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# -*- test-case-name: axiom.test.test_attributes,axiom.test.test_reference -*-
import os
from decimal import Decimal
from epsilon import hotfix
hotfix.require('twisted', 'filepath_copyTo')
from zope.interface import implements
from twisted.python import filepath
from twisted.python.components import registerAdapter
from epsilon.extime import Time
from axiom.slotmachine import Attribute as inmemory
from axiom.errors import NoCrossStoreReferences, BrokenReference
from axiom.iaxiom import IComparison, IOrdering, IColumn, IQuery
_NEEDS_FETCH = object() # token indicating that a value was not found
__metaclass__ = type
class _ComparisonOperatorMuxer:
"""
Collapse comparison operations into calls to a single method with varying
arguments.
"""
def compare(self, other, op):
"""
Override this in a subclass.
"""
raise NotImplementedError()
def __eq__(self, other):
return self.compare(other, '=')
def __ne__(self, other):
return self.compare(other, '!=')
def __gt__(self, other):
return self.compare(other, '>')
def __lt__(self, other):
return self.compare(other, '<')
def __ge__(self, other):
return self.compare(other, '>=')
def __le__(self, other):
return self.compare(other, '<=')
def compare(left, right, op):
# interim: maybe we want objects later? right now strings should be fine
if IColumn.providedBy(right):
return TwoAttributeComparison(left, op, right)
elif right is None:
if op == '=':
negate = False
elif op == '!=':
negate = True
else:
raise TypeError(
"None/NULL does not work with %s comparison" % (op,))
return NullComparison(left, negate)
else:
# convert to constant usable in the database
return AttributeValueComparison(left, op, right)
class _MatchingOperationMuxer:
"""
Collapse string matching operations into calls to a single method with
varying arguments.
"""
def _like(self, negate, firstOther, *others):
others = (firstOther,) + others
likeParts = []
allValues = True
for other in others:
if IColumn.providedBy(other):
likeParts.append(LikeColumn(other))
allValues = False
elif other is None:
# LIKE NULL is a silly condition, but it's allowed.
likeParts.append(LikeNull())
allValues = False
else:
likeParts.append(LikeValue(other))
if allValues:
likeParts = [LikeValue(''.join(others))]
return LikeComparison(self, negate, likeParts)
def like(self, *others):
return self._like(False, *others)
def notLike(self, *others):
return self._like(True, *others)
def startswith(self, other):
return self._like(False, other, '%')
def endswith(self, other):
return self._like(False, '%', other)
_ASC = 'ASC'
_DESC = 'DESC'
class _OrderingMixin:
"""
Provide the C{ascending} and C{descending} attributes to specify sort
direction.
"""
def _asc(self):
return SimpleOrdering(self, _ASC)
def _desc(self):
return SimpleOrdering(self, _DESC)
desc = descending = property(_desc)
asc = ascending = property(_asc)
class _ContainableMixin:
def oneOf(self, seq, negate=False):
"""
Choose items whose attributes are in a fixed set.
X.oneOf([1, 2, 3])
Implemented with the SQL 'in' statement.
"""
return SequenceComparison(self, seq, negate)
def notOneOf(self, seq):
return self.oneOf(seq, negate=True)
class Comparable(_ContainableMixin, _ComparisonOperatorMuxer,
_MatchingOperationMuxer, _OrderingMixin):
"""
Helper for a thing that can be compared like an SQLAttribute (or is in fact
an SQLAttribute). Requires that 'self' have 'type' (Item-subclass) and
'columnName' (str) attributes, as well as an 'infilter' method in the
spirit of SQLAttribute, documented below.
"""
# XXX TODO: improve error reporting
def compare(self, other, sqlop):
return compare(self, other, sqlop)
class SimpleOrdering:
"""
Currently this class is mostly internal. More documentation will follow as
its interface is finalized.
"""
implements(IOrdering)
# maybe this will be a useful public API, for the query something
# something.
isDescending = property(lambda self: self.direction == _DESC)
isAscending = property(lambda self: self.direction == _ASC)
def __init__(self, attribute, direction=''):
self.attribute = attribute
self.direction = direction
def orderColumns(self):
return [(self.attribute, self.direction)]
def __repr__(self):
return repr(self.attribute) + self.direction
def __add__(self, other):
if isinstance(other, SimpleOrdering):
return CompoundOrdering([self, other])
elif isinstance(other, (list, tuple)):
return CompoundOrdering([self] + list(other))
else:
return NotImplemented
def __radd__(self, other):
if isinstance(other, SimpleOrdering):
return CompoundOrdering([other, self])
elif isinstance(other, (list, tuple)):
return CompoundOrdering(list(other) + [self])
else:
return NotImplemented
class CompoundOrdering:
"""
List of SimpleOrdering instances.
"""
implements(IOrdering)
def __init__(self, seq):
self.simpleOrderings = list(seq)
def __repr__(self):
return self.__class__.__name__ + '(' + repr(self.simpleOrderings) + ')'
def __add__(self, other):
"""
Just thinking about what might be useful from the perspective of
introspecting on query objects... don't document this *too* thoroughly
yet.
"""
if isinstance(other, CompoundOrdering):
return CompoundOrdering(self.simpleOrderings + other.simpleOrderings)
elif isinstance(other, SimpleOrdering):
return CompoundOrdering(self.simpleOrderings + [other])
elif isinstance(other, (list, tuple)):
return CompoundOrdering(self.simpleOrderings + list(other))
else:
return NotImplemented
def __radd__(self, other):
"""
Just thinking about what might be useful from the perspective of
introspecting on query objects... don't document this *too* thoroughly
yet.
"""
if isinstance(other, CompoundOrdering):
return CompoundOrdering(other.simpleOrderings + self.simpleOrderings)
elif isinstance(other, SimpleOrdering):
return CompoundOrdering([other] + self.simpleOrderings)
elif isinstance(other, (list, tuple)):
return CompoundOrdering(list(other) + self.simpleOrderings)
else:
return NotImplemented
def orderColumns(self):
x = []
for o in self.simpleOrderings:
x.extend(o.orderColumns())
return x
class UnspecifiedOrdering:
implements(IOrdering)
def __init__(self, null):
pass
def __add__(self, other):
return IOrdering(other, NotImplemented)
__radd__ = __add__
def orderColumns(self):
return []
registerAdapter(CompoundOrdering, list, IOrdering)
registerAdapter(CompoundOrdering, tuple, IOrdering)
registerAdapter(UnspecifiedOrdering, type(None), IOrdering)
registerAdapter(SimpleOrdering, Comparable, IOrdering)
def compoundIndex(*columns):
for column in columns:
column.compoundIndexes.append(columns)
class SQLAttribute(inmemory, Comparable):
"""
Abstract superclass of all attributes.
_Not_ an attribute itself.
@ivar indexed: A C{bool} indicating whether this attribute will be indexed
in the database.
@ivar default: The value used for this attribute, if no value is specified.
"""
implements(IColumn)
sqltype = None
def __init__(self, doc='', indexed=False, default=None, allowNone=True, defaultFactory=None):
inmemory.__init__(self, doc)
self.indexed = indexed
self.compoundIndexes = []
self.allowNone = allowNone
self.default = default
self.defaultFactory = defaultFactory
if default is not None and defaultFactory is not None:
raise ValueError("You may specify only one of default "
"or defaultFactory, not both")
def computeDefault(self):
if self.defaultFactory is not None:
return self.defaultFactory()
return self.default
def reprFor(self, oself):
return repr(self.__get__(oself))
def getShortColumnName(self, store):
return store.getShortColumnName(self)
def getColumnName(self, store):
return store.getColumnName(self)
def prepareInsert(self, oself, store):
"""
Override this method to do something to an item to prepare for its
insertion into a database.
"""
def coercer(self, value):
"""
must return a value equivalent to the data being passed in for it to be
considered valid for a value of this attribute. for example, 'int' or
'str'.
"""
raise NotImplementedError()
def infilter(self, pyval, oself, store):
"""
used to convert a Python value to something that lives in the database;
so called because it is called when objects go in to the database. It
takes a Python value and returns an SQL value.
"""
raise NotImplementedError()
def outfilter(self, dbval, oself):
"""
used to convert an SQL value to something that lives in memory; so
called because it is called when objects come out of the database. It
takes an SQL value and returns a Python value.
"""
return dbval
# requiredSlots must be called before it's run
prefix = "_axiom_memory_"
dbprefix = "_axiom_store_"
def requiredSlots(self, modname, classname, attrname):
self.modname = modname
self.classname = classname
self.attrname = attrname
self.underlying = self.prefix + attrname
self.dbunderlying = self.dbprefix + attrname
yield self.underlying
yield self.dbunderlying
def fullyQualifiedName(self):
return '.'.join([self.modname,
self.classname,
self.attrname])
def __repr__(self):
return '<%s %s>' % ( self.__class__.__name__, self.fullyQualifiedName())
def type():
def get(self):
if self._type is None:
from twisted.python.reflect import namedAny
self._type = namedAny(self.modname+'.'+self.classname)
return self._type
return get,
_type = None
type = property(*type())
def __get__(self, oself, cls=None):
if cls is not None and oself is None:
if self._type is not None:
assert self._type == cls
else:
self._type = cls
return self
pyval = getattr(oself, self.underlying, _NEEDS_FETCH)
if pyval is _NEEDS_FETCH:
dbval = getattr(oself, self.dbunderlying, _NEEDS_FETCH)
if dbval is _NEEDS_FETCH:
# here is what *is* happening here:
# SQL attributes are always loaded when an Item is created by
# loading from the database, either via a query, a getItemByID
# or an attribute access. If an attribute is left un-set, that
# means that the item it is on was just created, and we fill in
# the default value.
# Here is what *should be*, but *is not* happening here:
# this condition ought to indicate that a value may exist in
# the database, but it is not currently available in memory.
# It would then query the database immediately, loading all
# SQL-resident attributes related to this item to minimize the
# number of queries run (e.g. rather than one per attribute)
# this is a more desireable condition because it means that you
# can create items "for free", so doing, for example,
# self.bar.storeID is a much cheaper operation than doing
# self.bar.baz. This particular idiom is frequently used in
# queries and so speeding it up to avoid having to do a
# database hit unless you actually need an item's attributes
# would be worthwhile.
return self.default
pyval = self.outfilter(dbval, oself)
# An upgrader may have changed the value of this attribute. If so,
# return the new value, not the old one.
if dbval != getattr(oself, self.dbunderlying):
return self.__get__(oself, cls)
# cache python value
setattr(oself, self.underlying, pyval)
return pyval
def loaded(self, oself, dbval):
"""
This method is invoked when the item is loaded from the database, and
when a transaction is reverted which restores this attribute's value.
@param oself: an instance of an item which has this attribute.
@param dbval: the underlying database value which was retrieved.
"""
setattr(oself, self.dbunderlying, dbval)
delattr(oself, self.underlying) # member_descriptors don't raise
# attribute errors; what gives? good
# for us, I guess.
def _convertPyval(self, oself, pyval):
"""
Convert a Python value to a value suitable for inserting into the
database.
@param oself: The object on which this descriptor is an attribute.
@param pyval: The value to be converted.
@return: A value legal for this column in the database.
"""
# convert to dbval later, I guess?
if pyval is None and not self.allowNone:
raise TypeError("attribute [%s.%s = %s()] must not be None" % (
self.classname, self.attrname, self.__class__.__name__))
return self.infilter(pyval, oself, oself.store)
def __set__(self, oself, pyval):
st = oself.store
dbval = self._convertPyval(oself, pyval)
oself.__dirty__[self.attrname] = self, dbval
oself.touch()
setattr(oself, self.underlying, pyval)
setattr(oself, self.dbunderlying, dbval)
if st is not None and st.autocommit:
st._rejectChanges += 1
try:
oself.checkpoint()
finally:
st._rejectChanges -= 1
class TwoAttributeComparison:
implements(IComparison)
def __init__(self, leftAttribute, operationString, rightAttribute):
self.leftAttribute = leftAttribute
self.operationString = operationString
self.rightAttribute = rightAttribute
def getQuery(self, store):
sql = ('(%s %s %s)' % (self.leftAttribute.getColumnName(store),
self.operationString,
self.rightAttribute.getColumnName(store)) )
return sql
def getInvolvedTables(self):
tables = [self.leftAttribute.type]
if self.leftAttribute.type is not self.rightAttribute.type:
tables.append(self.rightAttribute.type)
return tables
def getArgs(self, store):
return []
def __repr__(self):
return ' '.join((self.leftAttribute.fullyQualifiedName(),
self.operationString,
self.rightAttribute.fullyQualifiedName()))
class AttributeValueComparison:
implements(IComparison)
def __init__(self, attribute, operationString, value):
self.attribute = attribute
self.operationString = operationString
self.value = value
def getQuery(self, store):
return ('(%s %s ?)' % (self.attribute.getColumnName(store),
self.operationString))
def getArgs(self, store):
return [self.attribute.infilter(self.value, None, store)]
def getInvolvedTables(self):
return [self.attribute.type]
def __repr__(self):
return ' '.join((self.attribute.fullyQualifiedName(),
self.operationString,
repr(self.value)))
class NullComparison:
implements(IComparison)
def __init__(self, attribute, negate=False):
self.attribute = attribute
self.negate = negate
def getQuery(self, store):
if self.negate:
op = 'NOT'
else:
op = 'IS'
return ('(%s %s NULL)' % (self.attribute.getColumnName(store),
op))
def getArgs(self, store):
return []
def getInvolvedTables(self):
return [self.attribute.type]
class LikeFragment:
def getLikeArgs(self):
return []
def getLikeQuery(self, st):
raise NotImplementedError()
def getLikeTables(self):
return []
class LikeNull(LikeFragment):
def getLikeQuery(self, st):
return "NULL"
class LikeValue(LikeFragment):
def __init__(self, value):
self.value = value
def getLikeQuery(self, st):
return "?"
def getLikeArgs(self):
return [self.value]
class LikeColumn(LikeFragment):
def __init__(self, attribute):
self.attribute = attribute
def getLikeQuery(self, st):
return self.attribute.getColumnName(st)
def getLikeTables(self):
return [self.attribute.type]
class LikeComparison:
implements(IComparison)
# Not AggregateComparison or AttributeValueComparison because there is a
# different, optimized syntax for 'or'. WTF is wrong with you, SQL??
def __init__(self, attribute, negate, likeParts):
self.negate = negate
self.attribute = attribute
self.likeParts = likeParts
def getInvolvedTables(self):
tables = [self.attribute.type]
for lf in self.likeParts:
tables.extend([
t for t in lf.getLikeTables() if t not in tables])
return tables
def getQuery(self, store):
if self.negate:
op = 'NOT LIKE'
else:
op = 'LIKE'
sqlParts = [lf.getLikeQuery(store) for lf in self.likeParts]
sql = '(%s %s (%s))' % (self.attribute.getColumnName(store),
op, ' || '.join(sqlParts))
return sql
def getArgs(self, store):
l = []
for lf in self.likeParts:
for pyval in lf.getLikeArgs():
l.append(
self.attribute.infilter(
pyval, None, store))
return l
class AggregateComparison:
"""
Abstract base class for compound comparisons that aggregate other
comparisons - currently only used for AND and OR comparisons.
"""
implements(IComparison)
operator = None
def __init__(self, *conditions):
self.conditions = conditions
if self.operator is None:
raise NotImplementedError, ('%s cannot be used; you want AND or OR.'
% self.__class__.__name__)
if not conditions:
raise ValueError, ('%s condition requires at least one argument'
% self.operator)
def getQuery(self, store):
oper = ' %s ' % self.operator
return '(%s)' % oper.join(
[condition.getQuery(store) for condition in self.conditions])
def getArgs(self, store):
args = []
for cond in self.conditions:
args += cond.getArgs(store)
return args
def getInvolvedTables(self):
tables = []
for cond in self.conditions:
tables.extend([
t for t in cond.getInvolvedTables() if t not in tables])
return tables
def __repr__(self):
return '%s(%s)' % (self.__class__.__name__,
', '.join(map(repr, self.conditions)))
class SequenceComparison:
implements(IComparison)
def __init__(self, attribute, container, negate):
self.attribute = attribute
self.container = container
self.negate = negate
if IColumn.providedBy(container):
self.containerClause = self._columnContainer
self.getArgs = self._columnArgs
elif IQuery.providedBy(container):
self.containerClause = self._queryContainer
self.getArgs = self._queryArgs
else:
self.containerClause = self._sequenceContainer
self.getArgs = self._sequenceArgs
def _columnContainer(self, store):
"""
Return the fully qualified name of the column being examined so as
to push all of the containment testing into the database.
"""
return self.container.getColumnName(store)
def _columnArgs(self, store):
"""
The IColumn form of this has no arguments, just a column name
specified in the SQL, specified by _columnContainer.
"""
return []
_subselectSQL = None
_subselectArgs = None
def _queryContainer(self, store):
"""
Generate and cache the subselect SQL and its arguments. Return the
subselect SQL.
"""
if self._subselectSQL is None:
sql, args = self.container._sqlAndArgs('SELECT',
self.container._queryTarget)
self._subselectSQL, self._subselectArgs = sql, args
return self._subselectSQL
def _queryArgs(self, store):
"""
Make sure subselect arguments have been generated and then return
them.
"""
self._queryContainer(store)
return self._subselectArgs
_sequence = None
def _sequenceContainer(self, store):
"""
Smash whatever we got into a list and save the result in case we are
executed multiple times. This keeps us from tripping up over
generators and the like.
"""
if self._sequence is None:
self._sequence = list(self.container)
self._clause = ', '.join(['?'] * len(self._sequence))
return self._clause
def _sequenceArgs(self, store):
"""
Filter each element of the data using the attribute type being
tested for containment and hand back the resulting list.
"""
self._sequenceContainer(store) # Force _sequence to be valid
return [self.attribute.infilter(pyval, None, store) for pyval in self._sequence]
# IComparison - getArgs is assigned as an instance attribute
def getQuery(self, store):
return '%s %sIN (%s)' % (
self.attribute.getColumnName(store),
self.negate and 'NOT ' or '',
self.containerClause(store))
def getInvolvedTables(self):
return [self.attribute.type]
class AND(AggregateComparison):
"""
Combine 2 L{IComparison}s such that this is true when both are true.
"""
operator = 'AND'
class OR(AggregateComparison):
"""
Combine 2 L{IComparison}s such that this is true when either is true.
"""
operator = 'OR'
class TableOrderComparisonWrapper(object):
"""
Wrap any other L{IComparison} and override its L{getInvolvedTables} method
to specify the same tables but in an explicitly specified order.
"""
implements(IComparison)
tables = None
comparison = None
def __init__(self, tables, comparison):
assert set(tables) == set(comparison.getInvolvedTables())
self.tables = tables
self.comparison = comparison
def getInvolvedTables(self):
return self.tables
def getQuery(self, store):
return self.comparison.getQuery(store)
def getArgs(self, store):
return self.comparison.getArgs(store)
class boolean(SQLAttribute):
sqltype = 'BOOLEAN'
def infilter(self, pyval, oself, store):
if pyval is None:
return None
if pyval is True:
return 1
elif pyval is False:
return 0
else:
raise TypeError("attribute [%s.%s = boolean()] must be True or False; not %r" %
(self.classname, self.attrname, type(pyval).__name__,))
def outfilter(self, dbval, oself):
if dbval == 1:
return True
elif dbval == 0:
return False
elif self.allowNone and dbval is None:
return None
else:
raise ValueError(
"attribute [%s.%s = boolean()] "
"must have a database value of 1 or 0; not %r" %
(self.classname, self.attrname, dbval))
TOO_BIG = (2 ** 63)-1
class ConstraintError(TypeError):
"""A type constraint was violated.
"""
def __init__(self,
attributeObj,
requiredTypes,
providedValue):
self.attributeObj = attributeObj
self.requiredTypes = requiredTypes
self.providedValue = providedValue
TypeError.__init__(self,
"attribute [%s.%s = %s()] must be "
"(%s); not %r" %
(attributeObj.classname,
attributeObj.attrname,
attributeObj.__class__.__name__,
requiredTypes,
type(providedValue).__name__))
def requireType(attributeObj, value, typerepr, *types):
if not isinstance(value, types):
raise ConstraintError(attributeObj,
typerepr,
value)
inttyperepr = "integer less than %r" % (TOO_BIG,)
class integer(SQLAttribute):
sqltype = 'INTEGER'
def infilter(self, pyval, oself, store):
if pyval is None:
return None
requireType(self, pyval, inttyperepr, int, long)
if pyval > TOO_BIG:
raise ConstraintError(
self, inttyperepr, pyval)
return pyval
class bytes(SQLAttribute):
"""
Attribute representing a sequence of bytes; this is represented in memory
as a Python 'str'.
"""
sqltype = 'BLOB'
def infilter(self, pyval, oself, store):
if pyval is None:
return None
if isinstance(pyval, unicode):
raise ConstraintError(self, "str or other byte buffer", pyval)
return buffer(pyval)
def outfilter(self, dbval, oself):
if dbval is None:
return None
return str(dbval)
class InvalidPathError(ValueError):
"""
A path that could not be used with the database was attempted to be used
with the database.
"""
class text(SQLAttribute):
"""
Attribute representing a sequence of characters; this is represented in
memory as a Python 'unicode'.
"""
def __init__(self, caseSensitive=False, **kw):
SQLAttribute.__init__(self, **kw)
if caseSensitive:
self.sqltype = 'TEXT'
else:
self.sqltype = 'TEXT COLLATE NOCASE'
self.caseSensitive = caseSensitive
def infilter(self, pyval, oself, store):
if pyval is None:
return None
if not isinstance(pyval, unicode) or u'\0' in pyval:
raise ConstraintError(
self, "unicode string without NULL bytes", pyval)
return pyval
def outfilter(self, dbval, oself):
return dbval
class textlist(text):
delimiter = u'\u001f'
# Once upon a time, textlist encoded the list in such a way that caused []
# to be indistinguishable from [u'']. This value is now used as a
# placeholder at the head of the list, to avoid this problem in a way that
# is almost completely backwards-compatible with older databases.
guard = u'\u0002'
def outfilter(self, dbval, oself):
unicodeString = super(textlist, self).outfilter(dbval, oself)
if unicodeString is None:
return None
val = unicodeString.split(self.delimiter)
if val[:1] == [self.guard]:
del val[:1]
return val
def infilter(self, pyval, oself, store):
if pyval is None:
return None
for innerVal in pyval:
assert self.delimiter not in innerVal and self.guard not in innerVal
result = self.delimiter.join([self.guard] + list(pyval))
return super(textlist, self).infilter(result, oself, store)
class path(text):
"""
Attribute representing a pathname in the filesystem. If 'relative=True',
the default, the representative pathname object must be somewhere inside
the store, and will migrate with the store.
I expect L{twisted.python.filepath.FilePath} or compatible objects as my
values.
"""
def __init__(self, relative=True, **kw):
text.__init__(self, **kw)
self.relative = True
def prepareInsert(self, oself, store):
"""
Prepare for insertion into the database by making the dbunderlying
attribute of the item a relative pathname with respect to the store
rather than an absolute pathname.
"""
if self.relative:
fspath = self.__get__(oself)
oself.__dirty__[self.attrname] = self, self.infilter(fspath, oself, store)
def infilter(self, pyval, oself, store):
if pyval is None:
return None
mypath = unicode(pyval.path)
if store is None:
store = oself.store
if store is None:
return None
if self.relative:
# XXX add some more filepath APIs to make this kind of checking easier.
storepath = os.path.normpath(store.filesdir.path)
mysegs = mypath.split(os.sep)
storesegs = storepath.split(os.sep)
if len(mysegs) <= len(storesegs) or mysegs[:len(storesegs)] != storesegs:
raise InvalidPathError('%s not in %s' % (mypath, storepath))
# In the database we use '/' to separate paths for portability.
# This databaes could have relative paths created on Windows, then
# be moved to Linux for deployment, and what *was* the native
# os.sep (backslash) will not be friendly to Linux's filesystem.
# However, this is only for relative paths, since absolute or UNC
# pathnames on a Windows system are inherently unportable and it's
# not reasonable to calculate relative paths outside the store.
p = '/'.join(mysegs[len(storesegs):])
else:
p = mypath # we already know it's absolute, it came from a
# filepath.
return super(path, self).infilter(p, oself, store)
def outfilter(self, dbval, oself):
if dbval is None:
return None
if self.relative:
fp = oself.store.filesdir
for segment in dbval.split('/'):
fp = fp.child(segment)
else:
fp = filepath.FilePath(dbval)
return fp
MICRO = 1000000.
class timestamp(integer):
"""
An in-database representation of date and time.
To make formatting as easy as possible, this is represented in Python as an
instance of L{epsilon.extime.Time}; see its documentation for more details.
"""
def infilter(self, pyval, oself, store):
if pyval is None:
return None
return integer.infilter(self,
int(pyval.asPOSIXTimestamp() * MICRO), oself,
store)
def outfilter(self, dbval, oself):
if dbval is None:
return None
return Time.fromPOSIXTimestamp(dbval / MICRO)
_cascadingDeletes = {}
_disallows = {}
class reference(integer):
NULLIFY = object()
DISALLOW = object()
CASCADE = object()
def __init__(self, doc='', indexed=True, allowNone=True, reftype=None,
whenDeleted=NULLIFY):
integer.__init__(self, doc, indexed, None, allowNone)
assert whenDeleted in (reference.NULLIFY,
reference.CASCADE,
reference.DISALLOW),(
"whenDeleted must be one of: "
"reference.NULLIFY, reference.CASCADE, reference.DISALLOW")
self.reftype = reftype
self.whenDeleted = whenDeleted
if whenDeleted is reference.CASCADE:
# Note; this list is technically in a slightly inconsistent state
# as things are being built.
_cascadingDeletes.setdefault(reftype, []).append(self)
if whenDeleted is reference.DISALLOW:
_disallows.setdefault(reftype, []).append(self)
def reprFor(self, oself):
obj = getattr(oself, self.underlying, None)
if obj is not None:
if obj.storeID is not None:
return 'reference(%d)' % (obj.storeID,)
else:
return 'reference(unstored@%d)' % (id(obj),)
sid = getattr(oself, self.dbunderlying, None)
if sid is None:
return 'None'
return 'reference(%d)' % (sid,)
def __get__(self, oself, cls=None):
"""
Override L{integer.__get__} to verify that the value to be returned is
currently a valid item in the same store, and to make sure that legacy
items are upgraded if they happen to have been cached.
"""
rv = super(reference, self).__get__(oself, cls)
if rv is self:
# If it's an attr lookup on the class, just do that.
return self
if rv is None:
return rv
if not rv._currentlyValidAsReferentFor(oself.store):
# Make sure it's currently valid, i.e. it's not going to be deleted
# this transaction or it hasn't been deleted.
# XXX TODO: drop cached in-memory referent if it's been deleted /
# no longer valid.
assert self.whenDeleted is reference.NULLIFY, (
"not sure what to do if not...")
return None
if rv.__legacy__:
delattr(oself, self.underlying)
return super(reference, self).__get__(oself, cls)
return rv
def prepareInsert(self, oself, store):
oitem = super(reference, self).__get__(oself) # bypass NULLIFY
if oitem is not None and oitem.store is not store:
raise NoCrossStoreReferences(
"Trying to insert item: %r into store: %r, "
"but it has a reference to other item: .%s=%r "
"in another store: %r" % (
oself, store,
self.attrname, oitem,
oitem.store))
def infilter(self, pyval, oself, store):
if pyval is None:
return None
if oself is None:
return pyval.storeID
if oself.store is None:
return pyval.storeID
if oself.store != pyval.store:
raise NoCrossStoreReferences(
"You can't establish references to items in other stores.")
return integer.infilter(self, pyval.storeID, oself, store)
def outfilter(self, dbval, oself):
if dbval is None:
return None
referee = oself.store.getItemByID(dbval, default=None, autoUpgrade=not oself.__legacy__)
if referee is None and self.whenDeleted is not reference.NULLIFY:
# If referee merely changed to another valid referent,
# SQLAttribute.__get__ will notice that what we returned is
# inconsistent and try again. However, it doesn't know about the
# BrokenReference that is raised if the old referee is no longer a
# valid referent. Check to see if the dbunderlying is still the
# same as the dbval passed in. If it's different, we should try to
# load the value again. Only if it is unchanged will we raise the
# BrokenReference. It would be better if all of this
# change-detection logic were in one place, but I can't figure out
# how to do that. -exarkun
if dbval != getattr(oself, self.dbunderlying):
return self.__get__(oself, None)
raise BrokenReference('Reference to storeID %r is broken' % (dbval,))
return referee
class ieee754_double(SQLAttribute):
"""
From the SQLite documentation::
Each value stored in an SQLite database (or manipulated by the
database engine) has one of the following storage classes: (...)
REAL. The value is a floating point value, stored as an 8-byte IEEE
floating point number.
This attribute type implements IEEE754 double-precision binary
floating-point storage. Some people call this 'float', and think it is
somehow related to numbers. This assumption can be misleading when working
with certain types of data.
This attribute name has an unweildy name on purpose. You should be aware
of the caveats related to binary floating point math before using this
type. It is particularly ill-advised to use it to store values
representing large amounts of currency as rounding errors may be
significant enough to introduce accounting discrepancies.
Certain edge-cases are not handled properly. For example, INF and NAN are
considered by SQLite to be equal to everything, rather than the Python
interpretation where INF is equal only to itself and greater than
everything, and NAN is equal to nothing, not even itself.
"""
sqltype = 'REAL'
def infilter(self, pyval, oself, store):
if pyval is None:
return None
requireType(self, pyval, 'float', float)
return pyval
def outfilter(self, dbval, oself):
return dbval
class AbstractFixedPointDecimal(integer):
"""
Attribute representing a number with a specified number of decimal
places.
This is stored in SQLite as a binary integer multiplied by M{10**N}
where C{N} is the number of decimal places required by Python.
Therefore, in-database multiplication, division, or queries which
compare to integers or fixedpointdecimals with a different number of
decimal places, will not work. Also, you cannot store, or sum to, fixed
point decimals greater than M{(2**63)/(10**N)}.
While L{ieee754_double} is handy for representing various floating-point
numbers, such as scientific measurements, this class (and the associated
Python decimal class) is more appropriate for arithmetic on sums of money.
For more information on Python's U{Decimal
class<http://www.python.org/doc/current/lib/module-decimal.html>} and on
general U{computerized Decimal math in
general<http://www2.hursley.ibm.com/decimal/decarith.html>}.
This is currently a private helper superclass because we cannot store
additional metadata about column types; maybe we should fix that.
@cvar decimalPlaces: the number of points of decimal precision allowed by
the storage and retrieval of this class. *Points beyond this number
will be silently truncated to values passed into the database*, so be
sure to select a value appropriate to your application!
"""
def __init__(self, **kw):
integer.__init__(self, **kw)
def infilter(self, pyval, oself, store):
if pyval is None:
return None
if isinstance(pyval, (int, long)):
pyval = Decimal(pyval)
if isinstance(pyval, Decimal):
# Python < 2.5.2 compatibility:
# Use to_integral instead of to_integral_value.
dbval = int((pyval * 10**self.decimalPlaces).to_integral())
return super(AbstractFixedPointDecimal, self).infilter(
dbval, oself, store)
else:
raise TypeError(
"attribute [%s.%s = AbstractFixedPointDecimal(...)] must be "
"Decimal instance; not %r" % (
self.classname, self.attrname, type(pyval).__name__))
def outfilter(self, dbval, oself):
if dbval is None:
return None
return Decimal(dbval) / 10**self.decimalPlaces
def compare(self, other, sqlop):
if isinstance(other, Comparable):
if isinstance(other, AbstractFixedPointDecimal):
if other.decimalPlaces == self.decimalPlaces:
# fall through to default behavior at bottom
pass
else:
raise TypeError(
"Can't compare Decimals of varying precisions: "
"(%s.%s %s %s.%s)" % (
self.classname, self.attrname,
sqlop,
other.classname, other.attrname
))
else:
raise TypeError(
"Can't compare Decimals to other things: "
"(%s.%s %s %s.%s)" % (
self.classname, self.attrname,
sqlop,
other.classname, other.attrname
))
return super(AbstractFixedPointDecimal, self).compare(other, sqlop)
class point1decimal(AbstractFixedPointDecimal):
decimalPlaces = 1
class point2decimal(AbstractFixedPointDecimal):
decimalPlaces = 2
class point3decimal(AbstractFixedPointDecimal):
decimalPlaces = 3
class point4decimal(AbstractFixedPointDecimal):
decimalPlaces = 4
class point5decimal(AbstractFixedPointDecimal):
decimalPlaces = 5
class point6decimal(AbstractFixedPointDecimal):
decimalPlaces = 6
class point7decimal(AbstractFixedPointDecimal):
decimalPlaces = 7
class point8decimal(AbstractFixedPointDecimal):
decimalPlaces = 8
class point9decimal(AbstractFixedPointDecimal):
decimalPlaces = 9
class point10decimal(AbstractFixedPointDecimal):
decimalPlaces = 10
class money(point4decimal):
"""
I am a 4-point precision fixed-point decimal number column type; suggested
for representing a quantity of money.
(This does not, however, include features such as currency.)
"""
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