Check for missing field or null value in mongoDB atlas

Hi @Jason_Tran I have already put the requirements in the question. Please go through the question again.
I will put requirements again :
My goal is to get all documents:

  1. use $search as i am using atlas and not mongodb
  2. expiryDate doesn’t exists OR
  3. If expiryDate does exists, then it must be null OR
  4. If expiryDate does exists, then it must greater than current time.