Doolally

Doolally is a JSON sanity checker and json-schema generator. It has a strong focus on good, readable, descriptive errors. (If your JSON isn't sane, then you'll go doolally!, Geddit!?)

A trivial example:

from doolally import (
    Schema,
    String,
    Number,
    validate,
    jsonschema,
    ValidationValueError,
)

class Person(Schema):
    jsonschema_description = "A Person instance"

    name = String(required=True, description="Full name of Person")
    age = Number(required=True, is_int=True, signed=False,
                 description="How old the person is")

# This will pass just fine
validate({"name": "John", "age": 34}, Person)

# And this will raise an exception
try:
    validate({"wrongKey": "John"}, Person)
except ValidationValueError as exc:
    print(exc)

# A newline + jsonschema
from pprint import pprint
print()
print(pprint(jsonschema(Person)))

Output:

[:Person(name(required,String()), age(required,Number(unsigned,int)))] - unrecognised key (wrongKey)

{'additionalProperties': False,
 'description': 'A Person instance',
 'properties': {'age': {'description': 'How old the person is',
                        'minimum': 0,
                        'title': 'age',
                        'type': 'integer'},
                'name': {'description': 'Full name of Person',
                         'title': 'name',
                         'type': 'string'}},
 'required': ['name', 'age'],
 'title': 'Person',
 'type': 'object'}

Project Goals:

* Zero-copy JSON sanity checker 
* Strong error reporting including path/expected type etc.
* Context depdendent sanity checking via collection validators
* API to generate doolally classes at Runtime
* Generate json-schema documents

Project Non-Goals:

* Python Object (de)serializer
* Allow for collection modification

1. Installation

Installation

To install doolally simply copy and paste doolally.py. This project is too small/new to be worth packaging. There are currently no third party dependencies in doolally.

Testing

To run the test suite pytest is required. First clone this repo before running the following command.

    $ pytest --doctest-modules -v .