Add element to an array embedded inside a sub-document in MongoDB

Question

I have the following scheme on my MongoDB

{
    "weekday": 0,
    "hour":[
            {
                "hour": 14,
                "user": "user",
                "promoted": ["user1","user2","user3","user4"]
            },
            {
                "hour": 15,
                "user": "user",
                "promoted": ["user1","user2","user3","user4"]
            },
    ]
}

I want to add single elements to the "promoted" array of a certain hour, for example, add "user5" to the "promoted" array of the sub-document which has "hour": 14.

I have learned how to add new sub-documents to the hour array but not how to add a single element to the "promoted" array of a already existing sub-document. How could I do that?

see similar question Insert element into nested arrays in MongoDB — turivishal
– turivishal, Commented Jun 5, 2021 at 14:21

Jonathan Rodrigues Cardoso · Accepted Answer · 2021-06-05 14:54:43Z

0

In this case you need use $. Look here the documentation: https://docs.mongodb.com/manual/reference/operator/update/positional/

However, try this script:

db.yourCollection.update(
  {
    "hour.hour": 14
  },
  {
    $push: {"hour.$.promoted": "user5"}
  }
)

Result

{
    "_id" : ObjectId("60bb8e166cfda8327bbe08eb"),
    "weekday" : 0.0,
    "hour" : [ 
        {
            "hour" : 14.0,
            "user" : "user",
            "promoted" : [ "user1", "user2", "user3", "user4", "user5"]
        }, 
        {
            "hour" : 15.0,
            "user" : "user",
            "promoted" : ["user1", "user2", "user3", "user4"]
        }
    ]
}

answered Jun 5, 2021 at 14:54

Jonathan Rodrigues Cardoso

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2 Comments

turivishal Over a year ago

please don't post answer when you see any duplicate question comment in question, there are lots of similar questions. see same answer like your.

Jonathan Rodrigues Cardoso Over a year ago

@turivishal ok, sorry. I am a new contributor :D

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