# copyright 2003-2010 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
#
# This file is part of CubicWeb.
#
# CubicWeb is free software: you can redistribute it and/or modify it under the
# terms of the GNU Lesser General Public License as published by the Free
# Software Foundation, either version 2.1 of the License, or (at your option)
# any later version.
#
# CubicWeb is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License along
# with CubicWeb. If not, see <http://www.gnu.org/licenses/>.
""".. _Selectors:
Selectors
---------
Using and combining existant selectors
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
You can combine selectors using the `&`, `|` and `~` operators.
When two selectors are combined using the `&` operator, it means that
both should return a positive score. On success, the sum of scores is
returned.
When two selectors are combined using the `|` operator, it means that
one of them should return a positive score. On success, the first
positive score is returned.
You can also "negate" a selector by precedeing it by the `~` unary operator.
Of course you can use parenthesis to balance expressions.
Example
~~~~~~~
The goal: when on a blog, one wants the RSS link to refer to blog entries, not to
the blog entity itself.
To do that, one defines a method on entity classes that returns the
RSS stream url for a given entity. The default implementation on
:class:`~cubicweb.entities.AnyEntity` (the generic entity class used
as base for all others) and a specific implementation on `Blog` will
do what we want.
But when we have a result set containing several `Blog` entities (or
different entities), we don't know on which entity to call the
aforementioned method. In this case, we keep the generic behaviour.
Hence we have two cases here, one for a single-entity rsets, the other for
multi-entities rsets.
In web/views/boxes.py lies the RSSIconBox class. Look at its selector:
.. sourcecode:: python
class RSSIconBox(ExtResourcesBoxTemplate):
''' just display the RSS icon on uniform result set '''
__select__ = ExtResourcesBoxTemplate.__select__ & non_final_entity()
It takes into account:
* the inherited selection criteria (one has to look them up in the class
hierarchy to know the details)
* :class:`~cubicweb.selectors.non_final_entity`, which filters on result sets
containing non final entities (a 'final entity' being synonym for entity
attributes type, eg `String`, `Int`, etc)
This matches our second case. Hence we have to provide a specific component for
the first case:
.. sourcecode:: python
class EntityRSSIconBox(RSSIconBox):
'''just display the RSS icon on uniform result set for a single entity'''
__select__ = RSSIconBox.__select__ & one_line_rset()
Here, one adds the :class:`~cubicweb.selectors.one_line_rset` selector, which
filters result sets of size 1. Thus, on a result set containing multiple
entities, :class:`one_line_rset` makes the EntityRSSIconBox class non
selectable. However for a result set with one entity, the `EntityRSSIconBox`
class will have a higher score than `RSSIconBox`, which is what we wanted.
Of course, once this is done, you have to:
* fill in the call method of `EntityRSSIconBox`
* provide the default implementation of the method returning the RSS stream url
on :class:`~cubicweb.entities.AnyEntity`
* redefine this method on `Blog`.
When to use selectors?
~~~~~~~~~~~~~~~~~~~~~~
Selectors are to be used whenever arises the need of dispatching on the shape or
content of a result set or whatever else context (value in request form params,
authenticated user groups, etc...). That is, almost all the time.
Here is a quick example:
.. sourcecode:: python
class UserLink(component.Component):
'''if the user is the anonymous user, build a link to login else a link
to the connected user object with a logout link
'''
__regid__ = 'loggeduserlink'
def call(self):
if self._cw.session.anonymous_session:
# display login link
...
else:
# display a link to the connected user object with a loggout link
...
The proper way to implement this with |cubicweb| is two have two different
classes sharing the same identifier but with different selectors so you'll get
the correct one according to the context.
.. sourcecode:: python
class UserLink(component.Component):
'''display a link to the connected user object with a loggout link'''
__regid__ = 'loggeduserlink'
__select__ = component.Component.__select__ & authenticated_user()
def call(self):
# display useractions and siteactions
...
class AnonUserLink(component.Component):
'''build a link to login'''
__regid__ = 'loggeduserlink'
__select__ = component.Component.__select__ & anonymous_user()
def call(self):
# display login link
...
The big advantage, aside readability once you're familiar with the
system, is that your cube becomes much more easily customizable by
improving componentization.
.. _CustomSelectors:
Defining your own selectors
~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. autodocstring:: cubicweb.appobject::objectify_selector
In other cases, you can take a look at the following abstract base classes:
.. autoclass:: cubicweb.selectors.ExpectedValueSelector
.. autoclass:: cubicweb.selectors.EClassSelector
.. autoclass:: cubicweb.selectors.EntitySelector
Also, think to use the :func:`lltrace` decorator on your selector class' :meth:`__call__` method
or below the :func:`objectify_selector` decorator of your selector function so it gets
traceable when :class:`traced_selection` is activated (see :ref:`DebuggingSelectors`).
.. autofunction:: cubicweb.selectors.lltrace
.. note::
Selectors __call__ should *always* return a positive integer, and shall never
return `None`.
.. _DebuggingSelectors:
Debugging selection
~~~~~~~~~~~~~~~~~~~
Once in a while, one needs to understand why a view (or any application object)
is, or is not selected appropriately. Looking at which selectors fired (or did
not) is the way. The :class:`cubicweb.selectors.traced_selection` context
manager to help with that, *if you're running your instance in debug mode*.
.. autoclass:: cubicweb.selectors.traced_selection
.. |cubicweb| replace:: *CubicWeb*
"""
__docformat__ = "restructuredtext en"
import logging
from warnings import warn
from logilab.common.deprecation import class_renamed
from logilab.common.compat import all, any
from logilab.common.interface import implements as implements_iface
from yams import BASE_TYPES
from cubicweb import Unauthorized, NoSelectableObject, NotAnEntity, role
# even if not used, let yes here so it's importable through this module
from cubicweb.appobject import Selector, objectify_selector, yes
from cubicweb.vregistry import class_regid
from cubicweb.cwconfig import CubicWebConfiguration
from cubicweb.schema import split_expression
# helpers for debugging selectors
SELECTOR_LOGGER = logging.getLogger('cubicweb.selectors')
TRACED_OIDS = None
def _trace_selector(cls, selector, args, ret):
# /!\ lltrace decorates pure function or __call__ method, this
# means argument order may be different
if isinstance(cls, Selector):
selname = str(cls)
vobj = args[0]
else:
selname = selector.__name__
vobj = cls
if TRACED_OIDS == 'all' or class_regid(vobj) in TRACED_OIDS:
#SELECTOR_LOGGER.warning('selector %s returned %s for %s', selname, ret, cls)
print '%s -> %s for %s(%s)' % (selname, ret, vobj, vobj.__regid__)
def lltrace(selector):
"""use this decorator on your selectors so the becomes traceable with
:class:`traced_selection`
"""
# don't wrap selectors if not in development mode
if CubicWebConfiguration.mode == 'system': # XXX config.debug
return selector
def traced(cls, *args, **kwargs):
ret = selector(cls, *args, **kwargs)
if TRACED_OIDS is not None:
_trace_selector(cls, selector, args, ret)
return ret
traced.__name__ = selector.__name__
traced.__doc__ = selector.__doc__
return traced
class traced_selection(object):
"""
Typical usage is :
.. sourcecode:: python
>>> from cubicweb.selectors import traced_selection
>>> with traced_selection():
... # some code in which you want to debug selectors
... # for all objects
Don't forget the 'from __future__ import with_statement' at the module top-level
if you're using python prior to 2.6.
This will yield lines like this in the logs::
selector one_line_rset returned 0 for <class 'cubicweb.web.views.basecomponents.WFHistoryVComponent'>
You can also give to :class:`traced_selection` the identifiers of objects on
which you want to debug selection ('oid1' and 'oid2' in the example above).
.. sourcecode:: python
>>> with traced_selection( ('regid1', 'regid2') ):
... # some code in which you want to debug selectors
... # for objects with __regid__ 'regid1' and 'regid2'
A potentially usefull point to set up such a tracing function is
the `cubicweb.vregistry.Registry.select` method body.
"""
def __init__(self, traced='all'):
self.traced = traced
def __enter__(self):
global TRACED_OIDS
TRACED_OIDS = self.traced
def __exit__(self, exctype, exc, traceback):
global TRACED_OIDS
TRACED_OIDS = None
return traceback is None
def score_interface(etypesreg, cls_or_inst, cls, iface):
"""Return XXX if the give object (maybe an instance or class) implements
the interface.
"""
if getattr(iface, '__registry__', None) == 'etypes':
# adjust score if the interface is an entity class
parents = etypesreg.parent_classes(cls_or_inst.__regid__)
if iface is cls:
return len(parents) + 4
if iface is parents[-1]: # Any
return 1
for index, basecls in enumerate(reversed(parents[:-1])):
if iface is basecls:
return index + 3
return 0
if implements_iface(cls_or_inst, iface):
# implenting an interface takes precedence other special Any interface
return 2
return 0
# abstract selectors / mixin helpers ###########################################
class PartialSelectorMixIn(object):
"""convenience mix-in for selectors that will look into the containing
class to find missing information.
cf. `cubicweb.web.action.LinkToEntityAction` for instance
"""
def __call__(self, cls, *args, **kwargs):
self.complete(cls)
return super(PartialSelectorMixIn, self).__call__(cls, *args, **kwargs)
class ImplementsMixIn(object):
"""mix-in class for selectors checking implemented interfaces of something
"""
def __init__(self, *expected_ifaces, **kwargs):
super(ImplementsMixIn, self).__init__(**kwargs)
self.expected_ifaces = expected_ifaces
def __str__(self):
return '%s(%s)' % (self.__class__.__name__,
','.join(str(s) for s in self.expected_ifaces))
def score_interfaces(self, req, cls_or_inst, cls):
score = 0
etypesreg = req.vreg['etypes']
for iface in self.expected_ifaces:
if isinstance(iface, basestring):
# entity type
try:
iface = etypesreg.etype_class(iface)
except KeyError:
continue # entity type not in the schema
score += score_interface(etypesreg, cls_or_inst, cls, iface)
return score
class EClassSelector(Selector):
"""abstract class for selectors working on *entity class(es)* specified
explicitly or found of the result set.
Here are entity lookup / scoring rules:
* if `entity` is specified, return score for this entity's class
* elif `row` is specified, return score for the class of the entity
found in the specified cell, using column specified by `col` or 0
* else return the sum of scores for each entity class found in the column
specified specified by the `col` argument or in column 0 if not specified,
unless:
- `once_is_enough` is False (the default) and some entity class is scored
to 0, in which case 0 is returned
- `once_is_enough` is True, in which case the first non-zero score is
returned
- `accept_none` is False and some cell in the column has a None value
(this may occurs with outer join)
"""
def __init__(self, once_is_enough=False, accept_none=True):
self.once_is_enough = once_is_enough
self.accept_none = accept_none
@lltrace
def __call__(self, cls, req, rset=None, row=None, col=0, **kwargs):
if kwargs.get('entity'):
return self.score_class(kwargs['entity'].__class__, req)
if not rset:
return 0
score = 0
if row is None:
if not self.accept_none:
if any(rset[i][col] is None for i in xrange(len(rset))):
return 0
for etype in rset.column_types(col):
if etype is None: # outer join
return 0
escore = self.score(cls, req, etype)
if not escore and not self.once_is_enough:
return 0
elif self.once_is_enough:
return escore
score += escore
else:
etype = rset.description[row][col]
if etype is not None:
score = self.score(cls, req, etype)
return score
def score(self, cls, req, etype):
if etype in BASE_TYPES:
return 0
return self.score_class(req.vreg['etypes'].etype_class(etype), req)
def score_class(self, eclass, req):
raise NotImplementedError()
class EntitySelector(EClassSelector):
"""abstract class for selectors working on *entity instance(s)* specified
explicitly or found of the result set.
Here are entity lookup / scoring rules:
* if `entity` is specified, return score for this entity
* elif `row` is specified, return score for the entity found in the
specified cell, using column specified by `col` or 0
* else return the sum of scores for each entity found in the column
specified specified by the `col` argument or in column 0 if not specified,
unless:
- `once_is_enough` is False (the default) and some entity is scored
to 0, in which case 0 is returned
- `once_is_enough` is True, in which case the first non-zero score is
returned
- `accept_none` is False and some cell in the column has a None value
(this may occurs with outer join)
.. Note::
using :class:`EntitySelector` or :class:`EClassSelector` as base selector
class impacts performance, since when no entity or row is specified the
later works on every different *entity class* found in the result set,
while the former works on each *entity* (eg each row of the result set),
which may be much more costly.
"""
@lltrace
def __call__(self, cls, req, rset=None, row=None, col=0, **kwargs):
if not rset and not kwargs.get('entity'):
return 0
score = 0
if kwargs.get('entity'):
score = self.score_entity(kwargs['entity'])
elif row is None:
col = col or 0
for row, rowvalue in enumerate(rset.rows):
if rowvalue[col] is None: # outer join
if not self.accept_none:
return 0
continue
escore = self.score(req, rset, row, col)
if not escore and not self.once_is_enough:
return 0
elif self.once_is_enough:
return escore
score += escore
else:
col = col or 0
etype = rset.description[row][col]
if etype is not None: # outer join
score = self.score(req, rset, row, col)
return score
def score(self, req, rset, row, col):
try:
return self.score_entity(rset.get_entity(row, col))
except NotAnEntity:
return 0
def score_entity(self, entity):
raise NotImplementedError()
class ExpectedValueSelector(Selector):
"""Take a list of expected values as initializer argument and store them
into the :attr:`expected` set attribute.
You should implements the :meth:`_get_value(cls, req, **kwargs)` method
which should return the value for the given context. The selector will then
return 1 if the value is expected, else 0.
"""
def __init__(self, *expected):
assert expected, self
self.expected = frozenset(expected)
def __str__(self):
return '%s(%s)' % (self.__class__.__name__,
','.join(sorted(str(s) for s in self.expected)))
@lltrace
def __call__(self, cls, req, **kwargs):
if self._get_value(cls, req, **kwargs) in self.expected:
return 1
return 0
def _get_value(self, cls, req, **kwargs):
raise NotImplementedError()
# bare selectors ##############################################################
class match_kwargs(ExpectedValueSelector):
"""Return non-zero score if parameter names specified as initializer
arguments are specified in the input context. When multiple parameters are
specified, all of them should be specified in the input context. Return a
score corresponding to the number of expected parameters.
"""
@lltrace
def __call__(self, cls, req, **kwargs):
for arg in self.expected:
if not arg in kwargs:
return 0
return len(self.expected)
class appobject_selectable(Selector):
"""Return 1 if another appobject is selectable using the same input context.
Initializer arguments:
* `registry`, a registry name
* `regid`, an object identifier in this registry
"""
def __init__(self, registry, regid):
self.registry = registry
self.regid = regid
def __call__(self, cls, req, **kwargs):
try:
req.vreg[self.registry].select(self.regid, req, **kwargs)
return 1
except NoSelectableObject:
return 0
# rset selectors ##############################################################
@objectify_selector
@lltrace
def none_rset(cls, req, rset=None, **kwargs):
"""Return 1 if the result set is None (eg usually not specified)."""
if rset is None:
return 1
return 0
# XXX == ~ none_rset
@objectify_selector
@lltrace
def any_rset(cls, req, rset=None, **kwargs):
"""Return 1 for any result set, whatever the number of rows in it, even 0."""
if rset is not None:
return 1
return 0
@objectify_selector
@lltrace
def nonempty_rset(cls, req, rset=None, **kwargs):
"""Return 1 for result set containing one ore more rows."""
if rset is not None and rset.rowcount:
return 1
return 0
# XXX == ~ nonempty_rset
@objectify_selector
@lltrace
def empty_rset(cls, req, rset=None, **kwargs):
"""Return 1 for result set which doesn't contain any row."""
if rset is not None and rset.rowcount == 0:
return 1
return 0
# XXX == multi_lines_rset(1)
@objectify_selector
@lltrace
def one_line_rset(cls, req, rset=None, row=None, **kwargs):
"""Return 1 if the result set is of size 1 or if a specific row in the
result set is specified ('row' argument).
"""
if rset is not None and (row is not None or rset.rowcount == 1):
return 1
return 0
class multi_lines_rset(Selector):
"""If `nb`is specified, return 1 if the result set has exactly `nb` row of
result. Else (`nb` is None), return 1 if the result set contains *at least*
two rows.
"""
def __init__(self, nb=None):
self.expected = nb
def match_expected(self, num):
if self.expected is None:
return num > 1
return num == self.expected
@lltrace
def __call__(self, cls, req, rset=None, **kwargs):
return rset is not None and self.match_expected(rset.rowcount)
class multi_columns_rset(multi_lines_rset):
"""If `nb`is specified, return 1 if the result set has exactly `nb` column
per row. Else (`nb` is None), return 1 if the result set contains *at least*
two columns per row. Return 0 for empty result set.
"""
@lltrace
def __call__(self, cls, req, rset=None, **kwargs):
# 'or 0' since we *must not* return None
return rset and self.match_expected(len(rset.rows[0])) or 0
class paginated_rset(Selector):
"""Return 1 or more for result set with more rows than one or more page
size. You can specify expected number of pages to the initializer (default
to one), and you'll get that number of pages as score if the result set is
big enough.
Page size is searched in (respecting order):
* a `page_size` argument
* a `page_size` form parameters
* the :ref:`navigation.page-size` property
"""
def __init__(self, nbpages=1):
assert nbpages > 0
self.nbpages = nbpages
@lltrace
def __call__(self, cls, req, rset=None, **kwargs):
if rset is None:
return 0
page_size = kwargs.get('page_size')
if page_size is None:
page_size = req.form.get('page_size')
if page_size is None:
page_size = req.property_value('navigation.page-size')
else:
page_size = int(page_size)
if rset.rowcount <= (page_size*self.nbpages):
return 0
return self.nbpages
@objectify_selector
@lltrace
def sorted_rset(cls, req, rset=None, **kwargs):
"""Return 1 for sorted result set (e.g. from an RQL query containing an
:ref:ORDERBY clause.
"""
if rset is None:
return 0
rqlst = rset.syntax_tree()
if len(rqlst.children) > 1 or not rqlst.children[0].orderby:
return 0
return 2
# XXX == multi_etypes_rset(1)
@objectify_selector
@lltrace
def one_etype_rset(cls, req, rset=None, col=0, **kwargs):
"""Return 1 if the result set contains entities which are all of the same
type in the column specified by the `col` argument of the input context, or
in column 0.
"""
if rset is None:
return 0
if len(rset.column_types(col)) != 1:
return 0
return 1
class multi_etypes_rset(multi_lines_rset):
"""If `nb` is specified, return 1 if the result set contains `nb` different
types of entities in the column specified by the `col` argument of the input
context, or in column 0. If `nb` is None, return 1 if the result set contains
*at least* two different types of entities.
"""
@lltrace
def __call__(self, cls, req, rset=None, col=0, **kwargs):
# 'or 0' since we *must not* return None
return rset and self.match_expected(len(rset.column_types(col))) or 0
@objectify_selector
def logged_user_in_rset(cls, req, rset=None, row=None, col=0, **kwargs):
"""Return positive score if the result set at the specified row / col
contains the eid of the logged user.
"""
if rset is None:
return 0
return req.user.eid == rset[row or 0][col]
# entity selectors #############################################################
class non_final_entity(EClassSelector):
"""Return 1 for entity of a non final entity type(s). Remember, "final"
entity types are String, Int, etc... This is equivalent to
`implements('Any')` but more optimized.
See :class:`~cubicweb.selectors.EClassSelector` documentation for entity
class lookup / score rules according to the input context.
"""
def score(self, cls, req, etype):
if etype in BASE_TYPES:
return 0
return 1
def score_class(self, eclass, req):
return 1 # necessarily true if we're there
class implements(ImplementsMixIn, EClassSelector):
"""Return non-zero score for entity that are of the given type(s) or
implements at least one of the given interface(s). If multiple arguments are
given, matching one of them is enough.
Entity types should be given as string, the corresponding class will be
fetched from the entity types registry at selection time.
See :class:`~cubicweb.selectors.EClassSelector` documentation for entity
class lookup / score rules according to the input context.
.. note:: when interface is an entity class, the score will reflect class
proximity so the most specific object will be selected.
"""
def score_class(self, eclass, req):
return self.score_interfaces(req, eclass, eclass)
class score_entity(EntitySelector):
"""Return score according to an arbitrary function given as argument which
will be called with input content entity as argument.
This is a very useful selector that will usually interest you since it
allows a lot of things without having to write a specific selector.
See :class:`~cubicweb.selectors.EntitySelector` documentation for entity
lookup / score rules according to the input context.
"""
def __init__(self, scorefunc, once_is_enough=False):
super(score_entity, self).__init__(once_is_enough)
def intscore(*args, **kwargs):
score = scorefunc(*args, **kwargs)
if not score:
return 0
if isinstance(score, (int, long)):
return score
return 1
self.score_entity = intscore
class relation_possible(EntitySelector):
"""Return 1 for entity that supports the relation, provided that the
request's user may do some `action` on it (see below).
The relation is specified by the following initializer arguments:
* `rtype`, the name of the relation
* `role`, the role of the entity in the relation, either 'subject' or
'object', default to 'subject'
* `target_etype`, optional name of an entity type that should be supported
at the other end of the relation
* `action`, a relation schema action (e.g. one of 'read', 'add', 'delete',
default to 'read') which must be granted to the user, else a 0 score will
be returned. Give None if you don't want any permission checking.
* `strict`, boolean (default to False) telling what to do when the user has
not globally the permission for the action (eg the action is not granted
to one of the user's groups)
- when strict is False, if there are some local role defined for this
action (e.g. using rql expressions), then the permission will be
considered as granted
- when strict is True, then the permission will be actually checked for
each entity
Setting `strict` to True impacts performance for large result set since
you'll then get the :class:`~cubicweb.selectors.EntitySelector` behaviour
while otherwise you get the :class:`~cubicweb.selectors.EClassSelector`'s
one. See those classes documentation for entity lookup / score rules
according to the input context.
"""
def __init__(self, rtype, role='subject', target_etype=None,
action='read', strict=False, **kwargs):
super(relation_possible, self).__init__(**kwargs)
self.rtype = rtype
self.role = role
self.target_etype = target_etype
self.action = action
self.strict = strict
# hack hack hack
def __call__(self, cls, req, **kwargs):
if self.strict:
return EntitySelector.__call__(self, cls, req, **kwargs)
return EClassSelector.__call__(self, cls, req, **kwargs)
def score(self, *args):
if self.strict:
return EntitySelector.score(self, *args)
return EClassSelector.score(self, *args)
def _get_rschema(self, eclass):
eschema = eclass.e_schema
try:
if self.role == 'object':
return eschema.objrels[self.rtype]
else:
return eschema.subjrels[self.rtype]
except KeyError:
return None
def score_class(self, eclass, req):
rschema = self._get_rschema(eclass)
if rschema is None:
return 0 # relation not supported
eschema = eclass.e_schema
if self.target_etype is not None:
try:
rdef = rschema.role_rdef(eschema, self.target_etype, self.role)
if self.action and not rdef.may_have_permission(self.action, req):
return 0
except KeyError:
return 0
elif self.action:
return rschema.may_have_permission(self.action, req, eschema, self.role)
return 1
def score_entity(self, entity):
rschema = self._get_rschema(entity)
if rschema is None:
return 0 # relation not supported
if self.action:
if self.target_etype is not None:
rschema = rschema.role_rdef(entity.e_schema, self.target_etype, self.role)
if self.role == 'subject':
if not rschema.has_perm(entity._cw, self.action, fromeid=entity.eid):
return 0
elif not rschema.has_perm(entity._cw, self.action, toeid=entity.eid):
return 0
return 1
class partial_relation_possible(PartialSelectorMixIn, relation_possible):
"""Same as :class:~`cubicweb.selectors.relation_possible`, but will look for
attributes of the selected class to get information which is otherwise
expected by the initializer, except for `action` and `strict` which are kept
as initializer arguments.
This is useful to predefine selector of an abstract class designed to be
customized.
"""
def __init__(self, action='read', **kwargs):
super(partial_relation_possible, self).__init__(None, None, None,
action, **kwargs)
def complete(self, cls):
self.rtype = cls.rtype
self.role = role(cls)
self.target_etype = getattr(cls, 'etype', None)
if self.target_etype is not None:
warn('[3.6] please rename etype to target_etype on %s' % cls,
DeprecationWarning)
else:
self.target_etype = getattr(cls, 'target_etype', None)
class has_related_entities(EntitySelector):
"""Return 1 if entity support the specified relation and has some linked
entities by this relation , optionaly filtered according to the specified
target type.
The relation is specified by the following initializer arguments:
* `rtype`, the name of the relation
* `role`, the role of the entity in the relation, either 'subject' or
'object', default to 'subject'.
* `target_etype`, optional name of an entity type that should be found
at the other end of the relation
See :class:`~cubicweb.selectors.EntitySelector` documentation for entity
lookup / score rules according to the input context.
"""
def __init__(self, rtype, role='subject', target_etype=None, **kwargs):
super(has_related_entities, self).__init__(**kwargs)
self.rtype = rtype
self.role = role
self.target_etype = target_etype
def score_entity(self, entity):
relpossel = relation_possible(self.rtype, self.role, self.target_etype)
if not relpossel.score_class(entity.__class__, entity._cw):
return 0
rset = entity.related(self.rtype, self.role)
if self.target_etype:
return any(r for r in rset.description if r[0] == self.target_etype)
return rset and 1 or 0
class partial_has_related_entities(PartialSelectorMixIn, has_related_entities):
"""Same as :class:~`cubicweb.selectors.has_related_entity`, but will look
for attributes of the selected class to get information which is otherwise
expected by the initializer.
This is useful to predefine selector of an abstract class designed to be
customized.
"""
def __init__(self, **kwargs):
super(partial_has_related_entities, self).__init__(None, None, None,
**kwargs)
def complete(self, cls):
self.rtype = cls.rtype
self.role = role(cls)
self.target_etype = getattr(cls, 'etype', None)
if self.target_etype is not None:
warn('[3.6] please rename etype to target_etype on %s' % cls,
DeprecationWarning)
else:
self.target_etype = getattr(cls, 'target_etype', None)
class has_permission(EntitySelector):
"""Return non-zero score if request's user has the permission to do the
requested action on the entity. `action` is an entity schema action (eg one
of 'read', 'add', 'delete', 'update').
Here are entity lookup / scoring rules:
* if `entity` is specified, check permission is granted for this entity
* elif `row` is specified, check permission is granted for the entity found
in the specified cell
* else check permission is granted for each entity found in the column
specified specified by the `col` argument or in column 0
"""
def __init__(self, action):
self.action = action
# don't use EntitySelector.__call__ but this optimized implementation to
# avoid considering each entity when it's not necessary
@lltrace
def __call__(self, cls, req, rset=None, row=None, col=0, **kwargs):
if kwargs.get('entity'):
return self.score_entity(kwargs['entity'])
if rset is None:
return 0
user = req.user
action = self.action
if row is None:
score = 0
need_local_check = []
geteschema = req.vreg.schema.eschema
for etype in rset.column_types(0):
if etype in BASE_TYPES:
return 0
eschema = geteschema(etype)
if not user.matching_groups(eschema.get_groups(action)):
if eschema.has_local_role(action):
# have to ckeck local roles
need_local_check.append(eschema)
continue
else:
# even a local role won't be enough
return 0
score += 1
if need_local_check:
# check local role for entities of necessary types
for i, row in enumerate(rset):
if not rset.description[i][0] in need_local_check:
continue
if not self.score(req, rset, i, col):
return 0
score += 1
return score
return self.score(req, rset, row, col)
def score_entity(self, entity):
if entity.has_perm(self.action):
return 1
return 0
class has_add_permission(EClassSelector):
"""Return 1 if request's user has the add permission on entity type
specified in the `etype` initializer argument, or according to entity found
in the input content if not specified.
It also check that then entity type is not a strict subobject (e.g. may only
be used as a composed of another entity).
See :class:`~cubicweb.selectors.EClassSelector` documentation for entity
class lookup / score rules according to the input context when `etype` is
not specified.
"""
def __init__(self, etype=None, **kwargs):
super(has_add_permission, self).__init__(**kwargs)
self.etype = etype
@lltrace
def __call__(self, cls, req, **kwargs):
if self.etype is None:
return super(has_add_permission, self).__call__(cls, req, **kwargs)
return self.score(cls, req, self.etype)
def score_class(self, eclass, req):
eschema = eclass.e_schema
if eschema.final or eschema.is_subobject(strict=True) \
or not eschema.has_perm(req, 'add'):
return 0
return 1
class rql_condition(EntitySelector):
"""Return non-zero score if arbitrary rql specified in `expression`
initializer argument return some results for entity found in the input
context. Returned score is the number of items returned by the rql
condition.
`expression` is expected to be a string containing an rql expression, which
must use 'X' variable to represent the context entity and may use 'U' to
represent the request's user.
See :class:`~cubicweb.selectors.EntitySelector` documentation for entity
lookup / score rules according to the input context.
"""
def __init__(self, expression, once_is_enough=False):
super(rql_condition, self).__init__(once_is_enough)
if 'U' in frozenset(split_expression(expression)):
rql = 'Any X WHERE X eid %%(x)s, U eid %%(u)s, %s' % expression
else:
rql = 'Any X WHERE X eid %%(x)s, %s' % expression
self.rql = rql
def __repr__(self):
return u'<rql_condition "%s" at %x>' % (self.rql, id(self))
def score(self, req, rset, row, col):
try:
return len(req.execute(self.rql, {'x': rset[row][col],
'u': req.user.eid}))
except Unauthorized:
return 0
# logged user selectors ########################################################
@objectify_selector
@lltrace
def no_cnx(cls, req, **kwargs):
"""Return 1 if the web session has no connection set. This occurs when
anonymous access is not allowed and user isn't authenticated.
May only be used on the web side, not on the data repository side.
"""
if not req.cnx:
return 1
return 0
@objectify_selector
@lltrace
def authenticated_user(cls, req, **kwargs):
"""Return 1 if the user is authenticated (e.g. not the anonymous user).
May only be used on the web side, not on the data repository side.
"""
if req.session.anonymous_session:
return 0
return 1
# XXX == ~ authenticated_user()
def anonymous_user():
"""Return 1 if the user is not authenticated (e.g. is the anonymous user).
May only be used on the web side, not on the data repository side.
"""
return ~ authenticated_user()
class match_user_groups(ExpectedValueSelector):
"""Return a non-zero score if request's user is in at least one of the
groups given as initializer argument. Returned score is the number of groups
in which the user is.
If the special 'owners' group is given and `rset` is specified in the input
context:
* if `row` is specified check the entity at the given `row`/`col` (default
to 0) is owned by the user
* else check all entities in `col` (default to 0) are owned by the user
"""
@lltrace
def __call__(self, cls, req, rset=None, row=None, col=0, **kwargs):
user = req.user
if user is None:
return int('guests' in self.expected)
score = user.matching_groups(self.expected)
if not score and 'owners' in self.expected and rset:
if row is not None:
if not user.owns(rset[row][col]):
return 0
score = 1
else:
score = all(user.owns(r[col]) for r in rset)
return score
# Web request selectors ########################################################
@objectify_selector
@lltrace
def primary_view(cls, req, view=None, **kwargs):
"""Return 1 if:
* *no view is specified* in the input context
* a view is specified and its `.is_primary()` method return True
This selector is usually used by contextual components that only want to
appears for the primary view of an entity.
"""
if view is not None and not view.is_primary():
return 0
return 1
class match_view(ExpectedValueSelector):
"""Return 1 if a view is specified an as its registry id is in one of the
expected view id given to the initializer.
"""
@lltrace
def __call__(self, cls, req, view=None, **kwargs):
if view is None or not view.__regid__ in self.expected:
return 0
return 1
@objectify_selector
@lltrace
def match_context_prop(cls, req, context=None, **kwargs):
"""Return 1 if:
* no `context` is specified in input context (take care to confusion, here
`context` refers to a string given as an argument to the input context...)
* specified `context` is matching the context property value for the
appobject using this selector
* the appobject's context property value is None
This selector is usually used by contextual components that want to appears
in a configurable place.
"""
if context is None:
return 1
propval = req.property_value('%s.%s.context' % (cls.__registry__,
cls.__regid__))
if not propval:
propval = cls.context
if propval and context != propval:
return 0
return 1
class match_search_state(ExpectedValueSelector):
"""Return 1 if the current request search state is in one of the expected
states given to the initializer.
Known search states are either 'normal' or 'linksearch' (eg searching for an
object to create a relation with another).
This selector is usually used by action that want to appears or not according
to the ui search state.
"""
@lltrace
def __call__(self, cls, req, **kwargs):
try:
if not req.search_state[0] in self.expected:
return 0
except AttributeError:
return 1 # class doesn't care about search state, accept it
return 1
class match_form_params(ExpectedValueSelector):
"""Return non-zero score if parameter names specified as initializer
arguments are specified in request's form parameters. When multiple
parameters are specified, all of them should be found in req.form. Return a
score corresponding to the number of expected parameters.
"""
@lltrace
def __call__(self, cls, req, **kwargs):
for param in self.expected:
if not param in req.form:
return 0
return len(self.expected)
class specified_etype_implements(implements):
"""Return non-zero score if the entity type specified by an 'etype' key
searched in (by priority) input context kwargs and request form parameters
match a known entity type (case insensitivly), and it's associated entity
class is of one of the type(s) given to the initializer or implements at
least one of the given interfaces. If multiple arguments are given, matching
one of them is enough.
Entity types should be given as string, the corresponding class will be
fetched from the entity types registry at selection time.
.. note:: when interface is an entity class, the score will reflect class
proximity so the most specific object will be selected.
This selector is usually used by views holding entity creation forms (since
we've no result set to work on).
"""
@lltrace
def __call__(self, cls, req, **kwargs):
try:
etype = kwargs['etype']
except KeyError:
try:
etype = req.form['etype']
except KeyError:
return 0
else:
# only check this is a known type if etype comes from req.form,
# else we want the error to propagate
try:
etype = req.vreg.case_insensitive_etypes[etype.lower()]
req.form['etype'] = etype
except KeyError:
return 0
score = self.score_class(req.vreg['etypes'].etype_class(etype), req)
if score:
eschema = req.vreg.schema.eschema(etype)
if eschema.has_local_role('add') or eschema.has_perm(req, 'add'):
return score
return 0
# Other selectors ##############################################################
class match_transition(ExpectedValueSelector):
"""Return 1 if:
* a `transition` argument is found in the input context which
has a `.name` attribute matching one of the expected names given to the
initializer
* no transition specified.
"""
@lltrace
def __call__(self, cls, req, transition=None, **kwargs):
# XXX check this is a transition that apply to the object?
if transition is None:
return 1
if transition is not None and getattr(transition, 'name', None) in self.expected:
return 1
return 0
class is_in_state(score_entity):
"""return 1 if entity is in one of the states given as argument list
you should use this instead of your own score_entity x: x.state == 'bla'
selector to avoid some gotchas:
* possible views gives a fake entity with no state
* you must use the latest tr info, not entity.state for repository side
checking of the current state
"""
def __init__(self, *states):
def score(entity, states=set(states)):
try:
return entity.latest_trinfo().new_state.name in states
except AttributeError:
return None
super(is_in_state, self).__init__(score)
## deprecated stuff ############################################################
entity_implements = class_renamed('entity_implements', implements)
class _but_etype(EntitySelector):
"""accept if the given entity types are not found in the result set.
See `EntitySelector` documentation for behaviour when row is not specified.
:param *etypes: entity types (`basestring`) which should be refused
"""
def __init__(self, *etypes):
super(_but_etype, self).__init__()
self.but_etypes = etypes
def score(self, req, rset, row, col):
if rset.description[row][col] in self.but_etypes:
return 0
return 1
but_etype = class_renamed('but_etype', _but_etype, 'use ~implements(*etypes) instead')
# XXX deprecated the one_* variants of selectors below w/ multi_xxx(nb=1)?
# take care at the implementation though (looking for the 'row' argument's
# value)
two_lines_rset = class_renamed('two_lines_rset', multi_lines_rset)
two_cols_rset = class_renamed('two_cols_rset', multi_columns_rset)
two_etypes_rset = class_renamed('two_etypes_rset', multi_etypes_rset)