Get position of selected document in collection [mongoDB]

mongodb collections find position
Saint picture Saint · May 30, 2012 · Viewed 16.1k times · Source

How to get position (index) of selected document in mongo collection?

E.g. this document: db.myCollection.find({"id":12345}) has index 3 in myCollection

myCollection:
    id: 12340, name: 'G'
    id: 12343, name: 'V'
    id: 12345, name: 'A'
    id: 12348, name: 'N'

Answer

DhruvPathak picture DhruvPathak · May 30, 2012

If your requirement is to find the position of the document irrespective of any order, that is not possible as MongoDb does not store the documents in specific order. However,if you want to know the index based on some field, say _id , you can use this method.

If you are strictly following auto increments in your _id field. You can count all the documents that have value less than that _id, say n , then n + 1 would be index of the document based on _id.

n = db.myCollection.find({"id": { "$lt" : 12345}}).count() ;

This would also be valid if documents are deleted from the collection.

Related questions

MongoDB Show all contents from all collections

Is it possible to show all collections and its contents in MongoDB? Is the only way to show one by one?

Read More
How can I rename a collection in MongoDB?

Is there a dead easy way to rename a collection in mongo? Something like: db.originalCollectionName.rename('newCollectionName'); And if not, what is the best way to go about effectively renaming one?

Read More
In MongoDB, if collection is dropped, indexes dropped automatically as well?

If I create a collection in Mongo, and after adding documents to this collection I use ensureIndex() to create an index on, say, a number field on a document in this collections, if I drop the collection, do I have …

Read More