Decode and Encode object ids in MongoDB using pymongo

objectids.py

# MongoDB Object ID decode
# Randall Shane, PhD
# RShane@BaseXVI.com
# BaseXVI.com
# 28 July 2014

'''MongoDB creates a unique id ('_id' key) for every document
which is a 12 byte object comprised of 4 parts as follows:

time stamp: 4 bytes
machine id: 3 bytes (MD5 hash of host name/mac)
process id: 2 bytes (first 2 bytes of the PID)
unique id: 3 byte integer value

Decode and encode as follows'''

from bson import objectid
from datetime import datetime
from pymongo import MongoClient


client = MongoClient('localhost', 27017)
db = client['test']
coll = db['testData']


def decode(oid):
    """Output is a dict containing:
    {   oid: (str)  Original Object ID,
        ets: (int)  Epoch TimeStamp,
        fts: (str)  Formatted TimeStamp,
        mid: (int)  Machine ID,
        pid: (int)  Process ID,
        uid: (int)  Unique ID }"""
    out = {}
    out['oid'] = str(objectid.ObjectId(oid))
    out['ets'] = int(out['oid'][0:8], 16)
    out['mid'] = int(out['oid'][8:14], 16)
    out['pid'] = int(out['oid'][14:18], 16)
    out['uid'] = int(out['oid'][18:], 16)

    try:
        out['fts'] = datetime.fromtimestamp(out['ets'])\
            .strftime('%d %b %Y %H:%M:%S')
    except:
        pass

    print out  # for display
    return out


def encode(data):
    """Input options is a dict of the 4 components
    {   ets: (int)  Epoch TimeStamp,
        mid: (int)  Machine ID,
        pid: (int)  Process ID,
        uid: (int)  Unique ID }"""
    oid = hex(data['ets']).replace('0x', '')
    oid += hex(data['mid']).replace('0x', '')
    oid += hex(data['pid']).replace('0x', '').zfill(4)
    oid += hex(data['uid']).replace('0x', '').zfill(6)

    print oid
    return oid


if __name__ == '__main__':
    # Decode on a collection created in the MongoDB shell by:
    # for (var i = 0; i <= 5; i++) db.testData.insert( { x : i } )
    print 'DECODE:'
    [decode(x['_id']) for x in coll.find({}, {'_id': 1})]

    # Encode test creating ObjectId using specific information
    print 'ENCODE:'
    data = {'ets': 1406557108, 'mid': 9999, 'pid': 8888, 'uid': 7777}
    encode(data)