javascript - Mongodb insert callback never called -

this question followup of this one , figured better ask new question post comment , necropost.

(tl;dr give solution _id when collection inserted)

i've tried .js bash script or in console doesn't seem work :

var latest; db.collec.insert({test:"yes"},function(err,newdoc){     latest = newdoc[0]._id;  }); 

the variable doesn't change. in console command returns writeresult({ "ninserted" : 1 }) lastest still void, , in js has same value before.

is there way id without node.js ? should switch node.js ?

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my bash script mongo --eval '<my whole javascript>'

you missing 1 piece in expression.

var latest; db.collec.insert({test:"yes"},function(err,newdoc){     latest = newdoc.ops[0]._id; }); 

newdoc contains entire response mongo.

newdoc.ops contains array of inserted row(s).

newdoc.insertedids contains array of id's of inserted row(s).

an alternative solution be:

var latest; db.collec.insert({test:"yes"},function(err,newdoc){     latest = newdoc.insertedids[0]; }); 

you can data without using node.js. can use mongodb shell. command prompt on system running mongo type mongo interactive shell. once there, run mongo commands:

> show dbs  //will list databases > use dbname  //will use database called dbname > show collections  //will list collections within current database > db.col.find({test: 'yes'});  //will retrieve document collection named col 'test' = 'yes' 

entire working javascript file:

var mongodb = require('mongodb').mongoclient;  mongodb.connect('mongodb://localhost:27017/testdb', function(err, db){    var collection = db.collection('collec');    collection.insert({'test': 'yes'}, function(err, results){       console.log(results.ops[0]._id);       db.close();    }); }); 

this can used query _id directly.

var mongodb = require('mongodb').mongoclient; var objectid = require('mongodb').objectid;  mongodb.connect('mongodb://localhost:27017/testdb', function(err, db){    var collection = db.collection('collec');    var id = objectid('583346693b3b904546ca175d');    collection.find({'_id': id}).toarray(function(err, results){       console.log(results);       db.close();    }); });