"""
Core classes for validation.
"""
import declarative
import gettext
import os
import re
import textwrap
try:
from pkg_resources import resource_filename
except ImportError:
resource_filename = None
__all__ = ['NoDefault', 'Invalid', 'Validator', 'Identity',
'FancyValidator', 'is_validator']
def get_localedir():
"""
Retrieve the location of locales.
If we're built as an egg, we need to find the resource within the egg.
Otherwise, we need to look for the locales on the filesystem or in the
system message catalog.
"""
locale_dir = ''
# Check the egg first
if resource_filename is not None:
try:
locale_dir = resource_filename(__name__, "/i18n")
except NotImplementedError:
# resource_filename doesn't work with non-egg zip files
pass
if not hasattr(os, 'access'):
# This happens on Google App Engine
return os.path.join(os.path.dirname(__file__), 'i18n')
if os.access(locale_dir, os.R_OK | os.X_OK):
# If the resource is present in the egg, use it
return locale_dir
# Otherwise, search the filesystem
locale_dir = os.path.join(os.path.dirname(__file__), 'i18n')
if not os.access(locale_dir, os.R_OK | os.X_OK):
# Fallback on the system catalog
locale_dir = os.path.normpath('/usr/share/locale')
return locale_dir
def set_stdtranslation(domain="FormEncode", languages=None,
localedir = get_localedir()):
t = gettext.translation(domain=domain,
languages=languages,
localedir=localedir, fallback=True)
global _stdtrans
_stdtrans = t.ugettext
set_stdtranslation()
# Dummy i18n translation function, nothing is translated here.
# Instead this is actually done in api.Validator.message.
# The surrounding _('string') of the strings is only for extracting
# the strings automatically.
# If you run pygettext with this source comment this function out temporarily.
_ = lambda s: s
class NoDefault(object):
"""A dummy value used for parameters with no default."""
def is_validator(obj):
return (isinstance(obj, Validator) or
(isinstance(obj, type) and issubclass(obj, Validator)))
class Invalid(Exception):
"""
This is raised in response to invalid input. It has several
public attributes:
msg:
The message, *without* values substituted. For instance, if
you want HTML quoting of values, you can apply that.
substituteArgs:
The arguments (a dictionary) to go with `msg`.
str(self):
The message describing the error, with values substituted.
value:
The offending (invalid) value.
state:
The state that went with this validator. This is an
application-specific object.
error_list:
If this was a compound validator that takes a repeating value,
and sub-validator(s) had errors, then this is a list of those
exceptions. The list will be the same length as the number of
values -- valid values will have None instead of an exception.
error_dict:
Like `error_list`, but for dictionary compound validators.
"""
def __init__(self, msg,
value, state, error_list=None, error_dict=None):
Exception.__init__(self, msg, value, state, error_list, error_dict)
self.msg = msg
self.value = value
self.state = state
self.error_list = error_list
self.error_dict = error_dict
assert (not self.error_list or not self.error_dict), (
"Errors shouldn't have both error dicts and lists "
"(error %s has %s and %s)"
% (self, self.error_list, self.error_dict))
def __str__(self):
val = self.msg
#if self.value:
# val += " (value: %s)" % repr(self.value)
return val
def __unicode__(self):
if isinstance(self.msg, unicode):
return self.msg
elif isinstance(self.msg, str):
return self.msg.decode('utf8')
else:
return unicode(self.msg)
def unpack_errors(self, encode_variables=False, dict_char='.',
list_char='-'):
"""
Returns the error as a simple data structure -- lists,
dictionaries, and strings.
If ``encode_variables`` is true, then this will return a flat
dictionary, encoded with variable_encode
"""
if self.error_list:
assert not encode_variables, (
"You can only encode dictionary errors")
assert not self.error_dict
result = []
for item in self.error_list:
if not item:
result.append(item)
else:
result.append(item.unpack_errors())
return result
elif self.error_dict:
result = {}
for name, item in self.error_dict.items():
if isinstance(item, (str, unicode)):
result[name] = item
else:
result[name] = item.unpack_errors()
if encode_variables:
import variabledecode
result = variabledecode.variable_encode(result, add_repetitions=False,
dict_char=dict_char,
list_char=list_char)
for key in result.keys():
if not result[key]:
del result[key]
return result
else:
assert not encode_variables, (
"You can only encode dictionary errors")
return self.msg
############################################################
## Base Classes
############################################################
class Validator(declarative.Declarative):
"""
The base class of most validators. See `IValidator` for more, and
`FancyValidator` for the more common (and more featureful) class.
"""
_messages = {}
if_missing = NoDefault
repeating = False
compound = False
gettextargs = {}
use_builtins_gettext = True # In case you don't want to use __builtins__._
# although it may be defined, set this to False
__singletonmethods__ = ('to_python', 'from_python', 'message', 'all_messages',
'subvalidators')
def __classinit__(cls, new_attrs):
if 'messages' in new_attrs:
cls._messages = cls._messages.copy()
cls._messages.update(cls.messages)
del cls.messages
cls._initialize_docstring()
def __init__(self, *args, **kw):
if 'messages' in kw:
self._messages = self._messages.copy()
self._messages.update(kw.pop('messages'))
declarative.Declarative.__init__(self, *args, **kw)
def to_python(self, value, state=None):
return value
def from_python(self, value, state=None):
return value
def message(self, msgName, state, **kw):
# determine translation function
try:
trans = state._
except AttributeError:
try:
if self.use_builtins_gettext:
import __builtin__
trans = __builtin__._
else:
trans = _stdtrans
except AttributeError:
trans = _stdtrans
if not callable(trans):
trans = _stdtrans
msg = self._messages[msgName]
msg = trans(msg, **self.gettextargs)
try:
return msg % kw
except KeyError, e:
raise KeyError(
"Key not found (%s) for %r=%r %% %r (from: %s)"
% (e, msgName, self._messages.get(msgName), kw,
', '.join(self._messages.keys())))
def all_messages(self):
"""
Return a dictionary of all the messages of this validator, and
any subvalidators if present. Keys are message names, values
may be a message or list of messages. This is really just
intended for documentation purposes, to show someone all the
messages that a validator or compound validator (like Schemas)
can produce.
@@: Should this produce a more structured set of messages, so
that messages could be unpacked into a rendered form to see
the placement of all the messages? Well, probably so.
"""
msgs = self._messages.copy()
for v in self.subvalidators():
inner = v.all_messages()
for key, msg in inner:
if key in msgs:
if msgs[key] == msg:
continue
if isinstance(msgs[key], list):
msgs[key].append(msg)
else:
msgs[key] = [msgs[key], msg]
else:
msgs[key] = msg
return msgs
def subvalidators(self):
"""
Return any validators that this validator contains. This is
not useful for functional, except to inspect what values are
available. Specifically the ``.all_messages()`` method uses
this to accumulate all possible messages.
"""
return []
def _initialize_docstring(cls):
"""
This changes the class's docstring to include information
about all the messages this validator uses.
"""
doc = cls.__doc__ or ''
doc = [textwrap.dedent(doc).rstrip()]
messages = cls._messages.items()
messages.sort()
doc.append('\n\n**Messages**\n\n')
for name, default in messages:
default = re.sub(r'(%\(.*?\)[rsifcx])', r'``\1``', default)
doc.append('``'+name+'``:\n')
doc.append(' '+default+'\n\n')
cls.__doc__ = ''.join(doc)
_initialize_docstring = classmethod(_initialize_docstring)
class _Identity(Validator):
def __repr__(self):
return 'validators.Identity'
Identity = _Identity()
class FancyValidator(Validator):
"""
FancyValidator is the (abstract) superclass for various validators
and converters. A subclass can validate, convert, or do both.
There is no formal distinction made here.
Validators have two important external methods:
* .to_python(value, state):
Attempts to convert the value. If there is a problem, or the
value is not valid, an Invalid exception is raised. The
argument for this exception is the (potentially HTML-formatted)
error message to give the user.
* .from_python(value, state):
Reverses to_python.
There are five important methods for subclasses to override,
however none of these *have* to be overridden, only the ones that
are appropriate for the validator:
* __init__():
if the `declarative.Declarative` model doesn't work for this.
* .validate_python(value, state):
This should raise an error if necessary. The value is a Python
object, either the result of to_python, or the input to
from_python.
* .validate_other(value, state):
Validates the source, before to_python, or after from_python.
It's more common to use `.validate_python()` however.
* ._to_python(value, state):
This returns the converted value, or raises an Invalid
exception if there is an error. The argument to this exception
should be the error message.
* ._from_python(value, state):
Should undo .to_python() in some reasonable way, returning
a string.
Validators should have no internal state besides the
values given at instantiation. They should be reusable and
reentrant.
All subclasses can take the arguments/instance variables:
* if_empty:
If set, then this value will be returned if the input evaluates
to false (empty list, empty string, None, etc), but not the 0 or
False objects. This only applies to ``.to_python()``.
* not_empty:
If true, then if an empty value is given raise an error.
(Both with ``.to_python()`` and also ``.from_python()``
if ``.validate_python`` is true).
* strip:
If true and the input is a string, strip it (occurs before empty
tests).
* if_invalid:
If set, then when this validator would raise Invalid during
``.to_python()``, instead return this value.
* if_invalid_python:
If set, when the Python value (converted with
``.from_python()``) is invalid, this value will be returned.
* accept_python:
If True (the default), then ``.validate_python()`` and
``.validate_other()`` will not be called when
``.from_python()`` is used.
"""
if_invalid = NoDefault
if_invalid_python = NoDefault
if_empty = NoDefault
not_empty = False
accept_python = True
strip = False
messages = {
'empty': _("Please enter a value"),
'badType': _("The input must be a string (not a %(type)s: %(value)r)"),
'noneType': _("The input must be a string (not None)"),
}
def to_python(self, value, state=None):
try:
if self.strip and isinstance(value, (str, unicode)):
value = value.strip()
elif hasattr(value, 'mixed'):
# Support Paste's MultiDict
value = value.mixed()
if self.is_empty(value):
if self.not_empty:
raise Invalid(self.message('empty', state), value, state)
else:
if self.if_empty is not NoDefault:
return self.if_empty
else:
return self.empty_value(value)
vo = self.validate_other
if vo and vo is not self._validate_noop:
vo(value, state)
tp = self._to_python
if tp:
value = tp(value, state)
vp = self.validate_python
if vp and vp is not self._validate_noop:
vp(value, state)
return value
except Invalid:
if self.if_invalid is NoDefault:
raise
else:
return self.if_invalid
def from_python(self, value, state=None):
try:
if self.strip and isinstance(value, (str, unicode)):
value = value.strip()
if not self.accept_python:
if self.is_empty(value):
if self.not_empty:
raise Invalid(self.message('empty', state),
value, state)
else:
return self.empty_value(value)
vp = self.validate_python
if vp and vp is not self._validate_noop:
vp(value, state)
fp = self._from_python
if fp:
value = fp(value, state)
vo = self.validate_other
if vo and vo is not self._validate_noop:
vo(value, state)
return value
else:
if self.is_empty(value):
return self.empty_value(value)
fp = self._from_python
if fp:
value = self._from_python(value, state)
return value
except Invalid:
if self.if_invalid_python is NoDefault:
raise
else:
return self.if_invalid_python
def is_empty(self, value):
# None and '' are "empty"
return value is None or value == '' or (
isinstance(value, (list, tuple, dict)) and not value)
def empty_value(self, value):
return None
def assert_string(self, value, state):
if not isinstance(value, (str, unicode)):
raise Invalid(self.message('badType', state,
type=type(value), value=value),
value, state)
def base64encode(self, value):
"""
Encode a string in base64, stripping whitespace and removing
newlines.
"""
return value.encode('base64').strip().replace('\n', '')
def _validate_noop(self, value, state):
"""
A validation method that doesn't do anything.
"""
pass
validate_python = validate_other = _validate_noop
_to_python = None
_from_python = None