Pymongo find and modify

For those that came here after Googling find_and_modify and discovered it is deprecated (in PyMongo version 3.0, I think), the replacement is find_one_and_update.

Let's say you have a collection called counters and want to increment one of the counters:

db.counters.find_one_and_update({"_id": "counter-id"}, {"$inc":{"sequence_value":1}})

If you want the new document returned, instead of the original pre-updated one, the parameter to pass is new and not, as most documentation states, returnNewDocument:

db.counters.find_one_and_update({"_id": "counter-id"}, {"$inc":{"sequence_value":1}}, new=True)

Note that the methods in this answer have been deprecated. See Sid Holland's answer for more details.

---

refer the documentation, for example

db.update({"_id": acs_num}, {"$set": mydata}, upsert = True)

or find_and_modify according to docs says Returns either the object before or after modification based on new parameter. If no objects match the query and upsert is false, returns None. If upserting and new is false, returns {}

for example:

In [1]: from pymongo import MongoClient

In [2]: client = MongoClient("mongodb://localhost:27017")
   ...: db = client["testdb"]
   ...: mycollection = db["mydb"]
   ...: 

In [3]: import datetime
   ...: post1 = {"author": "Mike", "text": "My first blog post!", "tags": ["mongodb", "python", "pymongo"], "date": datetime.datetime.utcnow()}
   ...: 

In [4]: mycollection.insert(post1)
Out[4]: ObjectId('535fd580c314f91d28c35ee1')

In [5]: [x for x in mycollection.find()]
Out[5]: 
[{u'_id': ObjectId('535fd580c314f91d28c35ee1'),
  u'author': u'Mike',
  u'date': datetime.datetime(2014, 4, 29, 16, 38, 15, 457000),
  u'tags': [u'mongodb', u'python', u'pymongo'],
  u'text': u'My first blog post!'}]

In [6]: mycollection.find_and_modify(query={'author':'Mike'}, update={"$set": {'author': "Mike2"}}, upsert=False, full_response= True)
Out[6]: 
{u'lastErrorObject': {u'n': 1, u'updatedExisting': True},
 u'ok': 1.0,
 u'value': {u'_id': ObjectId('535fd580c314f91d28c35ee1'),
  u'author': u'Mike',
  u'date': datetime.datetime(2014, 4, 29, 16, 38, 15, 457000),
  u'tags': [u'mongodb', u'python', u'pymongo'],
  u'text': u'My first blog post!'}}

In [7]: [ x for x in mycollection.find()]
Out[7]: 
[{u'_id': ObjectId('535fd580c314f91d28c35ee1'),
  u'author': u'Mike2',
  u'date': datetime.datetime(2014, 4, 29, 16, 38, 15, 457000),
  u'tags': [u'mongodb', u'python', u'pymongo'],
  u'text': u'My first blog post!'}]