MongoDB, how to add a unique index called "id"

Question

I'm trying to add an index called "id" in my collection but it returns:

E11000 duplicate key error index: collec.items.$id_1 dup key: { : -27 }

Is it before of a conflict between _id and id? I really need the id field to be unique to avoid duplicates.

If you already have duplicate values in `id` field, remove them first and then try to add index — Ali Dehghani, Jun 09 '16 at 07:53

score 1 · Answer 1 · answered Jun 09 '16 at 08:04

Is it before of a conflict between _id and id?

No, it's not a conflict. You're adding a unique index on a field that currently contains duplicate values (one of these duplicates is -27), so MongoDB complains with:

E11000 duplicate key error index: collec.items.$id_1 dup key: { : -27 }

First remove the duplicate values and then try to add the index.

score 0 · Answer 2 · edited May 23 '17 at 10:34

Are you trying to update the existing _id with id ? Then mongo doesn't allow to do so. Instead create a document. _id is unique identifier for mongo documents.

Creating the document with the unique id as you require,

>use db.docname.insert( { id:12345, name:"name" })
WriteResult({ "nInserted" : 1 })
>db.idreplace.find().pretty()
{
        "_id" : ObjectId("57592f1f2aa2b6057f3286ce"),
        "id" : 12345,
        "name" : "name"
}

OR

to add id to the existing document follow: Add new field to a collection in MongoDB

MongoDB, how to add a unique index called "id"

2 Answers2