MongoDB how to find any value in case nothing is set in parameters?

Question

MongoDB

Good day!
Tell me how to find any value if the parameters are empty? In this case, the structure of the request must be preserved.

db.ad.find({"electronics.categoryId" : 1}).count(); //все ок
db.ad.find({"electronics.categoryId" : ????????? }).count(); //показать все, если в параметрах пусто

Answer 1

?

db.ad.find({"electronics.categoryId": { $exists: false } }).count();