Files
PyRIGS/zope/schema/_bootstrapfields.py
2014-12-07 17:32:25 +00:00

442 lines
14 KiB
Python

##############################################################################
#
# Copyright (c) 2002 Zope Foundation and Contributors.
# All Rights Reserved.
#
# This software is subject to the provisions of the Zope Public License,
# Version 2.1 (ZPL). A copy of the ZPL should accompany this distribution.
# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
# FOR A PARTICULAR PURPOSE.
#
##############################################################################
"""Bootstrapping fields
"""
__docformat__ = 'restructuredtext'
from zope.interface import Attribute
from zope.interface import providedBy
from zope.interface import implementer
from zope.schema._bootstrapinterfaces import ConstraintNotSatisfied
from zope.schema._bootstrapinterfaces import IContextAwareDefaultFactory
from zope.schema._bootstrapinterfaces import IFromUnicode
from zope.schema._bootstrapinterfaces import NotAContainer
from zope.schema._bootstrapinterfaces import NotAnIterator
from zope.schema._bootstrapinterfaces import RequiredMissing
from zope.schema._bootstrapinterfaces import StopValidation
from zope.schema._bootstrapinterfaces import TooBig
from zope.schema._bootstrapinterfaces import TooLong
from zope.schema._bootstrapinterfaces import TooShort
from zope.schema._bootstrapinterfaces import TooSmall
from zope.schema._bootstrapinterfaces import WrongType
from zope.schema._compat import u
from zope.schema._compat import text_type
from zope.schema._compat import integer_types
from zope.schema._schema import getFields
class ValidatedProperty(object):
def __init__(self, name, check=None):
self._info = name, check
def __set__(self, inst, value):
name, check = self._info
if value != inst.missing_value:
if check is not None:
check(inst, value)
else:
inst.validate(value)
inst.__dict__[name] = value
def __get__(self, inst, owner):
name, check = self._info
return inst.__dict__[name]
class DefaultProperty(ValidatedProperty):
def __get__(self, inst, owner):
name, check = self._info
defaultFactory = inst.__dict__.get('defaultFactory')
# If there is no default factory, simply return the default.
if defaultFactory is None:
return inst.__dict__[name]
# Get the default value by calling the factory. Some factories might
# require a context to produce a value.
if IContextAwareDefaultFactory.providedBy(defaultFactory):
value = defaultFactory(inst.context)
else:
value = defaultFactory()
# Check that the created value is valid.
if check is not None:
check(inst, value)
elif value != inst.missing_value:
inst.validate(value)
return value
class Field(Attribute):
# Type restrictions, if any
_type = None
context = None
# If a field has no assigned value, it will be set to missing_value.
missing_value = None
# This is the default value for the missing_value argument to the
# Field constructor. A marker is helpful since we don't want to
# overwrite missing_value if it is set differently on a Field
# subclass and isn't specified via the constructor.
__missing_value_marker = object()
# Note that the "order" field has a dual existance:
# 1. The class variable Field.order is used as a source for the
# monotonically increasing values used to provide...
# 2. The instance variable self.order which provides a
# monotonically increasing value that tracks the creation order
# of Field (including Field subclass) instances.
order = 0
default = DefaultProperty('default')
# These were declared as slots in zope.interface, we override them here to
# get rid of the dedcriptors so they don't break .bind()
__name__ = None
interface = None
_Element__tagged_values = None
def __init__(self, title=u(''), description=u(''), __name__='',
required=True, readonly=False, constraint=None, default=None,
defaultFactory=None, missing_value=__missing_value_marker):
"""Pass in field values as keyword parameters.
Generally, you want to pass either a title and description, or
a doc string. If you pass no doc string, it will be computed
from the title and description. If you pass a doc string that
follows the Python coding style (title line separated from the
body by a blank line), the title and description will be
computed from the doc string. Unfortunately, the doc string
must be passed as a positional argument.
Here are some examples:
>>> from zope.schema._compat import u
>>> f = Field()
>>> f.__doc__, f.title, f.description
('', u'', u'')
>>> f = Field(title=u('sample'))
>>> f.__doc__, f.title, f.description
(u'sample', u'sample', u'')
>>> f = Field(title=u('sample'), description=u('blah blah\\nblah'))
>>> f.__doc__, f.title, f.description
(u'sample\\n\\nblah blah\\nblah', u'sample', u'blah blah\\nblah')
"""
__doc__ = ''
if title:
if description:
__doc__ = "%s\n\n%s" % (title, description)
else:
__doc__ = title
elif description:
__doc__ = description
super(Field, self).__init__(__name__, __doc__)
self.title = title
self.description = description
self.required = required
self.readonly = readonly
if constraint is not None:
self.constraint = constraint
self.default = default
self.defaultFactory = defaultFactory
# Keep track of the order of field definitions
Field.order += 1
self.order = Field.order
if missing_value is not self.__missing_value_marker:
self.missing_value = missing_value
def constraint(self, value):
return True
def bind(self, object):
clone = self.__class__.__new__(self.__class__)
clone.__dict__.update(self.__dict__)
clone.context = object
return clone
def validate(self, value):
if value == self.missing_value:
if self.required:
raise RequiredMissing(self.__name__)
else:
try:
self._validate(value)
except StopValidation:
pass
def __eq__(self, other):
# should be the same type
if type(self) != type(other):
return False
# should have the same properties
names = {} # used as set of property names, ignoring values
for interface in providedBy(self):
names.update(getFields(interface))
# order will be different always, don't compare it
if 'order' in names:
del names['order']
for name in names:
if getattr(self, name) != getattr(other, name):
return False
return True
def __ne__(self, other):
return not self.__eq__(other)
def _validate(self, value):
if self._type is not None and not isinstance(value, self._type):
raise WrongType(value, self._type, self.__name__)
if not self.constraint(value):
raise ConstraintNotSatisfied(value, self.__name__)
def get(self, object):
return getattr(object, self.__name__)
def query(self, object, default=None):
return getattr(object, self.__name__, default)
def set(self, object, value):
if self.readonly:
raise TypeError("Can't set values on read-only fields "
"(name=%s, class=%s.%s)"
% (self.__name__,
object.__class__.__module__,
object.__class__.__name__))
setattr(object, self.__name__, value)
class Container(Field):
def _validate(self, value):
super(Container, self)._validate(value)
if not hasattr(value, '__contains__'):
try:
iter(value)
except TypeError:
raise NotAContainer(value)
# XXX This class violates the Liskov Substituability Principle: it
# is derived from Container, but cannot be used everywhere an instance
# of Container could be, because it's '_validate' is more restrictive.
class Iterable(Container):
def _validate(self, value):
super(Iterable, self)._validate(value)
# See if we can get an iterator for it
try:
iter(value)
except TypeError:
raise NotAnIterator(value)
class Orderable(object):
"""Values of ordered fields can be sorted.
They can be restricted to a range of values.
Orderable is a mixin used in combination with Field.
"""
min = ValidatedProperty('min')
max = ValidatedProperty('max')
def __init__(self, min=None, max=None, default=None, **kw):
# Set min and max to None so that we can validate if
# one of the super methods invoke validation.
self.min = None
self.max = None
super(Orderable, self).__init__(**kw)
# Now really set min and max
self.min = min
self.max = max
# We've taken over setting default so it can be limited by min
# and max.
self.default = default
def _validate(self, value):
super(Orderable, self)._validate(value)
if self.min is not None and value < self.min:
raise TooSmall(value, self.min)
if self.max is not None and value > self.max:
raise TooBig(value, self.max)
class MinMaxLen(object):
"""Expresses constraints on the length of a field.
MinMaxLen is a mixin used in combination with Field.
"""
min_length = 0
max_length = None
def __init__(self, min_length=0, max_length=None, **kw):
self.min_length = min_length
self.max_length = max_length
super(MinMaxLen, self).__init__(**kw)
def _validate(self, value):
super(MinMaxLen, self)._validate(value)
if self.min_length is not None and len(value) < self.min_length:
raise TooShort(value, self.min_length)
if self.max_length is not None and len(value) > self.max_length:
raise TooLong(value, self.max_length)
@implementer(IFromUnicode)
class Text(MinMaxLen, Field):
"""A field containing text used for human discourse."""
_type = text_type
def __init__(self, *args, **kw):
super(Text, self).__init__(*args, **kw)
def fromUnicode(self, str):
"""
>>> from zope.schema._compat import u
>>> from zope.schema._compat import b
>>> t = Text(constraint=lambda v: 'x' in v)
>>> t.fromUnicode(b("foo x spam"))
Traceback (most recent call last):
...
WrongType: ('foo x spam', <type 'unicode'>, '')
>>> t.fromUnicode(u("foo x spam"))
u'foo x spam'
>>> t.fromUnicode(u("foo spam"))
Traceback (most recent call last):
...
ConstraintNotSatisfied: (u'foo spam', '')
"""
self.validate(str)
return str
class TextLine(Text):
"""A text field with no newlines."""
def constraint(self, value):
return '\n' not in value and '\r' not in value
class Password(TextLine):
"""A text field containing a text used as a password."""
UNCHANGED_PASSWORD = object()
def set(self, context, value):
"""Update the password.
We use a special marker value that a widget can use
to tell us that the password didn't change. This is
needed to support edit forms that don't display the
existing password and want to work together with
encryption.
"""
if value is self.UNCHANGED_PASSWORD:
return
super(Password, self).set(context, value)
def validate(self, value):
try:
existing = bool(self.get(self.context))
except AttributeError:
existing = False
if value is self.UNCHANGED_PASSWORD and existing:
# Allow the UNCHANGED_PASSWORD value, if a password is set already
return
return super(Password, self).validate(value)
class Bool(Field):
"""A field representing a Bool."""
_type = bool
def _validate(self, value):
# Convert integers to bools to they don't get mis-flagged
# by the type check later.
if isinstance(value, int):
value = bool(value)
Field._validate(self, value)
def set(self, object, value):
if isinstance(value, int):
value = bool(value)
Field.set(self, object, value)
def fromUnicode(self, str):
"""
>>> from zope.schema._compat import b
>>> b = Bool()
>>> IFromUnicode.providedBy(b)
True
>>> b.fromUnicode('True')
True
>>> b.fromUnicode('')
False
>>> b.fromUnicode('true')
True
>>> b.fromUnicode('false') or b.fromUnicode('False')
False
"""
v = str == 'True' or str == 'true'
self.validate(v)
return v
@implementer(IFromUnicode)
class Int(Orderable, Field):
"""A field representing an Integer."""
_type = integer_types
def __init__(self, *args, **kw):
super(Int, self).__init__(*args, **kw)
def fromUnicode(self, str):
"""
>>> f = Int()
>>> f.fromUnicode("125")
125
>>> f.fromUnicode("125.6") #doctest: +IGNORE_EXCEPTION_DETAIL
Traceback (most recent call last):
...
ValueError: invalid literal for int(): 125.6
"""
v = int(str)
self.validate(v)
return v