How to get a callback on MongoDB collection.find()
When I run collection.find() in MongoDB/Node/Express, I'd like to get a callback when it's finished. What's the correct syntax for this?
function (id,callback) {
var o_id = new BSON.ObjectID(id);
db.open(function(err,db){
db.collection('users',function(err,collection){
collection.find({'_id':o_id},function(err,results){ //What's the correct callback synatax here?
db.close();
callback(results);
}) //find
}) //collection
}); //open
}
node.js mongodb express
edited Jul 26 '12 at 16:09
JohnnyHK
205k37433362
asked Jul 26 '12 at 2:40
John
1,81762641
add a comment |
When I run collection.find() in MongoDB/Node/Express, I'd like to get a callback when it's finished. What's the correct syntax for this?
function (id,callback) {
var o_id = new BSON.ObjectID(id);
db.open(function(err,db){
db.collection('users',function(err,collection){
collection.find({'_id':o_id},function(err,results){ //What's the correct callback synatax here?
db.close();
callback(results);
}) //find
}) //collection
}); //open
}
node.js mongodb express
edited Jul 26 '12 at 16:09
JohnnyHK
205k37433362
asked Jul 26 '12 at 2:40
John
1,81762641
add a comment |
When I run collection.find() in MongoDB/Node/Express, I'd like to get a callback when it's finished. What's the correct syntax for this?
function (id,callback) {
var o_id = new BSON.ObjectID(id);
db.open(function(err,db){
db.collection('users',function(err,collection){
collection.find({'_id':o_id},function(err,results){ //What's the correct callback synatax here?
db.close();
callback(results);
}) //find
}) //collection
}); //open
}
node.js mongodb express
edited Jul 26 '12 at 16:09
JohnnyHK
205k37433362
asked Jul 26 '12 at 2:40
John
1,81762641
When I run collection.find() in MongoDB/Node/Express, I'd like to get a callback when it's finished. What's the correct syntax for this?
function (id,callback) {
var o_id = new BSON.ObjectID(id);
db.open(function(err,db){
db.collection('users',function(err,collection){
collection.find({'_id':o_id},function(err,results){ //What's the correct callback synatax here?
db.close();
callback(results);
}) //find
}) //collection
}); //open
}
node.js mongodb express
node.js mongodb express
edited Jul 26 '12 at 16:09
JohnnyHK
205k37433362
asked Jul 26 '12 at 2:40
John
1,81762641
edited Jul 26 '12 at 16:09
JohnnyHK
205k37433362
asked Jul 26 '12 at 2:40
John
1,81762641
edited Jul 26 '12 at 16:09
JohnnyHK
205k37433362
edited Jul 26 '12 at 16:09
JohnnyHK
205k37433362
edited Jul 26 '12 at 16:09
JohnnyHK
205k37433362
205k37433362
asked Jul 26 '12 at 2:40
John
1,81762641
asked Jul 26 '12 at 2:40
John
1,81762641
asked Jul 26 '12 at 2:40
John
1,81762641
1,81762641
add a comment |
add a comment |
2 Answers
2
active
oldest
votes
That's the correct callback syntax, but what find provides to the callback is a Cursor, not an array of documents. So if you want your callback to provide results as an array of documents, call toArray on the cursor to return them:
collection.find({'_id':o_id}, function(err, cursor){
cursor.toArray(callback);
db.close();
});
Note that your function's callback still needs to provide an err parameter so that the caller knows whether the query worked or not.
2.x Driver Update
find now returns the cursor rather than providing it via a callback, so the typical usage can be simplified to:
collection.find({'_id': o_id}).toArray(function(err, results) {...});
Or in this case where a single document is expected, it's simpler to use findOne:
collection.findOne({'_id': o_id}, function(err, result) {...});
answered Jul 26 '12 at 3:09
JohnnyHK
205k37433362
So in this case where I'm only returning one result, it's normal to referencedata[0]in the controller?
– John
Jul 26 '12 at 3:13
2
In that case you'd want to usefindOneinstead, which directly provides the document to the callback. See mongodb.github.com/node-mongodb-native/api-generated/…
– JohnnyHK
Jul 26 '12 at 3:15
add a comment |
Based on JohnnyHK answer I simply wrapped my calls inside db.open() method and it worked. Thanks @JohnnyHK.
app.get('/answers', function (req, res){
db.open(function(err,db){ // <------everything wrapped inside this function
db.collection('answer', function(err, collection) {
collection.find().toArray(function(err, items) {
console.log(items);
res.send(items);
});
});
});
});
Hope it is helpful as an example.
edited Apr 30 '13 at 0:50
John
1,81762641
answered Apr 26 '13 at 15:58
Anmol Saraf
9,16974052
@John Thanks for formatting the code. I just missed them :)
– Anmol Saraf
Apr 30 '13 at 10:08
12
And they call it... callback hell! It begins...
– Karl Morrison
Mar 30 '15 at 0:45
1
i love you - - -
– timbo7io
Oct 6 '17 at 5:38
I am using same but I got db.open is not function error can you help me
– Pramod
Oct 10 at 8:02
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
That's the correct callback syntax, but what find provides to the callback is a Cursor, not an array of documents. So if you want your callback to provide results as an array of documents, call toArray on the cursor to return them:
collection.find({'_id':o_id}, function(err, cursor){
cursor.toArray(callback);
db.close();
});
Note that your function's callback still needs to provide an err parameter so that the caller knows whether the query worked or not.
2.x Driver Update
find now returns the cursor rather than providing it via a callback, so the typical usage can be simplified to:
collection.find({'_id': o_id}).toArray(function(err, results) {...});
Or in this case where a single document is expected, it's simpler to use findOne:
collection.findOne({'_id': o_id}, function(err, result) {...});
answered Jul 26 '12 at 3:09
JohnnyHK
205k37433362
So in this case where I'm only returning one result, it's normal to referencedata[0]in the controller?
– John
Jul 26 '12 at 3:13
2
In that case you'd want to usefindOneinstead, which directly provides the document to the callback. See mongodb.github.com/node-mongodb-native/api-generated/…
– JohnnyHK
Jul 26 '12 at 3:15
add a comment |
That's the correct callback syntax, but what find provides to the callback is a Cursor, not an array of documents. So if you want your callback to provide results as an array of documents, call toArray on the cursor to return them:
collection.find({'_id':o_id}, function(err, cursor){
cursor.toArray(callback);
db.close();
});
Note that your function's callback still needs to provide an err parameter so that the caller knows whether the query worked or not.
2.x Driver Update
find now returns the cursor rather than providing it via a callback, so the typical usage can be simplified to:
collection.find({'_id': o_id}).toArray(function(err, results) {...});
Or in this case where a single document is expected, it's simpler to use findOne:
collection.findOne({'_id': o_id}, function(err, result) {...});
answered Jul 26 '12 at 3:09
JohnnyHK
205k37433362
So in this case where I'm only returning one result, it's normal to referencedata[0]in the controller?
– John
Jul 26 '12 at 3:13
2
In that case you'd want to usefindOneinstead, which directly provides the document to the callback. See mongodb.github.com/node-mongodb-native/api-generated/…
– JohnnyHK
Jul 26 '12 at 3:15
add a comment |
That's the correct callback syntax, but what find provides to the callback is a Cursor, not an array of documents. So if you want your callback to provide results as an array of documents, call toArray on the cursor to return them:
collection.find({'_id':o_id}, function(err, cursor){
cursor.toArray(callback);
db.close();
});
Note that your function's callback still needs to provide an err parameter so that the caller knows whether the query worked or not.
2.x Driver Update
find now returns the cursor rather than providing it via a callback, so the typical usage can be simplified to:
collection.find({'_id': o_id}).toArray(function(err, results) {...});
Or in this case where a single document is expected, it's simpler to use findOne:
collection.findOne({'_id': o_id}, function(err, result) {...});
answered Jul 26 '12 at 3:09
JohnnyHK
205k37433362
That's the correct callback syntax, but what find provides to the callback is a Cursor, not an array of documents. So if you want your callback to provide results as an array of documents, call toArray on the cursor to return them:
collection.find({'_id':o_id}, function(err, cursor){
cursor.toArray(callback);
db.close();
});
Note that your function's callback still needs to provide an err parameter so that the caller knows whether the query worked or not.
2.x Driver Update
find now returns the cursor rather than providing it via a callback, so the typical usage can be simplified to:
collection.find({'_id': o_id}).toArray(function(err, results) {...});
Or in this case where a single document is expected, it's simpler to use findOne:
collection.findOne({'_id': o_id}, function(err, result) {...});
answered Jul 26 '12 at 3:09
JohnnyHK
205k37433362
edited Mar 2 '17 at 13:43
answered Jul 26 '12 at 3:09
JohnnyHK
205k37433362
answered Jul 26 '12 at 3:09
JohnnyHK
205k37433362
answered Jul 26 '12 at 3:09
JohnnyHK
205k37433362
205k37433362
So in this case where I'm only returning one result, it's normal to referencedata[0]in the controller?
– John
Jul 26 '12 at 3:13
2
In that case you'd want to usefindOneinstead, which directly provides the document to the callback. See mongodb.github.com/node-mongodb-native/api-generated/…
– JohnnyHK
Jul 26 '12 at 3:15
add a comment |
So in this case where I'm only returning one result, it's normal to referencedata[0]in the controller?
– John
Jul 26 '12 at 3:13
2
In that case you'd want to usefindOneinstead, which directly provides the document to the callback. See mongodb.github.com/node-mongodb-native/api-generated/…
– JohnnyHK
Jul 26 '12 at 3:15
So in this case where I'm only returning one result, it's normal to reference
data[0] in the controller?– John
Jul 26 '12 at 3:13
So in this case where I'm only returning one result, it's normal to reference
data[0] in the controller?– John
Jul 26 '12 at 3:13
2
2
In that case you'd want to use
findOne instead, which directly provides the document to the callback. See mongodb.github.com/node-mongodb-native/api-generated/…– JohnnyHK
Jul 26 '12 at 3:15
In that case you'd want to use
findOne instead, which directly provides the document to the callback. See mongodb.github.com/node-mongodb-native/api-generated/…– JohnnyHK
Jul 26 '12 at 3:15
add a comment |
Based on JohnnyHK answer I simply wrapped my calls inside db.open() method and it worked. Thanks @JohnnyHK.
app.get('/answers', function (req, res){
db.open(function(err,db){ // <------everything wrapped inside this function
db.collection('answer', function(err, collection) {
collection.find().toArray(function(err, items) {
console.log(items);
res.send(items);
});
});
});
});
Hope it is helpful as an example.
edited Apr 30 '13 at 0:50
John
1,81762641
answered Apr 26 '13 at 15:58
Anmol Saraf
9,16974052
@John Thanks for formatting the code. I just missed them :)
– Anmol Saraf
Apr 30 '13 at 10:08
12
And they call it... callback hell! It begins...
– Karl Morrison
Mar 30 '15 at 0:45
1
i love you - - -
– timbo7io
Oct 6 '17 at 5:38
I am using same but I got db.open is not function error can you help me
– Pramod
Oct 10 at 8:02
add a comment |
Based on JohnnyHK answer I simply wrapped my calls inside db.open() method and it worked. Thanks @JohnnyHK.
app.get('/answers', function (req, res){
db.open(function(err,db){ // <------everything wrapped inside this function
db.collection('answer', function(err, collection) {
collection.find().toArray(function(err, items) {
console.log(items);
res.send(items);
});
});
});
});
Hope it is helpful as an example.
edited Apr 30 '13 at 0:50
John
1,81762641
answered Apr 26 '13 at 15:58
Anmol Saraf
9,16974052
@John Thanks for formatting the code. I just missed them :)
– Anmol Saraf
Apr 30 '13 at 10:08
12
And they call it... callback hell! It begins...
– Karl Morrison
Mar 30 '15 at 0:45
1
i love you - - -
– timbo7io
Oct 6 '17 at 5:38
I am using same but I got db.open is not function error can you help me
– Pramod
Oct 10 at 8:02
add a comment |
Based on JohnnyHK answer I simply wrapped my calls inside db.open() method and it worked. Thanks @JohnnyHK.
app.get('/answers', function (req, res){
db.open(function(err,db){ // <------everything wrapped inside this function
db.collection('answer', function(err, collection) {
collection.find().toArray(function(err, items) {
console.log(items);
res.send(items);
});
});
});
});
Hope it is helpful as an example.
edited Apr 30 '13 at 0:50
John
1,81762641
answered Apr 26 '13 at 15:58
Anmol Saraf
9,16974052
Based on JohnnyHK answer I simply wrapped my calls inside db.open() method and it worked. Thanks @JohnnyHK.
app.get('/answers', function (req, res){
db.open(function(err,db){ // <------everything wrapped inside this function
db.collection('answer', function(err, collection) {
collection.find().toArray(function(err, items) {
console.log(items);
res.send(items);
});
});
});
});
Hope it is helpful as an example.
edited Apr 30 '13 at 0:50
John
1,81762641
answered Apr 26 '13 at 15:58
Anmol Saraf
9,16974052
edited Apr 30 '13 at 0:50
John
1,81762641
edited Apr 30 '13 at 0:50
John
1,81762641
edited Apr 30 '13 at 0:50
John
1,81762641
1,81762641
answered Apr 26 '13 at 15:58
Anmol Saraf
9,16974052
answered Apr 26 '13 at 15:58
Anmol Saraf
9,16974052
answered Apr 26 '13 at 15:58
Anmol Saraf
9,16974052
9,16974052
@John Thanks for formatting the code. I just missed them :)
– Anmol Saraf
Apr 30 '13 at 10:08
12
And they call it... callback hell! It begins...
– Karl Morrison
Mar 30 '15 at 0:45
1
i love you - - -
– timbo7io
Oct 6 '17 at 5:38
I am using same but I got db.open is not function error can you help me
– Pramod
Oct 10 at 8:02
add a comment |
@John Thanks for formatting the code. I just missed them :)
– Anmol Saraf
Apr 30 '13 at 10:08
12
And they call it... callback hell! It begins...
– Karl Morrison
Mar 30 '15 at 0:45
1
i love you - - -
– timbo7io
Oct 6 '17 at 5:38
I am using same but I got db.open is not function error can you help me
– Pramod
Oct 10 at 8:02
@John Thanks for formatting the code. I just missed them :)
– Anmol Saraf
Apr 30 '13 at 10:08
@John Thanks for formatting the code. I just missed them :)
– Anmol Saraf
Apr 30 '13 at 10:08
12
12
And they call it... callback hell! It begins...
– Karl Morrison
Mar 30 '15 at 0:45
And they call it... callback hell! It begins...
– Karl Morrison
Mar 30 '15 at 0:45
1
1
i love you - - -
– timbo7io
Oct 6 '17 at 5:38
i love you - - -
– timbo7io
Oct 6 '17 at 5:38
I am using same but I got db.open is not function error can you help me
– Pramod
Oct 10 at 8:02
I am using same but I got db.open is not function error can you help me
– Pramod
Oct 10 at 8:02
add a comment |
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