Yes, that's the purpose of the projection
parameter of find
:
db.collection.find({_id: 1234}, {
'parentfield1.childfield1': 1,
'parentfield1.childfield2': 1,
'parentfield1.childfield3': 1
});
If a specified field isn't present in a given doc, the other matching fields will still be included.
Build up the projection
parameter object programmatically if you want it to be dynamic.