python - Updating array in pymongo

Question

I am trying to maintain some counters in mongodb, so I need to update them periodically. I had the code working correctly when the data structure was a single level:

mlcol.find_one_and_update({"connip": conip}, {"$inc":{ts:1}}, upsert=True)

This resulted in an structure like this:

{
    "connip": "a",
    "1":1,
    "2":1,
    "3":1,
    "4":1
}

I want to convert the data structure to something like this:

{
    "connip": "a",
    "timeline": [
        {
            "timeslot": "1",
            "counter": 1
        },
        {
            "timeslot": "2",
            "counter": 1
        }
    ]
}

When I send this command:

mlcol.find_one_and_update({"connip": "a", "timeline.timeslot": "c"}, {"$inc":{"timeline.$.counter":1}}, upsert=True)

I get a correct update of the already existing counters, but If it is a new one, I get the following error:

pymongo.errors.OperationFailure: The positional operator did not find the match needed from the query.

It seems that it is necessary to first launch the insetr_one command:

ne = {"connip": "a","timeline":[{"timeslot": "c","counter":1},{"timeslot": "d","counter":1}]}
mlcol.insert_one(ne)

Is there any way of forcing the creation of the counter in case of this not existing previously? It is something that the command in the flat structure does correctly.

标签： pythonmongodbpymongo