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Pycsi

pycsi is a simple python library to validate data and/or build a validation schema.

Installation

pip install pycsi

Usage

We might begin by creating validation callables such:

def is_divisible_by_three(x: float):
    return x % 3 == 0

def is_all_positive(numbers: list[float]):
    return all(number > 0 for number in numbers)

def is_quotient_positive(x: float, y: float):
    return x / y > 0

Then we can instantiate a Subvalidator instance and the validation callables to it:

from pycsi import Subvalidator

first_subvalidator = Subvalidator(
    "First condition",
    "Number is not divisible by 3",
    is_divisible_by_three,
    x=3
    )

second_subvalidator = Subvalidator(
    "Second condition",
    "Not every number is positive",
    is_all_positive,
    numbers=[1, 2, 3, 4, 5, 6, 7, 8, 9, -10],
    )

third_subvalidator = Subvalidator(
    "Third condition",
    "Quotient is not positive",
    is_quotient_positive,
    x=10,
    y=2,
    )

Finally we can create a validator object and add the subvalidators to it.

from pycsi import Validator

validator = Validator()

validator.add(first_subvalidator)
validator.add(second_subvalidator)
validator.add(third_subvalidator)

validator.run()

The validator will run all the subvalidators and the unvalidated_set property will return a set of the failed subvalidators.

print(validator.unvalidated_set)
{ValidatorError(condition='Second condition', error_message='Not every number is positive')}

Asynchronous Usage

This library also supports async validation. We can create asyncronous validation callables such:

import asyncio

async def async_is_divisible_by_three(x: float) -> bool:
    await asyncio.sleep(0.1)
    return is_divisible_by_three(x)

async def async_is_all_positive(numbers: list[float]) -> bool:
    await asyncio.sleep(0.1)
    return is_all_positive(numbers)

Instead of using the Subvalidator API, we are going to use the AsyncSubvalidator in the next step:

from pycsi import AsyncSubvalidator

first_subvalidator = AsyncSubvalidator(
    "First condition",
    "Number is not divisible by 3",
    async_is_divisible_by_three,
    x=10,
    )

second_subvalidator = AsyncSubvalidator(
    "Second condition",
    "Not every number is positive",
    async_is_all_positive,
    numbers=[1, 2, 3, 4, 5, 6, 7, 8, 9, 10],
    )

Same for the Validator API, we will switch the the AsyncValidator.

from pycsi import AsyncValidator

validator = AsyncValidator()
validator.add(first_subvalidator)
validator.add(second_subvalidator)

await validator.run()
print(validator.unvalidated_set)
{ValidatorError(condition='First condition', error_message='Number is not divisible by 3')}