Why is my Mongodb aggregation pipeline updateOne() working in compass, but not working in my node driver

[steevej (Steeve Juneau)]

@Wayne_Barker

So shouldn’t it only be updating one?

An aggregation does not update the original document and since you are calling updateOne, I assume that you want to update the original document. So whatever what you end up doing in your aggregation with limit:1 or not, your original document will not be updated.

I was able to update all wieghts.$.spotsAvailable by using the arrayFilters:

{ "el2" : { "userId" : "empty" , "name" : "empty" } }

I still do not know how to set up a filter that test only one of the field of a sub-object.

I still do not know how to limit the update to a single element using arrayFilters.

The only way I could make work what I think you want to achieve (assign an available spot to a participant) is by modifying your model to

@steevej

{
  "_id" : 1 ,
  "weights": [
    {
      "spots": [ ] ,
      "weight": 12 ,
      "spotsAvailable" : 3
    },
    {
      "spots": [ ] ,
      "weight": 15 ,
      "spotsAvailable" : 2
    }
  ]
}

and update with

@steevej

query = {
    "_id" : 1 ,
    "weights" : { "$elemMatch" : { "weight" : 12 ,"spotsAvailable" : { "$gt" : 0 } }
}
update = {
    "$inc" : { "weights.$.spotAvailable" : -1} ,
    "$push" : { "weights.$.spots" : { name : "steevej" , "userId" : 369 } }
}
db.events.updateOne( query , update )