Let me start by saying that I’m brand new to MongoDB. I only started a few days ago.

I have a collection of employees, one of the fields represents the phone number broken down into parts. It looks like this:

  {
    _id: ObjectId('666225dbe02f02db7f19465a'),
    lastName: 'Smith',
    firstName: 'John',
    middleInitial: '',
    email: '[email protected]',
    phone: [
      {
        international: '',
        area: '555',
        prefix: '555',
        number: '1234',
        ext: '',
        name: 'work'
      },
      {
        international: '',
        area: '555',
        prefix: '555',
        number: '2345',
        ext: '',
        name: 'cell'
      }
    ],
    address: {
      work: {
        city: 'New York',
        province: 'NY',
        buildingName: 'Empire State Building',
        address: '20 W 34th St.',
        postalCode: '10001',
        mailstop: '49B'
      }
    },
    positionId: ObjectId('666225dbe92f02db8f09465d')
  }

What I’m trying to achieve is to have the phone number regrouped inside each array element like this:

  {
[...]
    phone: [
      {
        international: '',
        area: '555',
        prefix: '555',
        number: '1234',
        ext: '',
        name: 'work',
        phone: '(555) 555-1234'
      },
      {
        international: '',
        area: '555',
        prefix: '555',
        number: '2345',
        ext: '',
        name: 'cell',
        phone: '(555) 555-2345'
      }
    ],
[...]
  }

I am using PHP so my code example will be in PHP. I tried a few things, but this is what I have right now.

$documents = $collection->aggregate([
  [
    '$addFields'=>[
      'phone.phone'=>[
        '$map'=>[
          'input'=> '$phone',
          'as'=> "p",
          'in'=>[
            '$concat'=>[
              "(", '$$p.area', ") ",
              '$$p.prefix', "-",
              '$$p.number',
              [
                '$cond'=> [
                  [
                    '$ne'=>[
                      '$$p.ext',
                      ''
                    ],
                  ],
                  [
                    '$concat'=>[
                      ' ext. ',
                      '$$p.ext',
                    ],
                  ],
                  ''
                ],
              ],
            ],
          ],
        ],
      ],
    ],
  ],
]);

Unfortunately, this returns an array of ALL phone numbers in EACH element of the phone array

  {
[...]
    phone: [
      {
        international: '',
        area: '555',
        prefix: '555',
        number: '1234',
        ext: '',
        name: 'work',
        phone: [ '(555) 555-1234', '(555) 555-2345' ]
      },
      {
        international: '',
        area: '555',
        prefix: '555',
        number: '2345',
        ext: '',
        name: 'cell',
        phone: [ '(555) 555-1234', '(555) 555-2345' ]
      }
    ],
[...]
  }

I tried using $project but I need to have ALL fields of the employee since not all employees have the same fields and project does not allow me to “return ALL fields by default”, I have to specify all of them. I also tried the $addFields (seen above), I tried using find instead of aggregate but I had the same result. I have searched for hours on the internet and the MongoDB documentation to find a solution but can’t find any (or don’t know how to type precisely what I’m looking for).

I know this can be done really easily in PHP, but I’m trying to learn MongoDB.

Thank you for any help you can provide.