How to structure python data classes to hold complex yaml data?

Question

I am trying to write python data class(es) to hold data in a yaml config file, using yaml.safe_load() to read-in the data. I'm finding that although I get all the data into my python classes (if I print the data it's all there), I run into problems accessing some of the data from my data class structure, indicating that my class structure is not correct.

Here is an excerpt of the yaml file:

parent_config: ../../../core/base_config.yaml

properties:
  firmware: null
  selenium: true
  device: true
  specs_path: apps/tests
  config_path: apps/batch_tests
  power_supply: # Define power supply to use for test setup
    default_voltage: 4.1

queues:
- name: cloud_default
  properties:
    lib_manager:
      device: true

- name: power_consumption
  properties:
    dut_preparation:
      device: false
    power_supply: # Define power supply to use for test setup
      enabled: true
      type: otii
    multimeter:
      enabled: true
      type: otii

- name: power-thermal-test
  properties:
    dut_preparation:
      device: false
    power_supply: # Define power supply to use for test setup
      enabled: false
    multimeter:
      enabled: true
      type: scope
      serial: ‘00001' # set joulescope serial to use
    thermal:
      enabled: true
      ip_addr: ’00.00.01.1'

- name: build_acceptance
  properties:
    dut_preparation:
      device: true
      dut_requirements:
        queue: 'build_acceptance'

testbeds:
- name: cloud
  queue: cloud_default
  properties: ~

- name: linux
  queue: power_consumption
  properties:
    device_sn: ‘ABCDEF'
    device_id: 110011
    ql:
      enabled: true
      org_id: 112233

- name: 11-mac
  queue: thermal-test
  properties:
    device_sn: ‘XYZSDW'
    device_id: 22222666
    ql:
      enabled: true
      org_id: 227755

- name: cloud
  queue: build_acceptance
  properties: ~

And here is my Python data class structure:

@dataclass
class PowerSupplyClass:
    default_voltage: float

@dataclass
class PropertiesClass:
    firmware: str
    selenium: bool
    device: bool
    specs_path: str
    config_path: str
    power_supply: PowerSupplyClass

@dataclass
class Config:
    parent_config: str
    properties: PropertiesClass
    queues: list
    testbeds: list

Here's my code for loading from YAML file:

import yaml
from test_config2 import Config # This file contains my class structure above
from pprint import pprint


with open("theyaml.yaml", "r") as f:
    config_data = yaml.safe_load(f)

props = Config(**config_data)

pprint(props)
pprint(props.parent_config)
pprint(props.properties)
pprint(props.properties.power_supply.default_voltage) # Here I get an error - AttributeError: 'dict' object has no attribute 'power_supply'
pprint(props.queues)
pprint(props.testbeds)

It seems that I can access elements that are not from nested classes, but when I try to access something that is in a class that's nested underneath another class, I get an error as noted above.

What am I doing wrong?

Also - how will I be able to access any desired element from the "queues" and "testbeds" lists?

I tried various ways of reconfiguring my class structure without success. I need to be able to access any element within the entire structure by simply using the dot operator and the correct sequence of object names, like the "props.properties.power_supply.default_voltage" syntax above.