JSON validation framework for Python.
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README.rst

incoming: JSON validation framework for Python

incoming is a JSON validation framework.

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Overview

Validating anything can get really messy. JSON being one of the most used formats for data exchange, incoming aims at solving the problem of validating JSON with structure and ease.

incoming is a small framework for validating JSON. It's up to you where and how to use it. A common use-case (and the primary reason why I wrote this framework) is validating incoming JSON when writing HTTP servers.

Features

  • Classes that can be sub-classed for writing structured validators.
  • Basic validators (or datatypes) for performing common validations, like string, numbers, booleans, lists, nested JSON, etc.
  • Allows extending validators (datatypes) to write your own.
  • Allows writing callables for validating values.
  • Captures errors during validation and returns a complete report of errors.
  • Allows reporting different errors for different validation test failures for the same value.

Installation

Installation is simple.

pip install incoming

Basic Usage

import json

from datetime import date
from incoming import datatypes, PayloadValidator


class MovieValidator(PayloadValidator):
    name = datatypes.String()
    rating = datatypes.Function(
        'validate_rating',
        error='Rating must be in between 1 and 10.',
    )
    actors = datatypes.Array()
    is_3d = datatypes.Boolean()
    release_year = datatypes.Function(
        'validate_release_year',
        error='Release year must be in between 1800 and current year.',
    )

    # validation method can be a regular method
    def validate_rating(self, val, *args, **kwargs):
        return isinstance(val, int) and val >= 1 and val <= 10

    # validation method can be a staticmethod as well
    @staticmethod
    def validate_release_year(val, *args, **kwargs):
        return all((
            isinstance(val, int),
            val >= 1800,
            val <= date.today().year,
        ))

payload = {
    'name': 'Avengers',
    'rating': 5,
    'actors': [
        'Robert Downey Jr.',
        'Samuel L. Jackson',
        'Scarlett Johansson',
        'Mark Ruffalo'
    ],
    'is_3d': True,
    'release_year': 2012
}
result, errors = MovieValidator().validate(payload)
assert result and errors is None, 'Validation failed.\n%s' % json.dumps(errors, indent=2)

payload = {
    'name': 'Avengers',
    'rating': 11,
    'actors': [
        'Robert Downey Jr.',
        'Samuel L. Jackson',
        'Scarlett Johansson',
        'Mark Ruffalo'
    ],
    'is_3d': 'True',
    'release_year': 9000
}
result, errors = MovieValidator().validate(payload)
assert result and errors is None, 'Validation failed.\n%s' % json.dumps(errors, indent=2)

If you run the above script, you will get:

Traceback (most recent call last):
  File "code.py", line 67, in <module>
    assert result and errors is None, 'Validation failed.\n%s' % json.dumps(errors, indent=2)
AssertionError: Validation failed.
{
  "rating": [
    "Rating must be in between 1 and 10."
  ],
  "is_3d": [
    "Invalid data. Expected a boolean value."
  ],
  "release_year": [
    "Release year must be in between 1800 and current year."
  ]
}

Documentation

Documentation is available on Read The Docs.

Tests

Simply run:

python setup.py test

or:

py.test incoming

Contributors

Licence

See LICENCE.