Best way to find all documents with 2 fields in mongoDb-CodePudding

i need help in finding documents in mongodb. My schema is like below:

const users = new Schema({
      _id: ObjectId,
      facebookId: String,
      .....
      .....
})

I have 2 arrays for query like below:

const facebookIds = ['1', '2', '3']
const _ids = ['1', '2', '3']

At the moment, I am thinking of finding all the documents with facebookIds array first, getting their _id, concat the result with _ids array, and finally finding all the documents with resultant _ids array.

So, I want to know that what will be the best way to query the documents in one go, or this is the only way.

Thanks in advance.

CodePudding user response：

Assuming you have 3 users in the collection with facebookId and another 3 without facebookId. You already have the facebookId of the first 3 data and _id of the last 3 data.

    [
  {
    _id: 1,
      facebookId: 10,
  },
  {
    _id: 2,
      facebookId: 20,
  },
  {
    _id: 3,
      facebookId: 10,
  },
  {
    _id: 4,
      facebookId: null,
  },
  {
    _id: 5,
      facebookId: null,
  },
  {
    _id: 6,
      facebookId: null,
  }
]

You can use $or operator and $in operator for this

db.collection.find({
  $or: [
    {
      facebookId: {
        $in: [10,20,30]
      }
    },
    {
      _id: {
        $in: [4,5,6]
      }
    }
  ]
})

Here is a working mongoplayground link