During insert : E11000 duplicate key error index

Question

I am using mongojs and Node.js to insert a document in mongodb. It is a REST API and there is only one instance of mongojs (with native drive). Everytime, there is an api call, SAME mongojs object is used to perform mongodb operations. Now, I get the following error when trying to insert a document.

{
name: "MongoError"
err: "E11000 duplicate key error index: testdb.userComment.$_id_ dup key: { :    ObjectId('51727190bb4ab52a80024c09') }"
code: 11000
n: 0
connectionId: 225
ok: 1
}

The document is always unique I tried db.userComment.getIndexs() and it shows the index is on _id . Can anyone help me how I can fix this problem ?

`_id` must be unique in MongoDB. If you have a new document, it's easiest if you just don't set the `_id` field and one will be automatically assigned by either the driver or the database. Either way, it will be unique. — WiredPrairie, Apr 21 '13 at 18:07

score 1 · Answer 1 · answered Apr 21 '13 at 16:58

1

I am not sure whether its a right fix, but everytime a document is inserted, I am explicitly creating a new ObjectID instead leaving the fate to mongodb driver. I used the following piece of code

commentData._id = require('mongodb').BSONPure.ObjectID();

answered Apr 21 '13 at 16:58

codejammer

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1
7
18

Is this an answer to your question, or additional information about your question? – WiredPrairie Apr 21 '13 at 18:06
It's also available here: `var id=require('mongodb').ObjectID()` – WiredPrairie Apr 21 '13 at 18:15
are you creating a new one? Have you looked at what's being assigned? Do you need a "new " in front of that? – Asya Kamsky Apr 22 '13 at 03:06
@wiredprairie I fixed using the above piece of code. But, I am unable to understand "why mongodb is not creating unique _id in this case" – codejammer Apr 22 '13 at 07:41
@AsyaKamsky Yes, I am creating a new one. I find that _id is cached somewhere and the same is being used when I am inserting a new record. – codejammer Apr 22 '13 at 07:42
hard to know what was wrong in your code since you didn't include any of it in the original question. – Asya Kamsky Apr 23 '13 at 05:28

score -1 · Answer 2 · edited May 23 '17 at 12:09

This question seems to be a duplicate of this one : Getting "err" : "E11000 duplicate key error when inserting into mongo using the Java driver

I found an answer on this page. I’m guessing your code looks something like this (greatly simplified)?:

doc = {} 
for i in xrange(2): 
    doc['i'] = i 
    collection.insert(doc)

The problem is that PyMongo injects an _id field into the document, if the _id field does not exist, before inserting it (_id is always generated client side with 10gen drivers). That means that the first time through the loop _id is added by the insert method. Since doc is defined outside the loop, each subsequent pass through the loop uses the same value for _id.

Solution:

Delete the key _id

for i in xrange(2): 
    doc['i'] = i 
    if '_id' in doc: 
        del doc['_id'] 
    collection.insert(doc)

Or create manually a new one:

from bson.objectid import ObjectId 
for i in xrange(2): 
    doc['i'] = i 
    doc['_id'] = ObjectId() 
    collection.insert(doc)

During insert : E11000 duplicate key error index

2 Answers2