1]：at/app/node_modules/mongoose/lib/query.js:4399:11
2021-02-20T14:16:38.847145+00:00应用程序[web.1]：at/app/node_modules/kareem/index.js:136:16
2021-02-20T14:16:38.847145+00:00应用程序[web.1]：在处理时检查和拒绝（内部/process/task_queues.js:75:11）
2021-02-20T14:16:38.847146+00:00应用程序[web.1]：在以下位置的函数实例上发出“错误”事件：
2021-02-20T14:16:38.847146+00:00应用程序[web.1]：at/app/node_modules/mongoose/lib/model.js:4859:13
2021-02-20T14:16:38.847146+00:00应用程序[web.1]：at/app/node_modules/mongoose/lib/helpers/promiseOrCallback.js:24:16
2021-02-20T14:16:38.847147+00:00应用程序[web.1]：[…与原始堆栈跟踪匹配的行…]
2021-02-20T14:16:38.847147+00:00应用程序[web.1]：在处理时检查和拒绝（内部/处理/任务队列.js:75:11）{
2021-02-20T14:16:38.847147+00:00应用程序[web.1]：代码：“ERR\u HTTP\u HEADERS\u SENT”
2021-02-20T14:16:38.847148+00:00应用程序[web.1]：}

我试着去掉一些反应，但效果不太好。

---

你们能帮我解决这个错误吗？

仅仅取消一些响应是不够的，每个请求只能有一个响应

app.post("/users/login", (req, res) => {
     var ReqUsername = req.body.username;
     var ReqPassword = req.body.password;
     userModel.find((err, docs) => {
          if(!err) {
               const user = docs.find(user => {
                    var bytesUsername  = CryptoJS.AES.decrypt(user.username, SECRET KEY);
                    var decryptedUsername = bytesUsername.toString(CryptoJS.enc.Utf8);
                    return decryptedUsername === ReqUsername;
               });
               
               if(!user) {
                    res.json({
                        sucesso: false,
                        mensagem:"Por favor, confira as suas informações e tente login novamente"
                    }).status(404)
               } else {
                    var bytesPassword  = CryptoJS.AES.decrypt(user.password, SECRET KEY);
                    var decryptedUsername = bytesUsername.toString(CryptoJS.enc.Utf8);
                    if(decryptedPassword == ReqPassword) {
                        res.json({
                            sucesso: true,
                            mensagem:"Login feito com sucesso",
                            userId: user.userId
                        }).status(202)
                    } else {
                        res.json({
                            sucesso: false,
                            mensagem:"Por favor, confira as suas informações e tente login novamente"
                        }).status(404)
                    }
               }
          } else {
               res.json("Error on check user database").status(500)
          }
     })
})

---

仅仅删除一些响应是不够的，每个请求只能有一个响应

app.post("/users/login", (req, res) => {
     var ReqUsername = req.body.username;
     var ReqPassword = req.body.password;
     userModel.find((err, docs) => {
          if(!err) {
               const user = docs.find(user => {
                    var bytesUsername  = CryptoJS.AES.decrypt(user.username, SECRET KEY);
                    var decryptedUsername = bytesUsername.toString(CryptoJS.enc.Utf8);
                    return decryptedUsername === ReqUsername;
               });
               
               if(!user) {
                    res.json({
                        sucesso: false,
                        mensagem:"Por favor, confira as suas informações e tente login novamente"
                    }).status(404)
               } else {
                    var bytesPassword  = CryptoJS.AES.decrypt(user.password, SECRET KEY);
                    var decryptedUsername = bytesUsername.toString(CryptoJS.enc.Utf8);
                    if(decryptedPassword == ReqPassword) {
                        res.json({
                            sucesso: true,
                            mensagem:"Login feito com sucesso",
                            userId: user.userId
                        }).status(202)
                    } else {
                        res.json({
                            sucesso: false,
                            mensagem:"Por favor, confira as suas informações e tente login novamente"
                        }).status(404)
                    }
               }
          } else {
               res.json("Error on check user database").status(500)
          }
     })
})

---

另外：您不应该加密密码，而是散列密码。应该没有办法恢复到用户输入的原始密码。另外：您不应该加密密码，而是哈希密码。应该没有办法回到用户输入的原始密码。非常感谢！非常感谢你！