Q: Is it possible to set mongodb to automatically update a document when a certain condition is met? Is it possible to set mongodb to automatically update a document when a certain condition is met?
Here is my schema:
const ChatRoomSchema = new mongoose.Schema({
  membersOfThisChatRoom: [{
    objectIdOfMember: {
      type: mongoose.Schema.Types.ObjectId,
      ref: 'User',
      required: true,
    },
    joinedOn: {
      type: Date,
      default: Date.now,
      required: true,
    }
  }],
  adminsOfThisChatRoom: {
    type: [{ 
      type: mongoose.Schema.Types.ObjectId,
      ref: 'User',
      required: true,
    }],
  },
});

Is it possible to make it that if the last admin is deleted and there are still users in the chatroom, mongodb/mongoose to automatically set a user(preferably the one who joined the earliest) as an admin? 
Or do I have to do this in the server side logic?
