jsch
Define classes that conform to a JSON schema, with built-in validation and schema generation.
Creating a schema object
A Schema object represents a validated JSON schema. Any recognised
JSON schema field can be passed as a keyword argument when initialising a
Schema object:
>>> from jsch.schema import Schema
>>>
>>> Schema()
<jsch.schema.Schema object at 0x...>
>>>
>>> schema = Schema(title='First name', type='string', max_length=32)
>>> schema.max_length
32
>>> schema.title
'First name'
>>>Keywords are provided in the underscored format rather than the camel case
format used by the JSON schema definition, i.e. max_length rather than
maxLength. This is done to conform to the PEP8 Style Guide.
A SchemaValidationError will be raised on initialisation if any
JSON schema validation rules are breached:
>>> from jsch.schema import Schema
>>>
>>> Schema(title='Luggage', type='array', max_items=0.5)
Traceback (most recent call last):
...
jsch.schema.SchemaValidationError: 'max_items' must be an int
>>>
>>> Schema(title='Height', type='object', required=[])
Traceback (most recent call last):
...
jsch.schema.SchemaValidationError: 'required' list must not be empty
>>>The schema validation rules in the JSON schema specification go a long way
towards ensuring a schema is valid, but there are still some gaps, especially
around inter-keyword validation. For more strict validation when creating a
schema object, use the SchemaStrict class instead:
>>> # not yet implemented
>>> Accessing the JSON schema
The JSON schema can be accessed as either a dict or a JSON string:
>>> from jsch.schema import Schema
>>>
>>> schema = Schema(
... title='Approximate Age',
... type='integer',
... minimum=0,
... multiple_of=10
... )
>>>
>>> dict = schema.asdict()
>>> import pprint
>>> pprint.pprint(dict)
{'minimum': 0, 'multipleOf': 10, 'title': 'Approximate Age', 'type': 'integer'}
>>>
>>> json = schema.asjson()
>>> print(json)
{"minimum":0,"multipleOf":10,"title":"Approximate Age","type":"integer"}
>>>
>>> pretty_json = schema.asjson(pretty=True)
>>> print(pretty_json)
{
"minimum": 0,
"multipleOf": 10,
"title": "Approximate Age",
"type": "integer"
}
>>>If the schema is intended to be a root schema, specify the root flag with an
optional $schema string when converting to a dict or a JSON string:
>>> from jsch.schema import Schema
>>>
>>> schema = Schema(title='Height', type='number')
>>>
>>> json = schema.asjson(pretty=True, root=True)
>>> print(json)
{
"$schema": "http://json-schema.org/draft-04/schema#",
"title": "Height",
"type": "number"
}
>>>
>>> dict = schema.asdict(root=True, schema='http://jsch.org/custom-schema#')
>>> import pprint
>>> pprint.pprint(dict)
{'$schema': 'http://jsch.org/custom-schema#',
'title': 'Height',
'type': 'number'}
>>>Simplifying schema object creation
For convenience, a class is provided for each of the primitive JSON schema
types, to save specifying the type keyword:
>>> from jsch.schema import Array, Integer, String
>>>
>>> schema = String(pattern='^[0-9]{4}$')
>>> json = schema.asjson(pretty=True)
>>> print(json)
{
"pattern": "^[0-9]{4}$",
"type": "string"
}
>>>
>>> schema = Array(items=Integer(), min_items=1)
>>> json = schema.asjson(pretty=True)
>>> print(json)
{
"items": {
"type": "integer"
},
"minItems": 1,
"type": "array"
}
>>>
