cannot set headers after they are sent to the client Nodejs? - node.js

Question

im trying to make a create methode to create an user with sending email after creat account ,
when i test this method
cannot set headers after they are sent to the client Nodejs
My Method:
export function registerUser(req, res, next) {
// log the request body
console.log(JSON.stringify(req.body))
const { name, email, password, phone, role, level } = req.body
userModel.create(
{
name: name,
email: email,
password: password,
createdAd: Date.now(),
phone: phone,
photo: `${req.protocol}://${req.get('host')}/images/${
req.file.filename
}`,
level: 1,
role: role,
status: 0,
},
(err, result) => {
if (err){ next(err) ;}
else {
sendMail(req, res)
res.status(201).json({
message: 'User added successfully!',
})
}
}
)
}
Email Method
export function sendMail(req, res) {
var mailOptions = {
from: 'neublua.game10#gmail.com',
to: req.body.email,
subject: 'Sending Email using Node.js',
text: 'That was easy!',
}
transporter.sendMail(mailOptions, function (error, info) {
if (error)
res.status(500).json({
message: 'Error sending email',
})
else console.log('Email sent: ' + info.response)
})
}
i put res and req to can access to the email
how can i solve it

Answer 1

This error shows up when you send the response two times.
What express does is that it will only send the first response back to the client, while any responses after that won't be sent. That's basically how the HTTP protocol works, you send a request, you get one response back.
1 request = 1 response
So, the problem actually comes from here
You're saying:
sendMail()
and after that you're saying:
res.status(201).json({
message: 'User added successfully!',
})
where the sendMail is actually sending a response, because an error is happening when it tries to send the email look:
the following screenshot is inside your sending email middleware:
So, you shouldn't send a response twice, either send it here, or there.
What exactly are you trying to achieve? If it's an unimportant email you're trying to send such as the "welcome" email, then keep checking for an error if emails are failing to sent but remove the response from there, the client doesn't need to know that the "welcome" email had a problem while being sent.
If this is an important email, such as an email verification email, then, remove the response sending lines from the user creation middleware, and only send the response (Success or fail) inside the email middleware.