is it possible to use wildcards for field names in mongodb?

Question

I have a set of field names as follows:

"field0.registers.hilo"
"field0.registers.lllo"
...

"field1.registers.hilo"
"field1.registers.lllo"
...

"field2.registers.hilo"
"field2.registers.lllo"
...


"fieldn.registers.hilo"
"fieldn.registers.lllo"
...

Is there a way to indicate the fields in mongodb with the index to range from 0 to n succinctly without having to expand it all out beforehand?

something like this example for project:

{ $project: { "fieldn.registers.hilo": 1, "fieldn.registers.lllo": 1 } }

For now, I am fully expanding all the project fields from 0 to n in python before interfacing with the collection using pymongo.

Answer 1

is it possible to use wildcards for field names in mongodb?

No.

If your data is in this structure, refactor it to use lists. That's exactly what lists are desgined for.

Taking the refactored example below, Use $elemMatch to project only the array elements needed:

from pymongo import MongoClient

db = MongoClient()['mydatabase']

db.register.insert_many([{
    'registers': [
        {
            'field': 0,
            'hilo': 1,
            'lllo': 2
        },
        {
            'field': 1,
            'hilo': 2,
            'lllo': 3
        },
        {
            'field': 2,
            'hilo': 3,
            'lllo': 4
        }
    ]}])

print(db.register.find_one({}, {'registers': {'$elemMatch': {'field': 1}}}))

prints:

{'_id': ObjectId('60b64e57c3214d73c390557b'), 'registers': [{'field': 1, 'hilo': 2, 'lllo': 3}]}