simplify mongodb pymongo query

Question

I have the following query in pymongo:

query2 = {"$and": [{'eventMetadata.doc.DocId':{"$exists":True}},
                   {'eventMetadata.doc.DocId':{"$not":{"$regex": "-"}}}]
         }

This works. Basically means that the indicated field exists AND that does not contain the regex "-" which basically means that it does not contain "-" I would like to know if there is a better way to check if "-" is not in the desired result without regex and also how could I check that the record is a number.

The following does not work and I dont know why:

query3 = {'eventMetadata.doc.DocId': {"$isNumber":True}} 

--> giving cero results even If I know there are a lot of fields consisting in just in numbers (no alpha characteres)

Answer 1

• To avoid using RegEx, you could resort to $indexOfCP: https://docs.mongodb.com/manual/reference/operator/aggregation/indexOfCP/

• $isNumber doesn't look at the field contents, but at the field type. Hence, in case of string BSON type it will return False. Please refer to this SO for how to select numeric fields only (basically using regex): MongoDB - How to select only numeric strings / Check whether string is numeric in mongo-shell