Node.js UnhandledPromiseRejectionWarning: Error: Can't set headers after they are sent
0
I'm new to node.js and want to send out dataof User and Match in a single response by querying mongodb twice .
router.get('/preview/', checkAuth, (req, res)=> {
const errors = {};
const match = {}
User.findOne({_id: req.user.id})
.then(user => {
if (!user) {
return res.status(404).json({errors: 'Could not find a user' });
}
Match.findOne({ user: req.user.id }).then(m => {
console.log('match found!');
match = m;
}).catch(err=> res.status(404).json(err)); // <-error occures here
res.status(200).json({user, match});
})
.catch(err=> res.status(404).json(err));
});
But I get this error:
(node:8056) UnhandledPromiseRejectionWarning: Error: Can't set headers after they are sent.
How can I fix it?
node.js
asked Nov 20 '18 at 4:48
BabrBabr
31019
add a comment |
0
I'm new to node.js and want to send out dataof User and Match in a single response by querying mongodb twice .
router.get('/preview/', checkAuth, (req, res)=> {
const errors = {};
const match = {}
User.findOne({_id: req.user.id})
.then(user => {
if (!user) {
return res.status(404).json({errors: 'Could not find a user' });
}
Match.findOne({ user: req.user.id }).then(m => {
console.log('match found!');
match = m;
}).catch(err=> res.status(404).json(err)); // <-error occures here
res.status(200).json({user, match});
})
.catch(err=> res.status(404).json(err));
});
But I get this error:
(node:8056) UnhandledPromiseRejectionWarning: Error: Can't set headers after they are sent.
How can I fix it?
node.js
asked Nov 20 '18 at 4:48
BabrBabr
31019
add a comment |
0
0
0
I'm new to node.js and want to send out dataof User and Match in a single response by querying mongodb twice .
router.get('/preview/', checkAuth, (req, res)=> {
const errors = {};
const match = {}
User.findOne({_id: req.user.id})
.then(user => {
if (!user) {
return res.status(404).json({errors: 'Could not find a user' });
}
Match.findOne({ user: req.user.id }).then(m => {
console.log('match found!');
match = m;
}).catch(err=> res.status(404).json(err)); // <-error occures here
res.status(200).json({user, match});
})
.catch(err=> res.status(404).json(err));
});
But I get this error:
(node:8056) UnhandledPromiseRejectionWarning: Error: Can't set headers after they are sent.
How can I fix it?
node.js
asked Nov 20 '18 at 4:48
BabrBabr
31019
I'm new to node.js and want to send out dataof User and Match in a single response by querying mongodb twice .
router.get('/preview/', checkAuth, (req, res)=> {
const errors = {};
const match = {}
User.findOne({_id: req.user.id})
.then(user => {
if (!user) {
return res.status(404).json({errors: 'Could not find a user' });
}
Match.findOne({ user: req.user.id }).then(m => {
console.log('match found!');
match = m;
}).catch(err=> res.status(404).json(err)); // <-error occures here
res.status(200).json({user, match});
})
.catch(err=> res.status(404).json(err));
});
But I get this error:
(node:8056) UnhandledPromiseRejectionWarning: Error: Can't set headers after they are sent.
How can I fix it?
node.js
node.js
asked Nov 20 '18 at 4:48
BabrBabr
31019
asked Nov 20 '18 at 4:48
BabrBabr
31019
asked Nov 20 '18 at 4:48
BabrBabr
31019
asked Nov 20 '18 at 4:48
BabrBabr
31019
asked Nov 20 '18 at 4:48
BabrBabr
31019
31019
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
2
Please have a look at the comments added in your code.
router.get('/preview/', checkAuth, (req, res)=> {
const errors = {};
const match = {}
User.findOne({_id: req.user.id})
.then(user => {
if (!user) {
return res.status(404).json({errors: 'Could not find a user' });
}
Match.findOne({ user: req.user.id }).then(m => {
console.log('match found!');
match = m;
}).catch(err=> res.status(404).json(err)); // <-error occures here because you sent the response if error occurs
res.status(200).json({user, match}); // this will be executed even if there is an error so it will again try to send the response
})
.catch(err=> res.status(404).json(err));
});
Improved code:
router.get('/preview/', checkAuth, (req, res) => {
const errors = {};
User.findOne({ _id: req.user.id })
.then((user) => {
if (!user) {
return res.status(404).json({ errors: 'Could not find a user' });
}
Match.findOne({ user: req.user.id })
.then((m) => {
console.log('match found!');
res.status(200).json({ user, m }); // send the success response when the match found
})
.catch((err) => res.status(404).json(err)); // send the error response when erro thrown
})
.catch((err) => res.status(404).json(err));
});
answered Nov 20 '18 at 4:53
Niral MunjariyaNiral Munjariya
792520
Well I changed the first line to a console.log. The error is gone, but now I getres data undefinedin the front end. Any ideas?
– Babr
Nov 20 '18 at 4:55
Does the improved code block works? I have added it in the answer.
– Niral Munjariya
Nov 20 '18 at 4:59
As I said the error gone by changing the first.catch((err) => res.status(404).json(err))to.catch(err=> console.log(err));. But now I getTypeError: Assignment to constant variable.error instead.
– Babr
Nov 20 '18 at 5:00
1
That is because you try to re-assign a value to a const variable "match", just change it to let and it should work.
– Niral Munjariya
Nov 20 '18 at 5:16
Please check the improved code block, I have updated it.
– Niral Munjariya
Nov 20 '18 at 5:19
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
2
Please have a look at the comments added in your code.
router.get('/preview/', checkAuth, (req, res)=> {
const errors = {};
const match = {}
User.findOne({_id: req.user.id})
.then(user => {
if (!user) {
return res.status(404).json({errors: 'Could not find a user' });
}
Match.findOne({ user: req.user.id }).then(m => {
console.log('match found!');
match = m;
}).catch(err=> res.status(404).json(err)); // <-error occures here because you sent the response if error occurs
res.status(200).json({user, match}); // this will be executed even if there is an error so it will again try to send the response
})
.catch(err=> res.status(404).json(err));
});
Improved code:
router.get('/preview/', checkAuth, (req, res) => {
const errors = {};
User.findOne({ _id: req.user.id })
.then((user) => {
if (!user) {
return res.status(404).json({ errors: 'Could not find a user' });
}
Match.findOne({ user: req.user.id })
.then((m) => {
console.log('match found!');
res.status(200).json({ user, m }); // send the success response when the match found
})
.catch((err) => res.status(404).json(err)); // send the error response when erro thrown
})
.catch((err) => res.status(404).json(err));
});
answered Nov 20 '18 at 4:53
Niral MunjariyaNiral Munjariya
792520
Well I changed the first line to a console.log. The error is gone, but now I getres data undefinedin the front end. Any ideas?
– Babr
Nov 20 '18 at 4:55
Does the improved code block works? I have added it in the answer.
– Niral Munjariya
Nov 20 '18 at 4:59
As I said the error gone by changing the first.catch((err) => res.status(404).json(err))to.catch(err=> console.log(err));. But now I getTypeError: Assignment to constant variable.error instead.
– Babr
Nov 20 '18 at 5:00
1
That is because you try to re-assign a value to a const variable "match", just change it to let and it should work.
– Niral Munjariya
Nov 20 '18 at 5:16
Please check the improved code block, I have updated it.
– Niral Munjariya
Nov 20 '18 at 5:19
add a comment |
2
Please have a look at the comments added in your code.
router.get('/preview/', checkAuth, (req, res)=> {
const errors = {};
const match = {}
User.findOne({_id: req.user.id})
.then(user => {
if (!user) {
return res.status(404).json({errors: 'Could not find a user' });
}
Match.findOne({ user: req.user.id }).then(m => {
console.log('match found!');
match = m;
}).catch(err=> res.status(404).json(err)); // <-error occures here because you sent the response if error occurs
res.status(200).json({user, match}); // this will be executed even if there is an error so it will again try to send the response
})
.catch(err=> res.status(404).json(err));
});
Improved code:
router.get('/preview/', checkAuth, (req, res) => {
const errors = {};
User.findOne({ _id: req.user.id })
.then((user) => {
if (!user) {
return res.status(404).json({ errors: 'Could not find a user' });
}
Match.findOne({ user: req.user.id })
.then((m) => {
console.log('match found!');
res.status(200).json({ user, m }); // send the success response when the match found
})
.catch((err) => res.status(404).json(err)); // send the error response when erro thrown
})
.catch((err) => res.status(404).json(err));
});
answered Nov 20 '18 at 4:53
Niral MunjariyaNiral Munjariya
792520
Well I changed the first line to a console.log. The error is gone, but now I getres data undefinedin the front end. Any ideas?
– Babr
Nov 20 '18 at 4:55
Does the improved code block works? I have added it in the answer.
– Niral Munjariya
Nov 20 '18 at 4:59
As I said the error gone by changing the first.catch((err) => res.status(404).json(err))to.catch(err=> console.log(err));. But now I getTypeError: Assignment to constant variable.error instead.
– Babr
Nov 20 '18 at 5:00
1
That is because you try to re-assign a value to a const variable "match", just change it to let and it should work.
– Niral Munjariya
Nov 20 '18 at 5:16
Please check the improved code block, I have updated it.
– Niral Munjariya
Nov 20 '18 at 5:19
add a comment |
2
2
2
Please have a look at the comments added in your code.
router.get('/preview/', checkAuth, (req, res)=> {
const errors = {};
const match = {}
User.findOne({_id: req.user.id})
.then(user => {
if (!user) {
return res.status(404).json({errors: 'Could not find a user' });
}
Match.findOne({ user: req.user.id }).then(m => {
console.log('match found!');
match = m;
}).catch(err=> res.status(404).json(err)); // <-error occures here because you sent the response if error occurs
res.status(200).json({user, match}); // this will be executed even if there is an error so it will again try to send the response
})
.catch(err=> res.status(404).json(err));
});
Improved code:
router.get('/preview/', checkAuth, (req, res) => {
const errors = {};
User.findOne({ _id: req.user.id })
.then((user) => {
if (!user) {
return res.status(404).json({ errors: 'Could not find a user' });
}
Match.findOne({ user: req.user.id })
.then((m) => {
console.log('match found!');
res.status(200).json({ user, m }); // send the success response when the match found
})
.catch((err) => res.status(404).json(err)); // send the error response when erro thrown
})
.catch((err) => res.status(404).json(err));
});
answered Nov 20 '18 at 4:53
Niral MunjariyaNiral Munjariya
792520
Please have a look at the comments added in your code.
router.get('/preview/', checkAuth, (req, res)=> {
const errors = {};
const match = {}
User.findOne({_id: req.user.id})
.then(user => {
if (!user) {
return res.status(404).json({errors: 'Could not find a user' });
}
Match.findOne({ user: req.user.id }).then(m => {
console.log('match found!');
match = m;
}).catch(err=> res.status(404).json(err)); // <-error occures here because you sent the response if error occurs
res.status(200).json({user, match}); // this will be executed even if there is an error so it will again try to send the response
})
.catch(err=> res.status(404).json(err));
});
Improved code:
router.get('/preview/', checkAuth, (req, res) => {
const errors = {};
User.findOne({ _id: req.user.id })
.then((user) => {
if (!user) {
return res.status(404).json({ errors: 'Could not find a user' });
}
Match.findOne({ user: req.user.id })
.then((m) => {
console.log('match found!');
res.status(200).json({ user, m }); // send the success response when the match found
})
.catch((err) => res.status(404).json(err)); // send the error response when erro thrown
})
.catch((err) => res.status(404).json(err));
});
answered Nov 20 '18 at 4:53
Niral MunjariyaNiral Munjariya
792520
edited Nov 20 '18 at 5:17
answered Nov 20 '18 at 4:53
Niral MunjariyaNiral Munjariya
792520
answered Nov 20 '18 at 4:53
Niral MunjariyaNiral Munjariya
792520
answered Nov 20 '18 at 4:53
Niral MunjariyaNiral Munjariya
792520
792520
Well I changed the first line to a console.log. The error is gone, but now I getres data undefinedin the front end. Any ideas?
– Babr
Nov 20 '18 at 4:55
Does the improved code block works? I have added it in the answer.
– Niral Munjariya
Nov 20 '18 at 4:59
As I said the error gone by changing the first.catch((err) => res.status(404).json(err))to.catch(err=> console.log(err));. But now I getTypeError: Assignment to constant variable.error instead.
– Babr
Nov 20 '18 at 5:00
1
That is because you try to re-assign a value to a const variable "match", just change it to let and it should work.
– Niral Munjariya
Nov 20 '18 at 5:16
Please check the improved code block, I have updated it.
– Niral Munjariya
Nov 20 '18 at 5:19
add a comment |
Well I changed the first line to a console.log. The error is gone, but now I getres data undefinedin the front end. Any ideas?
– Babr
Nov 20 '18 at 4:55
Does the improved code block works? I have added it in the answer.
– Niral Munjariya
Nov 20 '18 at 4:59
As I said the error gone by changing the first.catch((err) => res.status(404).json(err))to.catch(err=> console.log(err));. But now I getTypeError: Assignment to constant variable.error instead.
– Babr
Nov 20 '18 at 5:00
1
That is because you try to re-assign a value to a const variable "match", just change it to let and it should work.
– Niral Munjariya
Nov 20 '18 at 5:16
Please check the improved code block, I have updated it.
– Niral Munjariya
Nov 20 '18 at 5:19
Well I changed the first line to a console.log. The error is gone, but now I get
res data undefined in the front end. Any ideas?– Babr
Nov 20 '18 at 4:55
Well I changed the first line to a console.log. The error is gone, but now I get
res data undefined in the front end. Any ideas?– Babr
Nov 20 '18 at 4:55
Does the improved code block works? I have added it in the answer.
– Niral Munjariya
Nov 20 '18 at 4:59
Does the improved code block works? I have added it in the answer.
– Niral Munjariya
Nov 20 '18 at 4:59
As I said the error gone by changing the first
.catch((err) => res.status(404).json(err)) to .catch(err=> console.log(err)); . But now I get TypeError: Assignment to constant variable. error instead.– Babr
Nov 20 '18 at 5:00
As I said the error gone by changing the first
.catch((err) => res.status(404).json(err)) to .catch(err=> console.log(err)); . But now I get TypeError: Assignment to constant variable. error instead.– Babr
Nov 20 '18 at 5:00
1
1
That is because you try to re-assign a value to a const variable "match", just change it to let and it should work.
– Niral Munjariya
Nov 20 '18 at 5:16
That is because you try to re-assign a value to a const variable "match", just change it to let and it should work.
– Niral Munjariya
Nov 20 '18 at 5:16
Please check the improved code block, I have updated it.
– Niral Munjariya
Nov 20 '18 at 5:19
Please check the improved code block, I have updated it.
– Niral Munjariya
Nov 20 '18 at 5:19
add a comment |
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