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"""
Validators for applying validations in sequence.
"""
from __future__ import absolute_import
from .api import (FancyValidator, Identity, Invalid, NoDefault, Validator,
is_validator)
import six
__all__ = ['CompoundValidator', 'Any', 'All', 'Pipe']
############################################################
## Compound Validators
############################################################
def to_python(validator, value, state):
return validator.to_python(value, state)
def from_python(validator, value, state):
return validator.from_python(value, state)
class CompoundValidator(FancyValidator):
"""Base class for all compound validators."""
if_invalid = NoDefault
accept_iterator = False
validators = []
__unpackargs__ = ('*', 'validatorArgs')
__mutableattributes__ = ('validators',)
_deprecated_methods = (
('attempt_convert', '_attempt_convert'),)
@staticmethod
def __classinit__(cls, new_attrs):
FancyValidator.__classinit__(cls, new_attrs)
toAdd = []
for name, value in six.iteritems(new_attrs):
if is_validator(value) and value is not Identity:
toAdd.append((name, value))
# @@: Should we really delete too?
delattr(cls, name)
toAdd.sort()
cls.validators.extend([value for _name, value in toAdd])
def __init__(self, *args, **kw):
Validator.__init__(self, *args, **kw)
self.validators = self.validators[:]
self.validators.extend(self.validatorArgs)
@staticmethod
def _repr_vars(names):
return [n for n in Validator._repr_vars(names)
if n != 'validatorArgs']
def _attempt_convert(self, value, state, convertFunc):
raise NotImplementedError("Subclasses must implement _attempt_convert")
def _convert_to_python(self, value, state=None):
return self._attempt_convert(value, state,
to_python)
def _convert_from_python(self, value, state=None):
return self._attempt_convert(value, state,
from_python)
def subvalidators(self):
return self.validators
class Any(CompoundValidator):
"""Check if any of the specified validators is valid.
This class is like an 'or' operator for validators. The first
validator/converter in the order of evaluation that validates the value
will be used.
The order of evaluation differs depending on if you are validating to
Python or from Python as follows:
The validators are evaluated right to left when validating to Python.
The validators are evaluated left to right when validating from Python.
Examples::
>>> from formencode.validators import DictConverter
>>> av = Any(validators=[DictConverter({2: 1}),
... DictConverter({3: 2}), DictConverter({4: 3})])
>>> av.to_python(3)
2
>>> av.from_python(2)
3
"""
def _attempt_convert(self, value, state, validate):
lastException = None
validators = self.validators
if validate is to_python:
validators = reversed(validators)
for validator in validators:
try:
return validate(validator, value, state)
except Invalid as e:
lastException = e
if self.if_invalid is NoDefault:
raise lastException
return self.if_invalid
@property
def not_empty(self):
not_empty = True
for validator in self.validators:
not_empty = not_empty and getattr(validator, 'not_empty', False)
return not_empty
def is_empty(self, value):
# sub-validators should handle emptiness.
return False
@property
def accept_iterator(self):
accept_iterator = False
for validator in self.validators:
accept_iterator = accept_iterator or getattr(
validator, 'accept_iterator', False)
return accept_iterator
class All(CompoundValidator):
"""Check if all of the specified validators are valid.
This class is like an 'and' operator for validators. All
validators must work, and the results are passed in turn through
all validators for conversion in the order of evaluation. All
is the same as `Pipe` but operates in the reverse order.
The order of evaluation differs depending on if you are validating to
Python or from Python as follows:
The validators are evaluated right to left when validating to Python.
The validators are evaluated left to right when validating from Python.
`Pipe` is more intuitive when predominantly validating to Python.
Examples::
>>> from formencode.validators import DictConverter
>>> av = All(validators=[DictConverter({2: 1}),
... DictConverter({3: 2}), DictConverter({4: 3})])
>>> av.to_python(4)
1
>>> av.from_python(1)
4
"""
def __repr__(self):
return '<All %s>' % self.validators
def _attempt_convert(self, value, state, validate):
# To preserve the order of the transformations, we do them
# differently when we are converting to and from Python.
validators = self.validators
if validate is to_python:
validators = reversed(validators)
try:
for validator in validators:
value = validate(validator, value, state)
except Invalid:
if self.if_invalid is NoDefault:
raise
return self.if_invalid
return value
def with_validator(self, validator):
"""Add another validator.
Adds the validator (or list of validators) to a copy of
this validator.
"""
new = self.validators[:]
if isinstance(validator, (list, tuple)):
new.extend(validator)
else:
new.append(validator)
return self.__class__(*new, **dict(if_invalid=self.if_invalid))
@classmethod
def join(cls, *validators):
"""Join the specified validators.
Joins several validators together as a single validator,
filtering out None and trying to keep `All` validators from
being nested (which isn't needed).
"""
validators = [v for v in validators if v and v is not Identity]
if not validators:
return Identity
if len(validators) == 1:
return validators[0]
if isinstance(validators[0], All):
return validators[0].with_validator(validators[1:])
return cls(*validators)
@property
def if_missing(self):
for validator in self.validators:
v = validator.if_missing
if v is not NoDefault:
return v
return NoDefault
@property
def not_empty(self):
not_empty = False
for validator in self.validators:
not_empty = not_empty or getattr(validator, 'not_empty', False)
return not_empty
def is_empty(self, value):
# sub-validators should handle emptiness.
return False
@property
def accept_iterator(self):
accept_iterator = True
for validator in self.validators:
accept_iterator = accept_iterator and getattr(
validator, 'accept_iterator', False)
return accept_iterator
class Pipe(All):
"""Pipe value through all specified validators.
This class works like `All` but the order of evaluation is opposite. All
validators must work, and the results are passed in turn through
each validator for conversion in the order of evaluation. A behaviour
known to Unix and GNU users as 'pipe'.
The order of evaluation differs depending on if you are validating to
Python or from Python as follows:
The validators are evaluated left to right when validating to Python.
The validators are evaluated right to left when validating from Python.
Examples::
>>> from formencode.validators import DictConverter
>>> pv = Pipe(validators=[DictConverter({1: 2}),
... DictConverter({2: 3}), DictConverter({3: 4})])
>>> pv.to_python(1)
4
>>> pv.from_python(4)
1
"""
def __repr__(self):
return '<Pipe %s>' % self.validators
def _attempt_convert(self, value, state, validate):
# To preserve the order of the transformations, we do them
# differently when we are converting to and from Python.
validators = self.validators
if validate is from_python:
validators = reversed(self.validators)
try:
for validator in validators:
value = validate(validator, value, state)
except Invalid:
if self.if_invalid is NoDefault:
raise
return self.if_invalid
return value
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