"""The `ResultSet` class which is returned as result of a rql query
:organization: Logilab
:copyright: 2001-2008 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr
"""
__docformat__ = "restructuredtext en"
from logilab.common.decorators import cached, clear_cache, copy_cache
from rql import nodes
from cubicweb import NotAnEntity
class ResultSet(object):
"""a result set wrap a RQL query result. This object implements a partial
list protocol to allow direct use as a list of result rows.
:type rowcount: int
:ivar rowcount: number of rows in the result
:type rows: list
:ivar rows: list of rows of result
:type description: list
:ivar description:
result's description, using the same structure as the result itself
:type rql: str or unicode
:ivar rql: the original RQL query string
"""
def __init__(self, results, rql, args=None, description=(), cachekey=None,
rqlst=None):
self.rows = results
self.rowcount = results and len(results) or 0
# original query and arguments
self.rql = rql
self.args = args
self.cachekey = cachekey
# entity types for each cell (same shape as rows)
# maybe discarded if specified when the query has been executed
self.description = description
# parsed syntax tree
if rqlst is not None:
rqlst.schema = None # reset schema in case of pyro transfert
self._rqlst = rqlst
# set to (limit, offset) when a result set is limited using the
# .limit method
self.limited = None
# set by the cursor which returned this resultset
self.vreg = None
self.req = None
def __str__(self):
if not self.rows:
return '<empty resultset %s>' % self.rql
return '<resultset %s (%s rows)>' % (self.rql, len(self.rows))
def __repr__(self):
if not self.rows:
return '<empty resultset for %r>' % self.rql
if not self.description:
return '<resultset %r: %s>' % (self.rql, '\n'.join(str(r) for r in self.rows))
return '<resultset %r: %s>' % (self.rql,
'\n'.join('%s (%s)' % (r, d)
for r, d in zip(self.rows, self.description)))
@cached
def possible_actions(self):
return self.vreg.possible_vobjects('actions', self.req, self)
def __len__(self):
"""returns the result set's size"""
return self.rowcount
def __nonzero__(self):
return self.rowcount
def __getitem__(self, i):
"""returns the ith element of the result set"""
return self.rows[i] #ResultSetRow(self.rows[i])
def __getslice__(self, i, j):
"""returns slice [i:j] of the result set"""
return self.rows[i:j]
def __iter__(self):
"""Returns an iterator over rows"""
return iter(self.rows)
def __add__(self, rset):
# XXX buggy implementation (.rql and .args attributes at least much
# probably differ)
# at least rql could be fixed now that we have union and sub-queries
# but I tend to think that since we have that, we should not need this
# method anymore (syt)
rset = ResultSet(self.rows+rset.rows, self.rql, self.args,
self.description +rset.description)
return self.req.decorate_rset(rset)
def _prepare_copy(self, rows, descr):
rset = ResultSet(rows, self.rql, self.args, descr)
return self.req.decorate_rset(rset)
def transformed_rset(self, transformcb):
""" the result set according to a given column types
:type transormcb: callable(row, desc)
:param transformcb:
a callable which should take a row and its type description as
parameters, and return the transformed row and type description.
:type col: int
:param col: the column index
:rtype: `ResultSet`
"""
rows, descr = [], []
rset = self._prepare_copy(rows, descr)
for row, desc in zip(self.rows, self.description):
nrow, ndesc = transformcb(row, desc)
if ndesc: # transformcb returns None for ndesc to skip that row
rows.append(nrow)
descr.append(ndesc)
rset.rowcount = len(rows)
return rset
def filtered_rset(self, filtercb, col=0):
"""filter the result set according to a given filtercb
:type filtercb: callable(entity)
:param filtercb:
a callable which should take an entity as argument and return
False if it should be skipped, else True
:type col: int
:param col: the column index
:rtype: `ResultSet`
"""
rows, descr = [], []
rset = self._prepare_copy(rows, descr)
for i in xrange(len(self)):
if not filtercb(self.get_entity(i, col)):
continue
rows.append(self.rows[i])
descr.append(self.description[i])
rset.rowcount = len(rows)
return rset
def sorted_rset(self, keyfunc, reverse=False, col=0):
"""sorts the result set according to a given keyfunc
:type keyfunc: callable(entity)
:param keyfunc:
a callable which should take an entity as argument and return
the value used to compare and sort
:type reverse: bool
:param reverse: if the result should be reversed
:type col: int
:param col: the column index. if col = -1, the whole row are used
:rtype: `ResultSet`
"""
rows, descr = [], []
rset = self._prepare_copy(rows, descr)
if col >= 0:
entities = sorted(enumerate(self.entities(col)),
key=lambda (i, e): keyfunc(e), reverse=reverse)
else:
entities = sorted(enumerate(self),
key=lambda (i, e): keyfunc(e), reverse=reverse)
for index, entity in entities:
rows.append(self.rows[index])
descr.append(self.description[index])
rset.rowcount = len(rows)
return rset
def split_rset(self, keyfunc=None, col=0, return_dict=False):
"""Splits the result set in multiple result set according to a given key
:type keyfunc: callable(entity or FinalType)
:param keyfunc:
a callable which should take a value of the rset in argument and
return the value used to group the value. If not define, raw value
of the specified columns is used.
:type col: int
:param col: the column index. if col = -1, the whole row are used
:type return_dict: Boolean
:param return_dict: If true, the function return a mapping
(key -> rset) instead of a list of rset
:rtype: List of `ResultSet` or mapping of `ResultSet`
"""
result = []
mapping = {}
for idx, line in enumerate(self):
if col >= 0:
try:
key = self.get_entity(idx,col)
except NotAnEntity:
key = line[col]
else:
key = line
if keyfunc is not None:
key = keyfunc(key)
if key not in mapping:
rows, descr = [], []
rset = self._prepare_copy(rows, descr)
mapping[key] = rset
result.append(rset)
else:
rset = mapping[key]
rset.rows.append(self.rows[idx])
rset.description.append(self.description[idx])
for rset in result:
rset.rowcount = len(rset.rows)
if return_dict:
return mapping
else:
return result
def limit(self, limit, offset=0, inplace=False):
"""limit the result set to the given number of rows optionaly starting
from an index different than 0
:type limit: int
:param limit: the maximum number of results
:type offset: int
:param offset: the offset index
:type inplace: bool
:param inplace:
if true, the result set is modified in place, else a new result set
is returned and the original is left unmodified
:rtype: `ResultSet`
"""
stop = limit+offset
rows = self.rows[offset:stop]
descr = self.description[offset:stop]
if inplace:
rset = self
rset.rows, rset.description = rows, descr
rset.rowcount = len(rows)
clear_cache(rset, 'description_struct')
if offset:
clear_cache(rset, 'get_entity')
# we also have to fix/remove from the request entity cache entities
# which get a wrong rset reference by this limit call
for entity in self.req.cached_entities():
if entity.rset is self:
if offset <= entity.row < stop:
entity.row = entity.row - offset
else:
self.req.drop_entity_cache(entity.eid)
else:
rset = self._prepare_copy(rows, descr)
if not offset:
# can copy built entity caches
copy_cache(rset, 'get_entity', self)
rset.limited = (limit, offset)
return rset
def printable_rql(self, encoded=False):
"""return the result set's origin rql as a string, with arguments
substitued
"""
encoding = self.req.encoding
rqlstr = self.syntax_tree().as_string(encoding, self.args)
# sounds like we get encoded or unicode string due to a bug in as_string
if not encoded:
if isinstance(rqlstr, unicode):
return rqlstr
return unicode(rqlstr, encoding)
else:
if isinstance(rqlstr, unicode):
return rqlstr.encode(encoding)
return rqlstr
# client helper methods ###################################################
def entities(self, col=0):
"""iter on entities with eid in the `col` column of the result set"""
for i in xrange(len(self)):
# may have None values in case of outer join (or aggregat on eid
# hacks)
if self.rows[i][col] is not None:
yield self.get_entity(i, col)
@cached
def get_entity(self, row, col=None):
"""special method for query retreiving a single entity, returns a
partially initialized Entity instance.
WARNING: due to the cache wrapping this function, you should NEVER
give row as a named parameter (i.e. rset.get_entity(req, 0)
is OK but rset.get_entity(row=0, req=req) isn't
:type row,col: int, int
:param row,col:
row and col numbers localizing the entity among the result's table
:return: the partially initialized `Entity` instance
"""
if col is None:
from warnings import warn
msg = 'col parameter will become mandatory in future version'
warn(msg, DeprecationWarning, stacklevel=3)
col = 0
etype = self.description[row][col]
try:
eschema = self.vreg.schema.eschema(etype)
if eschema.is_final():
raise NotAnEntity(etype)
except KeyError:
raise NotAnEntity(etype)
return self._build_entity(row, col)
def _build_entity(self, row, col, _localcache=None):
"""internal method to get a single entity, returns a
partially initialized Entity instance.
partially means that only attributes selected in the RQL
query will be directly assigned to the entity.
:type row,col: int, int
:param row,col:
row and col numbers localizing the entity among the result's table
:return: the partially initialized `Entity` instance
"""
req = self.req
if req is None:
raise AssertionError('dont call get_entity with no req on the result set')
rowvalues = self.rows[row]
eid = rowvalues[col]
assert eid is not None
# return cached entity if exists. This also avoids potential recursion
# XXX should we consider updating a cached entity with possible
# new attributes found in this resultset ?
try:
if hasattr(req, 'is_super_session'):
# this is a Session object which is not caching entities, so we
# have to use a local cache to avoid recursion pb
if _localcache is None:
_localcache = {}
return _localcache[eid]
else:
return req.entity_cache(eid)
except KeyError:
pass
# build entity instance
etype = self.description[row][col]
entity = self.vreg.etype_class(etype)(req, self, row, col)
entity.set_eid(eid)
# cache entity
if _localcache is not None:
_localcache[eid] = entity
req.set_entity_cache(entity)
eschema = entity.e_schema
# try to complete the entity if there are some additional columns
if len(rowvalues) > 1:
rqlst = self.syntax_tree()
if rqlst.TYPE == 'select':
# UNION query, find the subquery from which this entity has been
# found
rqlst = rqlst.locate_subquery(col, etype, self.args)
# take care, due to outer join support, we may find None
# values for non final relation
for i, attr, x in attr_desc_iterator(rqlst, col):
if x == 'subject':
rschema = eschema.subject_relation(attr)
if rschema.is_final():
entity[attr] = rowvalues[i]
continue
tetype = rschema.objects(etype)[0]
card = rschema.rproperty(etype, tetype, 'cardinality')[0]
else:
rschema = eschema.object_relation(attr)
tetype = rschema.subjects(etype)[0]
card = rschema.rproperty(tetype, etype, 'cardinality')[1]
# only keep value if it can't be multivalued
if card in '1?':
if rowvalues[i] is None:
if x == 'subject':
rql = 'Any Y WHERE X %s Y, X eid %s'
else:
rql = 'Any Y WHERE Y %s X, X eid %s'
rrset = ResultSet([], rql % (attr, entity.eid))
req.decorate_rset(rrset)
else:
rrset = self._build_entity(row, i, _localcache).as_rset()
entity.set_related_cache(attr, x, rrset)
return entity
@cached
def syntax_tree(self):
"""get the syntax tree for the source query.
:rtype: rql.stmts.Statement
:return: the RQL syntax tree of the originating query
"""
if self._rqlst:
rqlst = self._rqlst.copy()
# to avoid transport overhead when pyro is used, the schema has been
# unset from the syntax tree
rqlst.schema = self.vreg.schema
self.vreg.rqlhelper.annotate(rqlst)
else:
rqlst = self.vreg.parse(self.req, self.rql, self.args)
return rqlst
@cached
def column_types(self, col):
"""return the list of different types in the column with the given col
index default to 0 (ie the first column)
:type col: int
:param col: the index of the desired column
:rtype: list
:return: the different entities type found in the column
"""
return frozenset(struc[-1][col] for struc in self.description_struct())
@cached
def description_struct(self):
"""return a list describing sequence of results with the same
description, e.g. :
[[0, 4, ('Bug',)]
[[0, 4, ('Bug',), [5, 8, ('Story',)]
[[0, 3, ('Project', 'Version',)]]
"""
result = []
last = None
for i, row in enumerate(self.description):
if row != last:
if last is not None:
result[-1][1] = i - 1
result.append( [i, None, row] )
last = row
if last is not None:
result[-1][1] = i
return result
@cached
def related_entity(self, row, col):
"""try to get the related entity to extract format information if any"""
locate_query_col = col
rqlst = self.syntax_tree()
etype = self.description[row][col]
if self.vreg.schema.eschema(etype).is_final():
# final type, find a better (ambiguous) one
for i in xrange(len(rqlst.children[0].selection)):
if i == col:
continue
coletype = self.description[row][i]
if coletype is None:
continue
if not self.vreg.schema.eschema(coletype).is_final():
etype = coletype
locate_query_col = i
if len(self.column_types(i)) > 1:
break
# UNION query, find the subquery from which this entity has been
# found
select = rqlst.locate_subquery(locate_query_col, etype, self.args)
try:
myvar = select.selection[col].variable
except AttributeError:
# no .selection attribute is available
return None, None
rel = myvar.main_relation()
if rel is not None:
index = rel.children[0].variable.selected_index()
if index is not None:
return self.get_entity(row, index), rel.r_type
return None, None
@cached
def searched_text(self):
"""returns the searched text in case of full-text search
:return: searched text or `None` if the query is not
a full-text query
"""
rqlst = self.syntax_tree()
for rel in rqlst.iget_nodes(nodes.Relation):
if rel.r_type == 'has_text':
__, rhs = rel.get_variable_parts()
return rhs.eval(self.args)
return None
def attr_desc_iterator(rqlst, index=0):
"""return an iterator on a list of 2-uple (index, attr_relation)
localizing attribute relations of the main variable in a result's row
:type rqlst: rql.stmts.Select
:param rqlst: the RQL syntax tree to describe
:return:
a generator on (index, relation, target) describing column being
attribute of the main variable
"""
main = rqlst.selection[index]
for i, term in enumerate(rqlst.selection):
if i == index:
continue
try:
# XXX rewritten const
var = term.variable
except AttributeError:
continue
#varname = var.name
for ref in var.references():
rel = ref.relation()
if rel is None or rel.is_types_restriction():
continue
lhs, rhs = rel.get_variable_parts()
if main.is_equivalent(lhs):
if rhs.is_equivalent(term):
yield (i, rel.r_type, 'subject')
elif main.is_equivalent(rhs):
if lhs.is_equivalent(term):
yield (i, rel.r_type, 'object')