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Validators Adapter. The common interface for all Python validators.
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VAlidators Adapter makes validation by any existing validator with the same interface.

Supported validators:

validator adapter
Cerberus va.cerberus
Django Forms va.django
Marshmallow va.marshmallow
PySchemes va.pyschemes
Django REST Framework va.restframework
WTForms va.wtforms
python3 -m pip install --user vaa


import marshmallow
import vaa

class Scheme(marshmallow.Schema):
  id = marshmallow.fields.Int(required=True)
  name = marshmallow.fields.Str(required=True)

Validating data

All schemes adopted by va has the same interface:

validator = Scheme({'id': '1', 'name': 'Oleg'})
validator.is_valid()  # True
# {'name': 'Oleg', 'id': 1}

validator = Scheme({'id': 'no', 'name': 'Oleg'})
validator.is_valid()  # False
# {'id': ['Not a valid integer.']}

If error isn't for specific field, iw will be in __all__ key.

Simple scheme

If you want to do validation with simple function, you can use va.simple adapter. For example, you want to check that in dict {'a': ..., 'b': ...} both values are positive. There are many ways to do so.

It can return bool:

def validate(a, b) -> bool:
  return a > 0 and b > 0

Or return message for error:

def validate(a, b) -> bool:
  if a > 0 and b > 0:
    return True
  return 'should be positive'

Or return errors dict:

def validate(a, b) -> bool:
  if a <= 0:
    return {'a': 'should be positive'}
  if b <= 0:
    return {'b': 'should be positive'}
  return True

Or raise va.ValidationError with error message or dict:

def validate(a, b) -> bool:
  if a > 0 and b > 0:
      return True
  raise vaa.ValidationError('should be positive')

Also, if you want to get the original dict without unpacking it into keyword arguments, do a function that accepts only one _ argument:

def validate(_):
  return _['a'] > 0 and _['b'] > 0

In that dict keys can be accessed as attributes:

def validate(_):
  return _.a > 0 and _.b > 0

Choose the best way and follow it. Avoid mixing them in one project.

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