Mongodb - Group and count

Question

Below is my mongodb structure

 [
  {
    "_id": "com.android.angrybirds",
    "rating": [
      {
        "user": "BBE74610BEE1A92784FDB",
        "value": "1"
      },
      {
        "user": "BBE74610BEE1A92784F",
        "value": "5"
      },
      {
        "user": "BBE74610BEE1A9784F",
        "value": "5"
      }
    ]
  }
]

I want to group and count the unique ratings. I tried to use aggregate, group but it didn't work.

Expected output

[
  {
    "_id": "com.avatarrom.angrybirds",
    "rating": [
      {
        "1": 1,
        "5": 2
      }
    ]
  }
]

Answer 1

Like @RickyA said, your aggregation query would be interesting. What you need is the aggregate function in combination with the group operator. This post has a nice sample how you can do that.