validpeas

Small library to create structured validations.

Define validations in a structured way, so the result is also structured and easy to understand what went wrong.

While functional, still has a lot of room for improvement. No breaking changes will be introduced in the 0.x.x versions.

Example

The example is a simple JSON validation. The JSON should have a field called "numbers" that is a list of integers. The list should have at least 6 elements and be in ascending order.

Just for the sake of the example, the validation is done in a very verbose way, with a lot of intermediate steps, so the result is also verbose and easy to understand.

Validation definition

from json import loads
from typing import Any
from itertools import pairwise

from validpeas import (
    ValidationResult,
    make_composite_processor,
    make_validator,
    processor_from_validator,
    human_text_result_report,
)


# ##################### Elemental validators ######################
# These validators are the basic building blocks, the ones that
# actually do the validation.


@processor_from_validator
@make_validator()
def is_string(data: Any) -> bool:
    return isinstance(data, str)


@processor_from_validator
@make_validator()
def is_valid_json(json_string: str) -> bool:
    try:
        loads(json_string)
        return True
    except ValueError:
        return False


@processor_from_validator
@make_validator()
def has_numbers_field(data: dict) -> bool:
    return "numbers" in data


@processor_from_validator
@make_validator()
def is_list(data: Any) -> bool:
    return isinstance(data, list)


@processor_from_validator
@make_validator()
def is_integer(data: Any) -> bool:
    return isinstance(data, int)


@processor_from_validator
@make_validator()
def length_is_greater_than_5(data: list) -> bool:
    return len(data) > 5


@processor_from_validator
@make_validator()
def ascending_pair(numbers: tuple[int, int]) -> bool:
    return numbers[0] < numbers[1]


# ####################### Composite validators ########################
# These validators are composed of elemental validators, they provide
# structure to the validations in a logical way, and also dispatch
# and process the data for the elemental validators.


@make_composite_processor()
def all_list_items_are_integers(numbers: list[Any]) -> list[ValidationResult]:
    return list(map(is_integer, numbers))


@make_composite_processor()
def is_in_ascending_order(numbers: list[int]) -> list[ValidationResult]:
    return list(map(ascending_pair, pairwise(numbers)))


# Define a custom name for the main validator
@make_composite_processor("JSON with +6 numbers in ascending order")
def main_validator(data: Any) -> list[ValidationResult]:
    is_string_result = is_string(data)

    is_valid_json_result = is_valid_json(data, dependencies=[is_string_result])

    json_data = loads(data) if is_valid_json_result.passed else None

    has_numbers_field_result = has_numbers_field(
        json_data, dependencies=[is_valid_json_result]
    )

    numbers = json_data["numbers"] if has_numbers_field_result.passed else None

    is_list_result = is_list(numbers, dependencies=[has_numbers_field_result])

    length_is_greater_than_5_result = length_is_greater_than_5(
        numbers, dependencies=[is_list_result]
    )
    all_list_items_are_integers_result = all_list_items_are_integers(
        numbers, dependencies=[is_list_result]
    )

    is_in_ascending_order_result = is_in_ascending_order(
        numbers, dependencies=[all_list_items_are_integers_result]
    )

    return [
        is_string_result,
        is_valid_json_result,
        has_numbers_field_result,
        is_list_result,
        length_is_greater_than_5_result,
        all_list_items_are_integers_result,
        is_in_ascending_order_result,
    ]


# ####################### Run validations ########################
# Run the main validator with different samples of data and print


samples = [
    5,
    "gfdgsgfsggfds",
    '{"asdf": [1, 2, 3, 5, 4]}',
    '{"numbers": [1, 2, 3]}',
    '{"numbers": [1, 2, 3, 4, 5, "a"]}',
    '{"numbers": [1, 2, 3, "b"]}',
    '{"numbers": [1, 2, 3, 4, 6, 5, 7, 8, 9, 10]}',
    '{"numbers": [1, 2, 3, 4, 5, 6]}',
]

result_separator = "\n--------------------------------------------------\n\n"

result_reports = (
    (f"INPUT: {sample}\n\n" f"{human_text_result_report(main_validator(sample))}")
    for sample in samples
)

print(result_separator.join(result_reports))

Output

INPUT: 5

❌ JSON with +6 numbers in ascending order
    ❌ is_string
    ⚠️ is_valid_json
    ⚠️ has_numbers_field
    ⚠️ is_list
    ⚠️ length_is_greater_than_5
    ⚠️ all_list_items_are_integers
    ⚠️ is_in_ascending_order

--------------------------------------------------

INPUT: gfdgsgfsggfds

❌ JSON with +6 numbers in ascending order
    ✅ is_string
    ❌ is_valid_json
    ⚠️ has_numbers_field
    ⚠️ is_list
    ⚠️ length_is_greater_than_5
    ⚠️ all_list_items_are_integers
    ⚠️ is_in_ascending_order

--------------------------------------------------

INPUT: {"asdf": [1, 2, 3, 5, 4]}

❌ JSON with +6 numbers in ascending order
    ✅ is_string
    ✅ is_valid_json
    ❌ has_numbers_field
    ⚠️ is_list
    ⚠️ length_is_greater_than_5
    ⚠️ all_list_items_are_integers
    ⚠️ is_in_ascending_order

--------------------------------------------------

INPUT: {"numbers": [1, 2, 3]}

❌ JSON with +6 numbers in ascending order
    ✅ is_string
    ✅ is_valid_json
    ✅ has_numbers_field
    ✅ is_list
    ❌ length_is_greater_than_5
    ✅ all_list_items_are_integers
        ✅ is_integer
        ✅ is_integer
        ✅ is_integer
    ✅ is_in_ascending_order
        ✅ ascending_pair
        ✅ ascending_pair

--------------------------------------------------

INPUT: {"numbers": [1, 2, 3, 4, 5, "a"]}

❌ JSON with +6 numbers in ascending order
    ✅ is_string
    ✅ is_valid_json
    ✅ has_numbers_field
    ✅ is_list
    ✅ length_is_greater_than_5
    ❌ all_list_items_are_integers
        ✅ is_integer
        ✅ is_integer
        ✅ is_integer
        ✅ is_integer
        ✅ is_integer
        ❌ is_integer
    ⚠️ is_in_ascending_order

--------------------------------------------------

INPUT: {"numbers": [1, 2, 3, "b"]}

❌ JSON with +6 numbers in ascending order
    ✅ is_string
    ✅ is_valid_json
    ✅ has_numbers_field
    ✅ is_list
    ❌ length_is_greater_than_5
    ❌ all_list_items_are_integers
        ✅ is_integer
        ✅ is_integer
        ✅ is_integer
        ❌ is_integer
    ⚠️ is_in_ascending_order

--------------------------------------------------

INPUT: {"numbers": [1, 2, 3, 4, 6, 5, 7, 8, 9, 10]}

❌ JSON with +6 numbers in ascending order
    ✅ is_string
    ✅ is_valid_json
    ✅ has_numbers_field
    ✅ is_list
    ✅ length_is_greater_than_5
    ✅ all_list_items_are_integers
        ✅ is_integer
        ✅ is_integer
        ✅ is_integer
        ✅ is_integer
        ✅ is_integer
        ✅ is_integer
        ✅ is_integer
        ✅ is_integer
        ✅ is_integer
        ✅ is_integer
    ❌ is_in_ascending_order
        ✅ ascending_pair
        ✅ ascending_pair
        ✅ ascending_pair
        ✅ ascending_pair
        ❌ ascending_pair
        ✅ ascending_pair
        ✅ ascending_pair
        ✅ ascending_pair
        ✅ ascending_pair

--------------------------------------------------

INPUT: {"numbers": [1, 2, 3, 4, 5, 6]}

✅ JSON with +6 numbers in ascending order
    ✅ is_string
    ✅ is_valid_json
    ✅ has_numbers_field
    ✅ is_list
    ✅ length_is_greater_than_5
    ✅ all_list_items_are_integers
        ✅ is_integer
        ✅ is_integer
        ✅ is_integer
        ✅ is_integer
        ✅ is_integer
        ✅ is_integer
    ✅ is_in_ascending_order
        ✅ ascending_pair
        ✅ ascending_pair
        ✅ ascending_pair
        ✅ ascending_pair
        ✅ ascending_pair