[英]Trying to check if a user exist in my mongodb before inserting a new user (To prevent multiple same-email registration)
使用快遞。 我正在嘗試創建一個處理 POST 請求的 .js 文件,以在插入到我的 MongoDB 之前檢查用戶是否存在。 我建立了 2 個 MongoClient 連接來處理不同的情況。 首先是檢查用戶是否存在。 如果用戶不存在,那么它將轉到第二個連接。 我無法理解我做錯了什么
代碼是:`
router.post('/', function(req, res, next) {
console.log("inside post method profile")
ssn = req.session;
ssn.firstName = req.body.fname;
ssn.lastName = req.body.lname;
ssn.userEmail = req.body.email;
ssn.userPass = req.body.pass;
let userExists = false;
MongoClient.connect(url, function(err, db) {
if (err) throw err;
let dbo = db.db("projectOne");
let myInfoLog = {
email: ssn.userEmail,
pass: ssn.userPass
};
// TRYING TO COUNTERCHECK IF A USER ALREADY EXISTS
dbo.collection("userInfo").findOne(myInfoLog, function(err, data) {
if (data.email) {
userExists = true;
ssn.signUpError = "User email already exists";
console.log("data returns an active email");
db.close();
res.redirect('/');
}
});
});
if (userExists == false) {
MongoClient.connect(url, function(err, db) {
if (err) throw err;
let dbo = db.db("projectOne");
let myInfoLog = {
email: ssn.userEmail,
pass: ssn.userPass
};
let myInfo = {
fname: ssn.firstName,
lname: ssn.lastName,
email: ssn.userEmail,
pass: ssn.userPass
};
dbo.collection("userInfo").insertOne(myInfo, function(err, data) {
if (err) throw err;
console.log("collection inserted");
// console.log(data.ops[0].fname);
// console.log(data.ops[0].lname);
// console.log(data.ops[0].email);
// console.log(data.ops[0].pass);
ssn.firstName = data.ops[0].fname;
ssn.lastName = data.ops[0].lname;
ssn.userEmail = data.ops[0].email;
ssn.userPass = data.ops[0].pass;
console.log("welcome! " + ssn.firstName + " " + ssn.lastName)
db.close();
});
res.redirect('/profile');
});
}
});
module.exports = router;
我收到一個錯誤:
Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
at ServerResponse.setHeader (_http_outgoing.js:485:11)
at ServerResponse.header (C:\Users\rousb\Desktop\Internship2020\P_01\node_modules\express\lib\response.js:767:10)
at ServerResponse.location (C:\Users\rousb\Desktop\Internship2020\P_01\node_modules\express\lib\response.js:884:15)
at ServerResponse.redirect (C:\Users\rousb\Desktop\Internship2020\P_01\node_modules\express\lib\response.js:922:18)
at C:\Users\rousb\Desktop\Internship2020\P_01\routes\profile.js:47:15
at executeCallback (C:\Users\rousb\Desktop\Internship2020\P_01\node_modules\mongodb\lib\operations\execute_operation.js:70:5)
at handleCallback (C:\Users\rousb\Desktop\Internship2020\P_01\node_modules\mongodb\lib\utils.js:128:55)
at C:\Users\rousb\Desktop\Internship2020\P_01\node_modules\mongodb\lib\operations\find_one.js:29:9
at C:\Users\rousb\Desktop\Internship2020\P_01\node_modules\mongodb\lib\utils.js:731:5
at C:\Users\rousb\Desktop\Internship2020\P_01\node_modules\mongodb\lib\cursor.js:251:9 {
代碼:'ERR_HTTP_HEADERS_SENT'
您正在同時執行 2 個異步操作。 他們最終都試圖res.redirect('...');
一旦用戶已被重定向,您就無法重定向。 您的if (userExists == false) {
在您執行上述塊中的檢查之前執行。
你可以像這樣鏈接你的回調:
router.post('/', function(req, res, next) {
ssn = req.session;
ssn.firstName = req.body.fname;
ssn.lastName = req.body.lname;
ssn.userEmail = req.body.email;
ssn.userPass = req.body.pass;
MongoClient.connect(url, function(err, db) {
if (err) throw err;
let dbo = db.db("projectOne");
let myInfoLog = {
email: ssn.userEmail // Don't include the password!
};
// Check if email exists
dbo.collection("userInfo").findOne(myInfoLog, function(err, data) {
if (data.email) {
ssn.signUpError = "User email already exists";
console.log("data returns an active email");
db.close();
res.redirect('/');
} else {
const myInfo = {
fname: ssn.firstName,
lname: ssn.lastName,
email: ssn.userEmail,
pass: ssn.userPass
};
// Insert user
dbo.collection("userInfo").insertOne(myInfo, function(err, data) {
if (err) throw err;
console.log("collection inserted");
ssn.firstName = data.ops[0].fname;
ssn.lastName = data.ops[0].lname;
ssn.userEmail = data.ops[0].email;
ssn.userPass = data.ops[0].pass;
console.log("welcome! " + ssn.firstName + " " + ssn.lastName);
db.close();
res.redirect('/profile');
});
}
});
});
});
module.exports = router;
您應該將if (userExists == false) {
塊移動到第一次查找中。
dbo
.collection("userInfo")
.findOne(myInfoLog, function(err, data) {
if (data.email) {
// handle case where user already exists
} else {
// handle case where user doesn't exist yet
}
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