The $ push operator in mongoDB accepts only numeric value to change when I try to do sub = 1 , for example, it does not work. In the first example I can update normally (static), in the second not.
db.my_collection.updateOne({"_id":3, "p_act": 2},{$push:{"p_act.$.subact.**3**.annotations":{"an_description":"bla bla bla","an_date":new Date()}}})
sub = 3
db.my_collection.updateOne({"_id":3, "p_act": 2},{$push:{"p_act.$.subact.**sub**.annotations":{"an_description":"bla bla bla","an_date":new Date()}}})
What am I doing wrong? Is there any other way to do it?