How to validate structure (or schema) of dictionary in Python?

Question

I have a dictionary with config info:

my_conf = {
    'version': 1,

    'info': {
        'conf_one': 2.5,
        'conf_two': 'foo',
        'conf_three': False,
        'optional_conf': 'bar'
    }
}

I want to check if the dictionary follows the structure I need.

I'm looking for something like this:

conf_structure = {
    'version': int,

    'info': {
        'conf_one': float,
        'conf_two': str,
        'conf_three': bool
    }
}

is_ok = check_structure(conf_structure, my_conf)

Is there any solution done to this problem or any library that could make implementing check_structure more easy?

Answer 1

You may use schema (PyPi Link)

schema is a library for validating Python data structures, such as those obtained from config-files, forms, external services or command-line parsing, converted from JSON/YAML (or something else) to Python data-types.

from schema import Schema, And, Use, Optional, SchemaError

def check(conf_schema, conf):
    try:
        conf_schema.validate(conf)
        return True
    except SchemaError:
        return False

conf_schema = Schema({
    'version': And(Use(int)),
    'info': {
        'conf_one': And(Use(float)),
        'conf_two': And(Use(str)),
        'conf_three': And(Use(bool)),
        Optional('optional_conf'): And(Use(str))
    }
})

conf = {
    'version': 1,
    'info': {
        'conf_one': 2.5,
        'conf_two': 'foo',
        'conf_three': False,
        'optional_conf': 'bar'
    }
}

print(check(conf_schema, conf))