MongoDB-and-SQL/using_find_and_modify.py at master · Pidem/MongoDB-and-SQL · GitHub

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# Andrew Erlichson
# MongoDB, Inc. Copyright 2015 - All Rights Reserved

import pymongo

# gets the next number in a sequence
def get_next_sequence_number(name):
    connection = pymongo.MongoClient("mongodb://localhost")

    db = connection.test
    counters = db.counters

    # let's get ourselves a sequence number
    # note there are two other varients of this call as well:
    # find_one_and_delete
    # find_one_and_replace
    # all these map to the the command find_and_modify


    try:
        counter = counters.find_one_and_update(filter={'type':name},
                                               update={'$inc':{'value':-1}},
                                               upsert=True,
                                               return_document=pymongo.ReturnDocument.AFTER)
    except Exception as e:
        print "Exception: ", type(e), e

    counter_value = counter['value']
    return counter_value


print get_next_sequence_number('uid')
print get_next_sequence_number('uid')
print get_next_sequence_number('uid')