This package provides a set of tools that helps with validation of input data.

To get the package on your system, type

$ pip install vutils-validator

Please, read the following subsections to get more info about particular use case.

Module vutils.validator.basic provides a set of functions for validation of simple input data forms, like email addresses:

• verify_not_empty(value) fails if value is empty.
• verify_matches(value, regex, message="") fails if value does not match regular expression regex. Since many regular expressions describe entities that have a name (identifier, number, email address, etc.) the default error message can be overridden by message argument.
• verify_email(value) fails if value is not an email address (currently described by simple ^\S+@\S+\.[A-Za-z]+$ regular expression).

The value passed to all validation functions can be either str or a ValueHolder (from vutils.validator.value) object. A ValueHolder object can be used to store additional information about value, like its name and origin. The synopsis of ValueHolder's constructor is __init__(self, value, name="The value", location=None), where value, name, and location are value, its name, and the location of its origin, respectively. location is a Location (from vutils.validator.value) object that holds path, line, and column of the value/token origin. ValueHolder serves to provide more detail about value in error messages issued by validation functions by raising ValidationError (from vutils.validator.errors) when the validation fails, example:

from vutils.validator.basic import verify_email
from vutils.validator.errors import ValidationError
from vutils.validator.value import ValueHolder


def get_input(name):
    return ValueHolder(input(f"Enter {name}: "), name)


try:
    verify_email(get_input("email"))
except ValidationError as exc:
    print(exc)

On ill-formed input, the example prints email must be an email address!, since get_input names a value as email.

Module vutils.validator.schema provides function validate(data, schema) for data validation against JSON schema schema. Function returns None in case of valid data or list of jsonschema.exceptions.{Validation,Schema}Error in case of invalid data or schema.