Upsert and Multi flag in pymongo

Question

I am working on pymongo and this is my document: ``` { "_id": ObjectId("51211b57f07ddaa377000000"), "assignments": { "0": { "0": { "_id": ObjectId("5120dd7400a4453d58a0d0ec") }, "1": { "_id": ObjectId("5120dd8e00a4453d58a0d0ed") }, "2": { "_id": ObjectId("5120ddad00a4453d58a0d0ee") } } }, "password": "my_passwd", "username": "john" } ``` I would like to unset the "assignment" property of all such docs. I was able to achieve this on the mongo shell by doing: ``` db.users.update({}, {$unset: {"assignments": 1}}, false, true) ``` i.e., I passed the upsert and multi flag as the last two parameters to the update function function on users collection. However I did this with pymongo: ``` db.users.update({}, {"$unset": {"assignments": 1}}, False, True) ``` But the python interpreter threw an error as follows: ``` File "notes/assignment.py", line 34, in <module> db.users.update({}, {"$unset": {"assignments": 1}}, False, True) File "/usr/local/lib/python2.7/dist-packages/pymongo/collection.py"…

Accepted Answer

The problem is that the two flags you are passing in aren't `upsert` and `multi`. Based on the documentation of PyMongo's `Collection.update` (found here), it looks like you might be passing in values for the `upsert` and `manipulate` options, although I am not certain.

All you have to do to solve this is use one of Python's most awesome features: named arguments. By specifying which options you are passing to `update`, you add clarity to your code in addition to making sure accidents like this don't happen.

In this case, we want to pass the options `upsert=False` and `multi=True`.

```
db.users.update({}, { "$unset": { "assignments": 1 } }, upsert=False, multi=True)
```

Upsert and Multi flag in pymongo

Solution

Problem