CODEWITHSUNDEEP
mongodbmongodb-query
zeus
zeus

Reputation: 13345

how to add a dot (.) inside a field name?

When I run this command :

db.runCommand( 

  {
    aggregate:"myColl",
    pipeline:[
      {
        $group:{
          _id:{os_name:"$os_name",os_version:"$os_version"},
          "events.login":{$sum:"$events.login"},
          count:{$sum:NumberInt(1)}}
      }
    ],
    cursor:{}
  }

 )

I receive the error:

The field name 'events.login' cannot contain '.'

How can i do to keep the '.' in the returned field name (ie: events.login)

Upvotes: 0

Views: 174

Answers (1)

whoami - fakeFaceTrueSoul
whoami - fakeFaceTrueSoul

Reputation: 17915

It's not quiet clear what you're trying to do, So look at these :

Error :

The field name 'events.login' cannot contain '.'

It's because as in $group stage when it creates a new field on each document for a given name, You'll not be able to create it like this : "events.login" means cannot create a sub-doc it has to be an object to a top level field events basically you can not use . notation, So to make it work you need to have one more stage like this :

db.collection.aggregate([{
    $group: {
        _id: { os_name: "$os_name", os_version: "$os_version" },
        "events": { $sum: "$events.login" },
        count: { $sum: NumberInt(1) }
    }
}, { $addFields: { 'events.login': '$events' } }])

Test : MongoDB-Playground

If in a case you need to update login field inside events field & to retain all other fields inside events, try below query which would get last document in iteration of each _id (this will last document inserted to DB on that _id criteria) & append login to it :

db.collection.aggregate([{
    $group: {
        _id: { os_name: "$os_name", os_version: "$os_version" },
        "login": { $sum: "$events.login" }, 'events': { $last: '$events' },
        count: { $sum: NumberInt(1) }
    }
}, { $addFields: { 'events.login': '$login' } }, { $project: { login: 0 } }])

Test : MongoDB-Playground

Upvotes: 1

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