How to convert primitive array into object array with key and value?

Working with Data
, ,
4

Here is the query for that.

db.collection.aggregate([ 
{ 
  $unwind: "$array" 
}, 
{ 
  $group: { 
      _id: { _id: "$_id", a: "$a" }, 
      count: { $sum: 1 } 
  } 
},
{ 
  $sort: { _id: 1 }
},
{ 
  $group: { 
      _id: "$_id._id", 
      array: { $push: { item: "$_id.array", repeated: "$count" }} 
  }
} 
])
2 Likes