I have 3 collections(User, Credit and Status). Every User have 1 Credit data and Many Status Data like this:

Users Document

[
  {
  "_id": ObjectId("123"),
  "Name": "First User"
  },
  {
  "_id": ObjectId("1234"),
  "Name": "Second User"
  },
  {
  "_id": ObjectId("12345"),
  "Name": "Third User"
  }
]

Credit Document

[
  {
  "_id": ObjectId("456"),
  "userId": ObjectId("123"),
  "credit": 100
  },
  {
  "_id": ObjectId("456"),
  "userId": ObjectId("1234"),
  "credit": 10
  },
  {
  "_id": ObjectId("456"),
  "userId": ObjectId("12345"),
  "credit": 100
  }
]

Status Document

[
  {
    "_id": ObjectId("111"),
    "userId": ObjectId("123"),
    "status": "First User Status",
    "useCredit": 1
  },
  {
    "_id": ObjectId("222"),
    "userId": ObjectId("1234"),
    "status": "Second User Status",
    "useCredit": 20
  },
  {
    "_id": ObjectId("222"),
    "userId": ObjectId("1234"),
    "status": "Second User Status",
    "useCredit": 10
  },
  {
    "_id": ObjectId("333"),
    "userId": ObjectId("12345"),
    "status": "Third User Status",
    "useCredit": 3
  },
  {
    "_id": ObjectId("444"),
    "userId": ObjectId("12345"),
    "status": "Third User Status",
    "useCredit": 4
  },
  {
    "_id": ObjectId("555"),
    "userId": ObjectId("12345"),
    "status": "Third User Status",
    "useCredit": 2
  },
  {
    "_id": ObjectId("666"),
    "userId": ObjectId("12345"),
    "status": "Third User Status",
    "useCredit": 2
  }
]

I want to get random Status with:

1. userId of Status not equal with User “_id”
2. User Credit equal or greater than useCredit of Status

Example:

If First User do query, he will get one random data from Status Document except “_id: 111″(because own status) and “_id: 222” (because, credit not enough).

I am thinking using aggregate but I don’t figure out how to do it..