PyCont

Validate and genereate pythpon objects from templates. Library is powered by Trafaret and helps to validate and genereate data from template.

Documentation

https://pycont.readthedocs.io/en/latest/index.html

Usage

pip install pycont

Simple data template

>>> from pycont import Template, Contract
>>> import trafaret as t
>>> contract = Contract(Template(t.Int()))
>>> print(contract(42))
42
>>> print(contract('test'))
Traceback (most recent call last):
  ...
ValueError: Invalid value: value can't be converted to int

Simple list template

>>> from pycont import Template, Contract
>>> import trafaret as t
>>> contract = Contract([
...  Template(t.Int())
...])
>>> print(contract([42]))
[42]
>>> print(contract([1, 2, 3, 4, 5]))
[1, 2, 3, 4, 5]
>>> print(contract([1, 2, 3, 'error']))
Traceback (most recent call last):
  ...
ValueError: Invalid value: value can't be converted to int

Static list template

>>> from pycont import Template, Contract
>>> import trafaret as t
>>> contract = Contract([
...  Template(t.Int()),
...  Template(t.String()),
...  Template(t.Float()),
...])
>>> print(contract([42, 'test', 12.5]))
[42, 'test', 12.5]

Dict template

>>> from pycont import Template, Contract
>>> import trafaret as t

>>> contract = Contract(Template(t.Int(), default=42))
>>> print(contract('error'))
42

>>> contract = Contract({
...  'id': Template(t.Int()),
...  'value': Template(t.String()),
...})
# Key 'key' not contains in template
>>> print(contract({'id': 1, 'value': 'test', 'key': None}))
{'id': 1, 'value': 'test'}

Deafult value

pycont.Template contains an optional argument default (the default type must be valid to Tremplate checker). If the argument is set, then if the check fails, this value will be returned.

>>> from pycont import Template, Contract
>>> import trafaret as t

>>> contract = Contract({
...  'id': Template(t.Int()),
...  'value': Template(t.String(), default='None'),  # 'None' is a string
...})
>>> print(contract({'id': 1, 'key': None}))  # key 'value' is not set
{'id': 1, 'value': 'None'}