Reading YAML config file in python and using variables

Question

Say I have a yaml config file such as:

test1:
    minVolt: -1
    maxVolt: 1
test2:
    curr: 5
    volt: 5

I can read the file into python using:

import yaml

with open("config.yaml", "r") as f:
    config = yaml.load(f)

Then I can access the variables with

config['test1']['minVolt']

Style-wise, what is the best way to use variables from the config file? I will be using the variables in multiple modules. If I simply access the variables as shown above, if something is renamed, I will need to rename every instance of the variable.

Just wondering what the best or common practices for using variables from a config file in different modules.

Answer 1

You can do this:

class Test1Class:
    def __init__(self, raw):
        self.minVolt = raw['minVolt']
        self.maxVolt = raw['maxVolt']

class Test2Class:
    def __init__(self, raw):
        self.curr = raw['curr']
        self.volt = raw['volt']

class Config:
    def __init__(self, raw):
        self.test1 = Test1Class(raw['test1'])
        self.test2 = Test2Class(raw['test2'])

config = Config(yaml.safe_load("""
test1:
    minVolt: -1
    maxVolt: 1
test2:
    curr: 5
    volt: 5
"""))

And then access your values with:

config.test1.minVolt

When you rename the values in the YAML file, you only need to change the classes at one place.

Note: PyYaml also allows you to directly deserialize YAML to custom classes. However, for that to work, you'd need to add tags to your YAML file so that PyYaml knows which classes to deserialize to. I expect that you do not want to make your YAML input more complex.

Answer 2

See Munch , Load YAML as nested objects instead of dictionary in Python

import yaml
from munch import munchify
c = munchify(f)yaml.safe_load(…))
print(c.test1.minVolt)
# -1
# Or
f = open(…)
c = Munch.fromYAML(f)