How to set unique id in mongodb with JavaScript

Question

I have data like this

Mywants:[
    {"title":"lap","rate":$20}
    {"title":"lap","rate":$20}
    {"title":"lap","rate":$20}
]

If I save new data into array(mywant) I should save with new unique id so how to save like that using javascript. So it should be look like:

Mywants:[
    {"title":"lap","rate":$20,_id:objectId("512640f3243c837c0e0004401}
    {"title":"lap","rate":$20,_id:objectId("512640f3243c837254000001}
    {"title":"lap","rate":$20,_id:objectId("512640f3243c8372540257001}}
]

To insert I am using command like

collection.update({"userid":1248787885},{$push:{"Mywant":{"title":"car","rate":$100}}});

JohnnyHK · Accepted Answer · 2013-02-23 13:38:31Z

2

As andyb notes, you have to generate the ObjectId for your new element by constructing a new one. But you don't need a separate library:

var mongodb = require('mongodb');
collection.update(
    {"userid":1248787885},
    {$push:{"Mywant":{
        _id: new mongodb.ObjectID(),
        "title":"car",
        "rate":$100
    }}});

Of course, $100 isn't a valid JavaScript type, but I assume you know that. It's also worth noting that Mongoose does this adding of _id fields to array elements for you, so that's another alternative.

edited Feb 23, 2013 at 13:38

answered Feb 22, 2013 at 14:08

JohnnyHK

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1 Comment

silvesterprabu Over a year ago

i have given same as above coding but it is showing error in semicolon.$push:{"Mywant":{ _id: new mongodb.ObjectID(); "title":"car", "rate":$100}} is this correct syntax or not? i think it is wrong syntax.

andyb · Accepted Answer · 2013-02-22 12:42:44Z

1

To generate mongoDB ObjectId in JavaScript you can use an existing library or implement the BSON ObjectId specification yourself. ObjectId.js is one such library and getting an Id is as simple as:

var objectId = new ObjectId();

edited Feb 22, 2013 at 12:42

answered Feb 22, 2013 at 8:25

andyb

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2 Comments

silvesterprabu Over a year ago

if i update new data into array it would not create new object id.so tell me correct answer.

andyb Over a year ago

I have updated my answer with a link to a JavaScript library for generating ObjectIds

user1629448 · Accepted Answer · 2013-02-22 09:52:26Z

0

In javascript there is one method called Math.random() it will create dynamic random number so you can modify this number as dynamic id.

answered Feb 22, 2013 at 9:52

user1629448

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