Sub-document to new document along with existing main document

Working with Data
2

Hello, @AKASH_SKY! Welcome to the community!
Have a look at this aggregation:

db.your_collection.aggregate([
  {
    $group: {
      _id: null,
      usersDocs: {
        $push: {
          _id: '_id',
          first: '$first',
          last: '$last',
        },
      },
      addrDocs: {
        $push: '$addresses',
      },
    },
  },
  // flatten array in $addressDocs prop
  {
    $set: {
      addrDocs: {
        $reduce: {
          input: '$addrDocs',
          initialValue: [],
          in: {
            $concatArrays: ['$$value', '$$this'],
          },
        },
      },
    },
  },
]);

The above command will provide you with the result like this:

{ 
   usersDocs: [...],
   addrDocs: [...] 
}

This is, often, a better structure, as you group group all the objects of the same type in one array:

  • one array of users objects
  • and another one array is for addresses objects

Such approach, often, is more practical :wink:

But, of course, you can get array of mixed objects, by adding in the end of that aggregation pipeline, those stages:

{
  $project: {
    mixedDocs: {
      $concatArrays: ['$usersDocs', '$addrDocs'],
    },
  },
},
{
  $unwind: '$mixedDocs',
},
{
  $replaceWith: '$mixedDocs',
},

I am curious, what is the reason, that you want to have an array of mixed objects? :slight_smile: