Convert MongoDB Collection to Array of Nested Object

Question

My mongo data are in the following format:

{ country: "Bangladesh", city: "Dhaka", name: "Jobayer", email: "[email protected]" }
{ country: "Bangladesh", city: "Dhaka", name: "Mehotaz", email: "[email protected]" }
{ country: "KSA", city: "Dammam", name: "Jabal", email: "[email protected]" }

I want to retrieve data like below:

[
    {
        country: 'Bangladesh',
        cities: [
            {
                city: 'Dhaka',
                contacts: [
                    {
                        name: 'Jobayer',
                        email: '[email protected]'
                    },
                    {
                        name: 'Mehotaz',
                        email: '[email protected]'
                    }
                ]
            }
        ]
    },
    {
        country: 'KSA',
        cities: [
            {
                city: 'Dammam',
                contacts: [
                    {
                        name: 'Jabal',
                        email: '[email protected]'
                    }
                ]
            }
        ]
    }
];

I have tried some group operations but could not get the expected result. Please provide your valuable suggestion on how can I achieve that.

Tom Slabbaert · Accepted Answer · 2021-04-12 08:38:34Z

3

What you want to do is $group twice, once on country x city and then on just the country, like so:

db.collection.aggregate([
  {
    $group: {
      _id: {
        country: "$country",
        city: "$city"
      },
      contacts: {
        $push: {
          name: "$name",
          email: "$email"
        }
      }
    }
  },
  {
    $group: {
      _id: "$_id.country",
      cities: {
        $push: {
          city: "$_id.city",
          contacts: "$contacts"
        }
      }
    }
  }
])

Mongo Playground

answered Apr 12, 2021 at 8:38

Tom Slabbaert

22.5k10 gold badges34 silver badges45 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Convert MongoDB Collection to Array of Nested Object

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related