Install

pip3 install pythonish-validator

Error messages

from pythonish_validator.common import validate

validator = validate({
    'name': str,
    'age': int,
    'skills': [str]
}, {
    'name': 'Georgy',
    'age': None,
    'skills': ['Python', 'Perl', 42]
})

assert validator.repr_errors() == [
    "{'age'}->NoneType(None)",
    "{'skills'}->[2]->int(42)"
]

Basic typing module support

Supported types: List, Dict, Optional, Union.

from typing import Dict, List, Optional, Union
from pythonish_validator.common import validate

schema_example = {
    'name': str,
    'age': Optional[int],  # None if undefined
    'skill': Union[str, List[str]],  # Awful API, but who cares...
    'level_by_skill': Dict[str, str]
}

valid_data = {
    'name': 'Georgy',
    'age': None,
    'skill': ['Python', 'ECMA Script'],
    'level_by_skill': {
        'Python': 'senior',
        'ECMA Script': 'middle',
    }
}

validator = validate(schema_example, valid_example)

Features

🗣️ Speak the language of Python classes:

from pythonish_validator.common import Validator


class User:
    __validation_schema__ = {
        'id': int,
        'name': str
    }


validator = Validator({
    "users": [User]
})

# valid structure
validator.is_valid({
    "users": [
        {'id': 1, 'name': 'Alice'},
        {'id': 2, 'name': 'Bob'},
    ]
})

# invalid structure
validator.is_valid({
    "users": [
        {'id': '1', 'name': 'Alice'},
        {'id': 2},
    ]
})

assert validator.repr_errors() == [
    "{'users'}->[0]->{'id'}->str('1')",
    "{'users'}->[1]->{'name'}",
]

🎓 And even custom validation:

import re

from pythonish_validator.common import Validator


class EmailType:
    @staticmethod
    def __validation_schema__(data):
        if not isinstance(data, str):
            return False

        if re.match(r'^\w+@\w+.\w{2,5}$', data) is None:
            return False

        return True


class User:
    __validation_schema__ = {
        'id': int,
        'name': str,
        'email': EmailType,
    }


validator = Validator({
    "users": [User]
})

validator.is_valid({
    "users": [
        {'id': 1, 'name': 'Alice', 'email': 'alice@example.com'},
        {'id': 2, 'name': 'Bob', 'email': 'bob@example.com'},
    ]
})

If you find any mistake – please write to the issue list 🐨 (https://github.com/bugov/pythonish-validator/issues).