Pull element from an array of arrays MongoDb

Question

I am struggling to find the format for a query to remove an element (with an _id) from an array of arrays in Mongo.

When looking at the docs I couldn't find anything that was similar to what I have https://www.mongodb.com/docs/manual/reference/operator/update/pull/#up._S_pull

I know: the _id of the document in MySchema and the _id of the array element in innerArray.

I don't know the outerArray _id

Could someone help point out where I went wrong Thank you!

This is an example of the data (imagine the _id in ObjectId)

{
  outerArray:[
           {
             _id: 1
             innerArray: [{_id: 23, name: '123'}, {_id: 13, name: 'asdac'} ] 
           },
           {
             _id: 2,
             innerArray: [{_id: 16,name:'asf' }, {_id: 18,name:'asf' } ] 
           },
           {
            _id: 3,
            innerArray: [{_id: 136,name:'asf' }, {_id: 128,name:'asf' } ] 
           }
          ]
}

innerIds is an array of mongoose.Types.ObjectId

return MySchema.updateOne(
    {
      _id: documentId,
    },
    { $pull: { outerArray: { innerArray: { _id: { $in: innerIds } } } } },
  )
    .session(session)
    .exec()

Cast to ObjectId failed for value "{ '$in': [ 6284f3ce02e46e57fcc32e98, 6284f3c902e46e57fcc32e28 ] }" (type Object) at path "_id" — beginnersLuck.css
– beginnersLuck.css, Commented May 18, 2022 at 15:52
{ $pull: { 'outerArray.$. innerArray._id': { $in: innerIds } } } Tried this and got this "The positional operator did not find the match needed from the query." — beginnersLuck.css
– beginnersLuck.css, Commented May 18, 2022 at 15:54

Gibbs · Accepted Answer · 2022-05-18 15:57:03Z

1

db.collection.update({},
{
  $pull: {
    "outerArray.$[].innerArray": {//$[] does the trick
      _id: {
        $in: [
          16
        ]
      }
    }
  }
})

playground

answered May 18, 2022 at 15:57

Gibbs

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1 Comment

Gibbs Over a year ago

Reference helps to update arrays that contains embedded documents. It is different from $

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