#
# Copyright (c) 2006, 2007 Canonical
#
# Written by Gustavo Niemeyer <gustavo@niemeyer.net>
#
# This file is part of Storm Object Relational Mapper.
#
# Storm 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.
#
# Storm 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 this program. If not, see <http://www.gnu.org/licenses/>.
#
import re
import json
import uuid
from datetime import datetime, date, time, timedelta
from decimal import Decimal
from storm.compat import buffer, bstr, long_int, pickle, string_types, ustr
from storm.exceptions import NoneError
from storm import Undef, has_cextensions
__all__ = [
"VariableFactory",
"Variable",
"LazyValue",
"BoolVariable",
"IntVariable",
"FloatVariable",
"DecimalVariable",
"RawStrVariable",
"UnicodeVariable",
"DateTimeVariable",
"DateVariable",
"TimeVariable",
"TimeDeltaVariable",
"EnumVariable",
"UUIDVariable",
"JSONVariable",
"ListVariable",
]
numeric_types = (int, long_int, float, Decimal)
[docs]class LazyValue(object):
"""Marker to be used as a base class on lazily evaluated values."""
__slots__ = ()
def raise_none_error(column):
if not column:
raise NoneError("None isn't acceptable as a value")
else:
from storm.expr import compile, CompileError
name = column.name
if column.table is not Undef:
try:
table = compile(column.table)
name = "%s.%s" % (table, name)
except CompileError:
pass
raise NoneError("None isn't acceptable as a value for %s" % name)
def VariableFactory(cls, **old_kwargs):
"""Build cls with kwargs of constructor updated by kwargs of call.
This is really an implementation of partial/curry functions, and
is replaced by 'partial' when 2.5+ is in use.
"""
def variable_factory(**new_kwargs):
kwargs = old_kwargs.copy()
kwargs.update(new_kwargs)
return cls(**kwargs)
return variable_factory
try:
from functools import partial as VariableFactory
except ImportError:
pass
[docs]class Variable(object):
"""Basic representation of a database value in Python.
@type column: L{storm.expr.Column}
@ivar column: The column this variable represents.
@type event: L{storm.event.EventSystem}
@ivar event: The event system on which to broadcast events. If
None, no events will be emitted.
"""
_value = Undef
_lazy_value = Undef
_checkpoint_state = Undef
_allow_none = True
_validator = None
_validator_object_factory = None
_validator_attribute = None
column = None
event = None
def __init__(self, value=Undef, value_factory=Undef, from_db=False,
allow_none=True, column=None, event=None, validator=None,
validator_object_factory=None, validator_attribute=None):
"""
@param value: The initial value of this variable. The default
behavior is for the value to stay undefined until it is
set with L{set}.
@param value_factory: If specified, this will immediately be
called to get the initial value.
@param from_db: A boolean value indicating where the initial
value comes from, if C{value} or C{value_factory} are
specified.
@param allow_none: A boolean indicating whether None should be
allowed to be set as the value of this variable.
@param validator: Validation function called whenever trying to
set the variable to a non-db value. The function should
look like validator(object, attr, value), where the first and
second arguments are the result of validator_object_factory()
(or None, if this parameter isn't provided) and the value of
validator_attribute, respectively. When called, the function
should raise an error if the value is unacceptable, or return
the value to be used in place of the original value otherwise.
@type column: L{storm.expr.Column}
@param column: The column that this variable represents. It's
used for reporting better error messages.
@type event: L{EventSystem}
@param event: The event system to broadcast messages with. If
not specified, then no events will be broadcast.
"""
if not allow_none:
self._allow_none = False
if value is not Undef:
self.set(value, from_db)
elif value_factory is not Undef:
self.set(value_factory(), from_db)
if validator is not None:
self._validator = validator
self._validator_object_factory = validator_object_factory
self._validator_attribute = validator_attribute
self.column = column
self.event = event
def get_lazy(self, default=None):
"""Get the current L{LazyValue} without resolving its value.
@param default: If no L{LazyValue} was previously specified,
return this value. Defaults to None.
"""
if self._lazy_value is Undef:
return default
return self._lazy_value
def get(self, default=None, to_db=False):
"""Get the value, resolving it from a L{LazyValue} if necessary.
If the current value is an instance of L{LazyValue}, then the
C{resolve-lazy-value} event will be emitted, to give third
parties the chance to resolve the lazy value to a real value.
@param default: Returned if no value has been set.
@param to_db: A boolean flag indicating whether this value is
destined for the database.
"""
if self._lazy_value is not Undef and self.event is not None:
self.event.emit("resolve-lazy-value", self, self._lazy_value)
value = self._value
if value is Undef:
return default
if value is None:
return None
return self.parse_get(value, to_db)
def set(self, value, from_db=False):
"""Set a new value.
Generally this will be called when an attribute was set in
Python, or data is being loaded from the database.
If the value is different from the previous value (or it is a
L{LazyValue}), then the C{changed} event will be emitted.
@param value: The value to set. If this is an instance of
L{LazyValue}, then later calls to L{get} will try to
resolve the value.
@param from_db: A boolean indicating whether this value has
come from the database.
"""
# FASTPATH This method is part of the fast path. Be careful when
# changing it (try to profile any changes).
if isinstance(value, LazyValue):
self._lazy_value = value
self._checkpoint_state = new_value = Undef
else:
if not from_db and self._validator is not None:
# We use a factory rather than the object itself to prevent
# the cycle object => obj_info => variable => object
value = self._validator(self._validator_object_factory and
self._validator_object_factory(),
self._validator_attribute, value)
self._lazy_value = Undef
if value is None:
if self._allow_none is False:
raise_none_error(self.column)
new_value = None
else:
new_value = self.parse_set(value, from_db)
if from_db:
# Prepare it for being used by the hook below.
value = self.parse_get(new_value, False)
old_value = self._value
self._value = new_value
if (self.event is not None and
(self._lazy_value is not Undef or new_value != old_value)):
if old_value is not None and old_value is not Undef:
old_value = self.parse_get(old_value, False)
self.event.emit("changed", self, old_value, value, from_db)
def delete(self):
"""Delete the internal value.
If there was a value set, then emit the C{changed} event.
"""
old_value = self._value
if old_value is not Undef:
self._value = Undef
if self.event is not None:
if old_value is not None and old_value is not Undef:
old_value = self.parse_get(old_value, False)
self.event.emit("changed", self, old_value, Undef, False)
def is_defined(self):
"""Check whether there is currently a value.
@return: boolean indicating whether there is currently a value
for this variable. Note that if a L{LazyValue} was
previously set, this returns False; it only returns True if
there is currently a real value set.
"""
return self._value is not Undef
def has_changed(self):
"""Check whether the value has changed.
@return: boolean indicating whether the value has changed
since the last call to L{checkpoint}.
"""
return (self._lazy_value is not Undef or
self.get_state() != self._checkpoint_state)
def get_state(self):
"""Get the internal state of this object.
@return: A value which can later be passed to L{set_state}.
"""
return (self._lazy_value, self._value)
def set_state(self, state):
"""Set the internal state of this object.
@param state: A result from a previous call to
L{get_state}. The internal state of this variable will be set
to the state of the variable which get_state was called on.
"""
self._lazy_value, self._value = state
def checkpoint(self):
""""Checkpoint" the internal state.
See L{has_changed}.
"""
self._checkpoint_state = self.get_state()
def copy(self):
"""Make a new copy of this Variable with the same internal state."""
variable = self.__class__.__new__(self.__class__)
variable.set_state(self.get_state())
return variable
def parse_get(self, value, to_db):
"""Convert the internal value to an external value.
Get a representation of this value either for Python or for
the database. This method is only intended to be overridden
in subclasses, not called from external code.
@param value: The value to be converted.
@param to_db: Whether or not this value is destined for the
database.
"""
return value
def parse_set(self, value, from_db):
"""Convert an external value to an internal value.
A value is being set either from Python code or from the
database. Parse it into its internal representation. This
method is only intended to be overridden in subclasses, not
called from external code.
@param value: The value, either from Python code setting an
attribute or from a column in a database.
@param from_db: A boolean flag indicating whether this value
is from the database.
"""
return value
if has_cextensions:
from storm.cextensions import Variable
[docs]class BoolVariable(Variable):
__slots__ = ()
[docs] def parse_set(self, value, from_db):
if not isinstance(value, numeric_types):
raise TypeError("Expected bool, found %r: %r"
% (type(value), value))
return bool(value)
[docs]class IntVariable(Variable):
__slots__ = ()
[docs] def parse_set(self, value, from_db):
if not isinstance(value, numeric_types):
raise TypeError("Expected int, found %r: %r"
% (type(value), value))
return int(value)
[docs]class FloatVariable(Variable):
__slots__ = ()
[docs] def parse_set(self, value, from_db):
if not isinstance(value, numeric_types):
raise TypeError("Expected float, found %r: %r"
% (type(value), value))
return float(value)
[docs]class DecimalVariable(Variable):
__slots__ = ()
[docs] @staticmethod
def parse_set(value, from_db):
if (from_db and isinstance(value, string_types) or
isinstance(value, (int, long_int))):
value = Decimal(value)
elif not isinstance(value, Decimal):
raise TypeError("Expected Decimal, found %r: %r"
% (type(value), value))
return value
[docs] @staticmethod
def parse_get(value, to_db):
if to_db:
return ustr(value)
return value
[docs]class RawStrVariable(Variable):
__slots__ = ()
[docs] def parse_set(self, value, from_db):
if isinstance(value, buffer):
value = bstr(value)
elif not isinstance(value, bstr):
raise TypeError("Expected bytes, found %r: %r"
% (type(value), value))
return value
[docs]class UnicodeVariable(Variable):
__slots__ = ()
[docs] def parse_set(self, value, from_db):
if not isinstance(value, ustr):
raise TypeError("Expected unicode, found %r: %r"
% (type(value), value))
return value
[docs]class DateTimeVariable(Variable):
__slots__ = ("_tzinfo",)
def __init__(self, *args, **kwargs):
self._tzinfo = kwargs.pop("tzinfo", None)
super(DateTimeVariable, self).__init__(*args, **kwargs)
[docs] def parse_set(self, value, from_db):
if from_db:
if isinstance(value, datetime):
pass
elif isinstance(value, string_types):
if " " not in value:
raise ValueError("Unknown date/time format: %r" % value)
date_str, time_str = value.split(" ")
value = datetime(*(_parse_date(date_str) +
_parse_time(time_str)))
else:
raise TypeError("Expected datetime, found %s" % repr(value))
if self._tzinfo is not None:
if value.tzinfo is None:
value = value.replace(tzinfo=self._tzinfo)
else:
value = value.astimezone(self._tzinfo)
else:
if type(value) in (int, long_int, float):
value = datetime.utcfromtimestamp(value)
elif not isinstance(value, datetime):
raise TypeError("Expected datetime, found %s" % repr(value))
if self._tzinfo is not None:
# Since Python 3.6 you can use astimezone on naive datetime
# instances. This assumes the current timezone is the one on
# the system. This may not be what we want since the DB can
# run on a separate machine with a different timezone.
if value.tzinfo is None:
raise ValueError(
"Tried to use a naive datetime in a timezone aware"
"DataTimeVariable"
)
value = value.astimezone(self._tzinfo)
return value
[docs]class DateVariable(Variable):
__slots__ = ()
[docs] def parse_set(self, value, from_db):
if from_db:
if value is None:
return None
if isinstance(value, datetime):
return value.date()
if isinstance(value, date):
return value
if not isinstance(value, string_types):
raise TypeError("Expected date, found %s" % repr(value))
if " " in value:
value, time_str = value.split(" ")
return date(*_parse_date(value))
else:
if isinstance(value, datetime):
return value.date()
if not isinstance(value, date):
raise TypeError("Expected date, found %s" % repr(value))
return value
[docs]class TimeVariable(Variable):
__slots__ = ()
[docs] def parse_set(self, value, from_db):
if from_db:
# XXX Can None ever get here, considering that set() checks for it?
if value is None:
return None
if isinstance(value, time):
return value
if not isinstance(value, string_types):
raise TypeError("Expected time, found %s" % repr(value))
if " " in value:
date_str, value = value.split(" ")
return time(*_parse_time(value))
else:
if isinstance(value, datetime):
return value.time()
if not isinstance(value, time):
raise TypeError("Expected time, found %s" % repr(value))
return value
[docs]class TimeDeltaVariable(Variable):
__slots__ = ()
[docs] def parse_set(self, value, from_db):
if from_db:
# XXX Can None ever get here, considering that set() checks for it?
if value is None:
return None
if isinstance(value, timedelta):
return value
if not isinstance(value, string_types):
raise TypeError("Expected timedelta, found %s" % repr(value))
return _parse_interval(value)
else:
if not isinstance(value, timedelta):
raise TypeError("Expected timedelta, found %s" % repr(value))
return value
[docs]class UUIDVariable(Variable):
__slots__ = ()
[docs] def parse_set(self, value, from_db):
assert uuid is not None, "The uuid module was not found."
if from_db and isinstance(value, string_types):
value = uuid.UUID(value)
elif not isinstance(value, uuid.UUID):
raise TypeError("Expected UUID, found %r: %r"
% (type(value), value))
return value
[docs] def parse_get(self, value, to_db):
if to_db:
return ustr(value)
return value
[docs]class EnumVariable(Variable):
__slots__ = ("_get_map", "_set_map")
def __init__(self, get_map, set_map, *args, **kwargs):
self._get_map = get_map
self._set_map = set_map
Variable.__init__(self, *args, **kwargs)
[docs] def parse_set(self, value, from_db):
if from_db:
return value
try:
return self._set_map[value]
except KeyError:
raise ValueError("Invalid enum value: %s" % repr(value))
[docs] def parse_get(self, value, to_db):
if to_db:
return value
try:
return self._get_map[value]
except KeyError:
raise ValueError("Invalid enum value: %s" % repr(value))
class MutableValueVariable(Variable):
"""
A variable which contains a reference to mutable content. For this kind
of variable, we can't simply detect when a modification has been made, so
we have to synchronize the content of the variable when the store is
flushing current objects, to check if the state has changed.
"""
__slots__ = ("_event_system")
def __init__(self, *args, **kwargs):
self._event_system = None
Variable.__init__(self, *args, **kwargs)
if self.event is not None:
self.event.hook("start-tracking-changes", self._start_tracking)
self.event.hook("object-deleted", self._detect_changes_and_stop)
def _start_tracking(self, obj_info, event_system):
self._event_system = event_system
self.event.hook("stop-tracking-changes", self._stop_tracking)
def _stop_tracking(self, obj_info, event_system):
event_system.unhook("flush", self._detect_changes)
self._event_system = None
def _detect_changes(self, obj_info):
if (self._checkpoint_state is not Undef and
self.get_state() != self._checkpoint_state):
self.event.emit("changed", self, None, self._value, False)
def _detect_changes_and_stop(self, obj_info):
self._detect_changes(obj_info)
if self._event_system is not None:
self._stop_tracking(obj_info, self._event_system)
def get(self, default=None, to_db=False):
if self._event_system is not None:
self._event_system.hook("flush", self._detect_changes)
return super(MutableValueVariable, self).get(default, to_db)
def set(self, value, from_db=False):
if self._event_system is not None:
if isinstance(value, LazyValue):
self._event_system.unhook("flush", self._detect_changes)
else:
self._event_system.hook("flush", self._detect_changes)
super(MutableValueVariable, self).set(value, from_db)
class EncodedValueVariable(MutableValueVariable):
__slots__ = ()
def parse_set(self, value, from_db):
if from_db:
if isinstance(value, buffer):
value = bstr(value)
return self._loads(value)
else:
return value
def parse_get(self, value, to_db):
if to_db:
return self._dumps(value)
else:
return value
def get_state(self):
return (self._lazy_value, self._dumps(self._value))
def set_state(self, state):
self._lazy_value = state[0]
self._value = self._loads(state[1])
[docs]class JSONVariable(EncodedValueVariable):
__slots__ = ()
def __init__(self, *args, **kwargs):
super(JSONVariable, self).__init__(*args, **kwargs)
def _loads(self, value):
json_openers = (u"[", u"{", u"'", u'"')
if isinstance(value, bstr):
raise TypeError(
"Cannot safely assume encoding of byte string %r." % value)
elif isinstance(value, ustr) and value.lstrip().startswith(json_openers):
# For databases like SQLite the data is not automatically decoded
return json.loads(value)
return value
def _dumps(self, value):
# http://www.ietf.org/rfc/rfc4627.txt states that JSON is text-based
# and so we treat it as such here. In other words, this method returns
# unicode and never str.
dump = json.dumps(value, ensure_ascii=False)
if not isinstance(dump, ustr):
# json.dumps() does not always return unicode. See
# http://code.google.com/p/simplejson/issues/detail?id=40 for one
# of many discussions of str/unicode handling in simplejson.
dump = dump.decode("utf-8")
return dump
[docs]class ListVariable(MutableValueVariable):
__slots__ = ("_item_factory",)
def __init__(self, item_factory, *args, **kwargs):
self._item_factory = item_factory
MutableValueVariable.__init__(self, *args, **kwargs)
[docs] def parse_set(self, value, from_db):
if from_db:
item_factory = self._item_factory
return [item_factory(value=val, from_db=from_db).get()
for val in value]
else:
return value
[docs] def parse_get(self, value, to_db):
if to_db:
item_factory = self._item_factory
return [item_factory(value=val, from_db=False) for val in value]
else:
return value
[docs] def get_state(self):
return (self._lazy_value, pickle.dumps(self._value, -1))
[docs] def set_state(self, state):
self._lazy_value = state[0]
self._value = pickle.loads(state[1])
def _parse_time(time_str):
# TODO Add support for timezones.
colons = time_str.count(":")
if not 1 <= colons <= 2:
raise ValueError("Unknown time format: %r" % time_str)
if colons == 2:
hour, minute, second = time_str.split(":")
else:
hour, minute = time_str.split(":")
second = "0"
if "." in second:
second, microsecond = second.split(".")
second = int(second)
microsecond = int(int(microsecond) * 10 ** (6 - len(microsecond)))
return int(hour), int(minute), second, microsecond
return int(hour), int(minute), int(second), 0
def _parse_date(date_str):
if "-" not in date_str:
raise ValueError("Unknown date format: %r" % date_str)
year, month, day = date_str.split("-")
return int(year), int(month), int(day)
def _parse_interval_table():
table = {}
for units, delta in (
("d day days", timedelta),
("h hour hours", lambda x: timedelta(hours=x)),
("m min minute minutes", lambda x: timedelta(minutes=x)),
("s sec second seconds", lambda x: timedelta(seconds=x)),
("ms millisecond milliseconds", lambda x: timedelta(milliseconds=x)),
("microsecond microseconds", lambda x: timedelta(microseconds=x))
):
for unit in units.split():
table[unit] = delta
return table
_parse_interval_table = _parse_interval_table()
_parse_interval_re = re.compile(r"[\s,]*"
r"([-+]?(?:\d\d?:\d\d?(?::\d\d?)?(?:\.\d+)?"
r"|\d+(?:\.\d+)?))"
r"[\s,]*")
def _parse_interval(interval):
result = timedelta(0)
value = None
for token in _parse_interval_re.split(interval):
if not token:
pass
elif ":" in token:
if value is not None:
result += timedelta(days=value)
value = None
h, m, s, ms = _parse_time(token)
result += timedelta(hours=h, minutes=m, seconds=s, microseconds=ms)
elif value is None:
try:
value = float(token)
except ValueError:
raise ValueError("Expected an interval value rather than "
"%r in interval %r" % (token, interval))
else:
unit = _parse_interval_table.get(token)
if unit is None:
raise ValueError("Unsupported interval unit %r in interval %r"
% (token, interval))
result += unit(value)
value = None
if value is not None:
result += timedelta(seconds=value)
return result