def modelWasSet(self):
"""Perform additional set up of the store after the model is set."""
ModelUser.modelWasSet(self)
self._threaded = self.setting('Threaded')
if self._threaded:
self._hasChanges = set() # keep track on a per-thread basis
self._newObjects = PerThreadList()
self._deletedObjects = PerThreadList()
self._changedObjects = PerThreadDict()
else:
self._hasChanges = False
self._newObjects = NonThreadedList()
self._deletedObjects = NonThreadedList()
self._changedObjects = NonThreadedDict()
self._objects = self.emptyObjectCache() # dict; keyed by ObjectKeys
def modelWasSet(self):
"""Perform additional set up of the store after the model is set."""
ModelUser.modelWasSet(self)
self._threaded = self.setting('Threaded')
if self._threaded:
self._hasChanges = set() # keep track on a per-thread basis
self._newObjects = PerThreadList()
self._deletedObjects = PerThreadList()
self._changedObjects = PerThreadDict()
else:
self._hasChanges = False
self._newObjects = NonThreadedList()
self._deletedObjects = NonThreadedList()
self._changedObjects = NonThreadedDict()
self._objects = self.emptyObjectCache() # dict; keyed by ObjectKeys
def modelWasSet(self):
"""
Performs additional set up of the store after the model is set.
"""
ModelUser.modelWasSet(self)
self._threaded = self.setting('Threaded')
if self._threaded:
self._hasChanges = {} # keep track on a per-thread basis
self._newObjects = PerThreadList()
self._deletedObjects = PerThreadList()
self._changedObjects = PerThreadDict()
else:
self._hasChanges = 0
self._newObjects = NonThreadedList()
self._deletedObjects = NonThreadedList()
self._changedObjects = NonThreadedDict()
class ObjectStore(ModelUser):
"""The object store.
NOT IMPLEMENTED:
* revertChanges()
FUTURE
* expanded fetch
"""
## Init ##
def __init__(self):
self._model = None
self._newSerialNum = -1
self._verboseDelete = False
def modelWasSet(self):
"""Perform additional set up of the store after the model is set."""
ModelUser.modelWasSet(self)
self._threaded = self.setting('Threaded')
if self._threaded:
self._hasChanges = set() # keep track on a per-thread basis
self._newObjects = PerThreadList()
self._deletedObjects = PerThreadList()
self._changedObjects = PerThreadDict()
else:
self._hasChanges = False
self._newObjects = NonThreadedList()
self._deletedObjects = NonThreadedList()
self._changedObjects = NonThreadedDict()
self._objects = self.emptyObjectCache() # dict; keyed by ObjectKeys
def emptyObjectCache(self):
if self.setting('CacheObjectsForever', False):
return {}
else:
return WeakValueDictionary()
## Manipulating the objects in the store ##
def hasObject(self, obj):
"""Check if the object is in the store.
Note: this does not check the persistent store.
"""
key = obj.key()
if key is None:
return False
else:
return key in self._objects
def object(self, a, b=NoDefault, c=NoDefault):
"""Return object described by the given arguments, or default value.
store.object(anObjectKey) - return the object with the given key,
or raise a KeyError if it does not reside in memory.
store.object(anObjectKey, defaultValue) - return the object
or defaultValue (no exception will be raised)
store.object(someClass, serialNum) - return the object
of the given class and serial num, or raise a KeyError
store.object(someClass, serialNum, defaultValue) - return the object
or defaultValue (no exception will be raised)
`someClass` can be a Python class, a string (the name of a class)
or a MiddleKit.Core.Klass
"""
if isinstance(a, ObjectKey):
return self.objectForKey(a, b)
else:
return self.objectForClassAndSerial(a, b, c)
def objectForClassAndSerial(self, klass, serialNum, default=NoDefault):
if isinstance(klass, BaseKlass):
klass = klass.name()
elif isinstance(klass, (type, ClassType)):
klass = klass.__name__
else:
assert isinstance(klass, str)
key = ObjectKey().initFromClassNameAndSerialNum(klass, serialNum)
return self.objectForKey(key, default)
def objectForKey(self, key, default=NoDefault):
"""Return an object from the store by its given key.
If no default is given and the object is not in the store,
then an exception is raised. Note: This method doesn't currently
fetch objects from the persistent store.
"""
if default is NoDefault:
return self._objects[key]
else:
return self._objects.get(key, default)
def add(self, obj, noRecurse=False):
return self.addObject(obj, noRecurse)
def addObject(self, obj, noRecurse=False):
"""Add the object and all referenced objects to the store.
You can insert the same object multiple times, and you can insert
an object that was loaded from the store. In those cases, this is
a no-op. The noRecurse flag is used internally, and should be avoided
in regular MiddleKit usage; it causes only this object to be added
to the store, not any dependent objects.
"""
if not obj.isInStore():
assert obj.key() is None
# Make the store aware of this new object
self.willChange()
self._newObjects.append(obj)
obj.setStore(self)
if not noRecurse:
# Recursively add referenced objects to the store
obj.addReferencedObjectsToStore(self)
# 2000-10-07 ce: Decided not to allow keys for non-persisted objects
# Because the serial num, and therefore the key, will change
# upon saving.
# key = obj.key()
# if key is None:
# key = ObjectKey(obj, self)
# obj.setKey(key)
# self._objects[key] = obj
def deleteObject(self, obj):
"""Delete object.
Restrictions: The object must be contained in the store and obviously
you cannot remove it more than once.
"""
# First check if the delete is possible. Then do the actual delete.
# This avoids partially deleting objects only to have an exception
# halt the process in the middle.
objectsToDel = {}
detaches = []
self._deleteObject(obj, objectsToDel, detaches) # compute objectsToDel and detaches
self.willChange()
# detaches
for obj, attr in detaches:
if id(obj) not in objectsToDel:
obj.setValueForAttr(attr, None)
# process final list of objects
objectsToDel = objectsToDel.values()
for obj in objectsToDel:
obj._mk_isDeleted = True
self._deletedObjects.append(obj)
obj.updateReferencingListAttrs()
del self._objects[obj.key()]
def _deleteObject(self, obj, objectsToDel, detaches, superobject=None):
"""Compile the list of objects to be deleted.
This is a recursive method since deleting one object might be
deleting others.
obj - the object to delete
objectsToDel - a running dictionary of all objects to delete
detaches - a running list of all detaches (eg, obj.attr=None)
superobject - the object that was the cause of this invocation
"""
# Some basic assertions
assert self.hasObject(obj), safeDescription(obj)
assert obj.key() is not None
v = self._verboseDelete
if v:
if superobject:
cascadeString = 'cascade-'
dueTo = ' due to deletion of %s.%i' % (
superobject.klass().name(), superobject.serialNum())
else:
cascadeString = dueTo = ''
print 'checking %sdelete of %s.%d%s' % (
cascadeString, obj.klass().name(), obj.serialNum(), dueTo)
objectsToDel[id(obj)] = obj
# Get the objects/attrs that reference this object
referencingObjectsAndAttrs = obj.referencingObjectsAndAttrs()
# cascade-delete objects with onDeleteOther=cascade
for referencingObject, referencingAttr in referencingObjectsAndAttrs:
onDeleteOther = referencingAttr.get('onDeleteOther', 'deny')
if onDeleteOther == 'cascade':
self._deleteObject(referencingObject, objectsToDel, detaches, obj)
# Determine all referenced objects, constructing a list of (attr, referencedObject) tuples.
referencedAttrsAndObjects = obj.referencedAttrsAndObjects()
# Check if it's possible to cascade-delete objects with onDeleteSelf=cascade
for referencedAttr, referencedObject in referencedAttrsAndObjects:
onDeleteSelf = referencedAttr.get('onDeleteSelf', 'detach')
if onDeleteSelf == 'cascade':
self._deleteObject(referencedObject, objectsToDel, detaches, obj)
# Deal with all other objects that reference or are referenced by this object.
# By default, you are not allowed to delete an object that has an ObjRef pointing to it.
# But if the ObjRef has onDeleteOther=detach, then that ObjRef attr will be set to None
# and the delete will be allowed; and if onDeleteOther=cascade, then that object will
# itself be deleted and the delete will be allowed.
#
# You _are_ by default allowed to delete an object that points to other objects
# (by List or ObjRef) but if onDeleteSelf=deny it will be disallowed, or if
# onDeleteSelf=cascade the pointed-to objects will themselves be deleted.
# Remove from that list anything in the cascaded list
referencingObjectsAndAttrs = [(o, a)
for o, a in referencingObjectsAndAttrs if id(o) not in objectsToDel]
# Remove from that list anything in the cascaded list
referencedAttrsAndObjects = [(a, o)
for a, o in referencedAttrsAndObjects if id(o) not in objectsToDel]
# Check for onDeleteOther=deny
badObjectsAndAttrs = []
for referencingObject, referencingAttr in referencingObjectsAndAttrs:
onDeleteOther = referencingAttr.get('onDeleteOther', 'deny')
assert onDeleteOther in ('deny', 'detach', 'cascade')
if onDeleteOther == 'deny':
badObjectsAndAttrs.append((referencingObject, referencingAttr))
if badObjectsAndAttrs:
raise DeleteReferencedError(
'You tried to delete an object (%s.%d) that is referenced'
' by other objects with onDeleteOther unspecified or set to deny'
% (obj.klass().name(), obj.serialNum()), obj, badObjectsAndAttrs)
# Check for onDeleteSelf=deny
badAttrs = []
for referencedAttr, referencedObject in referencedAttrsAndObjects:
onDeleteSelf = referencedAttr.get('onDeleteSelf', 'detach')
assert onDeleteSelf in ['deny', 'detach', 'cascade']
if onDeleteSelf == 'deny':
badAttrs.append(referencedAttr)
if badAttrs:
raise DeleteObjectWithReferencesError(
'You tried to delete an object (%s.%d) that references'
' other objects with onDeleteSelf set to deny'
% (obj.klass().name(), obj.serialNum()), obj, badAttrs)
# Detach objects with onDeleteOther=detach
for referencingObject, referencingAttr in referencingObjectsAndAttrs:
onDeleteOther = referencingAttr.get('onDeleteOther', 'deny')
if onDeleteOther == 'detach':
if v:
print 'will set %s.%d.%s to None' % (
referencingObject.klass().name(),
referencingObject.serialNum(), referencingAttr.name())
detaches.append((referencingObject, referencingAttr))
# Detach objects with onDeleteSelf=detach
# This is actually a no-op. There is nothing that needs to be set to zero.
## Changes ##
def hasChangesForCurrentThread(self):
"""Return whether the current thread has changes to be committed."""
if self._threaded:
threadid = thread.get_ident()
return threadid in self._hasChanges
else:
return self._hasChanges
def hasChanges(self):
"""Return whether any thread has changes to be committed."""
if self._threaded:
return bool(self._hasChanges)
return self._hasChanges
def willChange(self):
if self._threaded:
threadid = thread.get_ident()
self._hasChanges.add(threadid)
else:
self._hasChanges = True
def saveAllChanges(self):
"""Commit object changes to the object store.
Done by invoking commitInserts(), commitUpdates() and commitDeletions()
all of which must by implemented by a concrete subclass.
"""
self.commitDeletions(allThreads=True)
self.commitInserts(allThreads=True)
self.commitUpdates(allThreads=True)
if self._threaded:
self._hasChanges = set()
else:
self._hasChanges = False
def saveChanges(self):
"""Commit object changes to the object store.
Done by invoking commitInserts(), commitUpdates() and commitDeletions()
all of which must by implemented by a concrete subclass.
"""
self.commitDeletions()
self.commitInserts()
self.commitUpdates()
if self._threaded:
self._hasChanges.discard(thread.get_ident())
else:
self._hasChanges = False
def commitInserts(self):
"""Commit inserts.
Invoked by saveChanges() to insert any news objects add since the
last save. Subclass responsibility.
"""
raise AbstractError(self.__class__)
def commitUpdates(self):
"""Commit updates.
Invoked by saveChanges() to update the persistent store with any
changes since the last save.
"""
raise AbstractError(self.__class__)
def commitDeletions(self):
"""Commit deletions.
Invoked by saveChanges() to delete from the persistent store any
objects deleted since the last save. Subclass responsibility.
"""
raise AbstractError(self.__class__)
def revertChanges(self):
"""Revert changes.
Discards all insertions and deletions, and restores changed objects
to their original values.
"""
raise AbstractError(self.__class__)
## Fetching ##
def fetchObject(self, className, serialNum, default=NoDefault):
"""Fetch onkect of a given class.
Subclasses should raise UnknownObjectError if an object with the
given className and serialNum does not exist, unless a default value
was passed in, in which case that value should be returned.
"""
raise AbstractError(self.__class__)
def fetchObjectsOfClass(self, className, isDeep=True):
"""Fetch all objects of a given class.
If isDeep is True, then all subclasses are also returned.
"""
raise AbstractError(self.__class__)
def fetch(self, *args, **namedArgs):
"""An alias for fetchObjectsOfClass()."""
return self.fetchObjectsOfClass(*args, **namedArgs)
## Other ##
def clear(self):
"""Clear all objects from the memory of the store.
This does not delete the objects in the persistent backing.
This method can only be invoked if there are no outstanding changes
to be saved. You can check for that with hasChanges().
"""
assert not self.hasChanges()
assert self._newObjects.isEmpty()
assert self._deletedObjects.isEmpty()
assert self._changedObjects.isEmpty()
self._objects = self.emptyObjectCache()
self._newSerialNum = -1
def discardEverything(self):
"""Discard all cached objects.
This includes any modification tracking. However, objects in memory
will not change state as a result of this call.
This method is a severe form of clear() and is typically used only
for debugging or production emergencies.
"""
if self._threaded:
self._hasChanges = set()
else:
self._hasChanges = False
self._objects = self.emptyObjectCache()
self._newObjects.clear()
self._deletedObjects.clear()
self._changedObjects.clear()
self._newSerialNum = -1
## Notifications ##
def objectChanged(self, obj):
"""Mark attributes as changed.
MiddleObjects must send this message when one of their interesting
attributes change, where an attribute is interesting if it's listed
in the class model. This method records the object in a set for
later processing when the store's changes are saved.
If you subclass MiddleObject, then you're taken care of.
"""
self.willChange()
self._changedObjects[obj] = obj
# @@ 2000-10-06 ce: Should this be keyed by the obj.key()? Does it matter?
## Serial numbers ##
def newSerialNum(self):
"""Return a new serial number for a newly created object.
This is a utility methods for objects that have been created, but
not yet committed to the persistent store. These serial numbers are
actually temporary and replaced upon committal. Also, they are always
negative to indicate that they are temporary, whereas serial numbers
taken from the persistent store are positive.
"""
self._newSerialNum -= 1
return self._newSerialNum
## Self utility ##
def _klassForClass(self, aClass):
"""Return a Klass object for the given class.
This may be:
- the Klass object already
- a Python class
- a class name (e.g., string)
Users of this method include the various fetchObjectEtc() methods
which take a "class" parameter.
"""
assert aClass is not None
if not isinstance(aClass, BaseKlass):
if isinstance(aClass, type): # new Python classes
aClass = self._model.klass(aClass.__name__)
elif isinstance(aClass, ClassType): # old Python classes
aClass = self._model.klass(aClass.__name__)
elif isinstance(aClass, basestring):
aClass = self._model.klass(aClass)
else:
raise ValueError('Invalid class parameter. Pass a Klass,'
'a name or a Python class. Type of aClass is %s.'
' aClass is %s.' % (type(aClass), aClass))
return aClass
class ObjectStore(ModelUser):
"""
NOT IMPLEMENTED:
* revertChanges()
FUTURE
* expanded fetch
"""
## Init ##
def __init__(self):
self._model = None
self._objects = {} # keyed by ObjectKeys
self._newSerialNum = -1
self._verboseDelete = 0
def modelWasSet(self):
"""
Performs additional set up of the store after the model is set.
"""
ModelUser.modelWasSet(self)
self._threaded = self.setting('Threaded')
if self._threaded:
self._hasChanges = {} # keep track on a per-thread basis
self._newObjects = PerThreadList()
self._deletedObjects = PerThreadList()
self._changedObjects = PerThreadDict()
else:
self._hasChanges = 0
self._newObjects = NonThreadedList()
self._deletedObjects = NonThreadedList()
self._changedObjects = NonThreadedDict()
## Settings ##
def setting(self, name, default=NoDefault):
"""
Returns the given setting for the store, which is actually
just taken from the model.
"""
return self._model.setting(name, default)
## Manipulating the objects in the store ##
def hasObject(self, object):
""" Checks if the object is in the store. Note: this does not check the persistent store. """
key = object.key()
if key is None:
return 0
else:
return self._objects.has_key(key)
def object(self, key, default=NoDefault):
""" Returns an object from the store by it's given key. If no default is given and the object is not in the store, then an exception is raised. Note: This method doesn't currently fetch objects from the persistent store. """
if default is NoDefault:
return self._objects[key]
else:
return self._objects.get(key, default)
def addObject(self, object, noRecurse=0):
"""
Add the object and all referenced objects to the store.
You can insert the same object multiple times, and you can insert an object that was
loaded from the store. In those cases, this is a no-op.
The noRecurse flag is used internally, and should be avoided in regular
MiddleKit usage; it causes only this object to be added to the store,
not any dependent objects.
"""
if not object.isInStore():
assert object.key() == None
# Make the store aware of this new object
self.willChange()
self._newObjects.append(object)
object.setStore(self)
if not noRecurse:
# Recursively add referenced objects to the store
object.addReferencedObjectsToStore(self)
# 2000-10-07 ce: Decided not to allow keys for non-persisted objects
# Because the serial num, and therefore the key, will change
# upon saving.
#key = object.key()
#if key is None:
# key = ObjectKey(object, self)
# object.setKey(key)
#self._objects[key] = object
def deleteObject(self, object):
"""
Restrictions: The object must be contained in the store and obviously
you cannot remove it more than once.
"""
# First check if the delete is possible. Then do the actual delete. This avoids partially deleting
# objects only to have an exception halt the process in the middle.
objectsToDel = {}
detaches = []
self._deleteObject(object, objectsToDel,
detaches) # compute objectsToDel and detaches
self.willChange()
# detaches
for obj, attr in detaches:
if not objectsToDel.has_key(id(obj)):
obj.setValueForAttr(attr, None)
# deleted objects
objectsToDel = objectsToDel.values()
self._deletedObjects.extend(objectsToDel)
# remove deleted objects from main list of objects
for obj in objectsToDel:
del self._objects[obj.key()]
def _deleteObject(self, object, objectsToDel, detaches, superobject=None):
"""
Compile the list of objects to be deleted. This is a recursive
method since deleting one object might be deleting others.
object - the object to delete
objectsToDel - a running dictionary of all objects to delete
detaches - a running list of all detaches (eg, obj.attr=None)
superobject - the object that was the cause of this invocation
"""
# Some basic assertions
assert self.hasObject(object)
assert object.key() is not None
v = self._verboseDelete
if v:
if superobject:
cascadeString = 'cascade-'
dueTo = ' due to deletion of %s.%i' % (
superobject.klass().name(), superobject.serialNum())
else:
cascadeString = dueTo = ''
print 'checking %sdelete of %s.%d%s' % (cascadeString,
object.klass().name(),
object.serialNum(), dueTo)
objectsToDel[id(object)] = object
# Deal with all other objects that reference or are referenced by this object. By default, you are not allowed
# to delete an object that has an ObjRef pointing to it. But if the ObjRef has
# onDeleteOther=detach, then that ObjRef attr will be set to None and the delete will be allowed;
# and if onDeleteOther=cascade, then that object will itself be deleted and the delete
# will be allowed.
#
# You _are_ by default allowed to delete an object that points to other objects (by List or ObjRef)
# but if onDeleteSelf=deny it will be disallowed, or if onDeleteSelf=cascade the pointed-to
# objects will themselves be deleted.
# Get the objects/attrs that reference this object
referencingObjectsAndAttrs = object.referencingObjectsAndAttrs()
# Remove from that list anything in the cascaded list
referencingObjectsAndAttrs = [(o, a)
for o, a in referencingObjectsAndAttrs
if not objectsToDel.has_key(id(o))]
# Determine all referenced objects, constructing a list of (attr, referencedObject) tuples.
referencedAttrsAndObjects = []
for attr in object.klass().allDataAttrs():
if isinstance(attr, ObjRefAttr):
obj = object.valueForAttr(attr)
if obj:
referencedAttrsAndObjects.append((attr, obj))
elif isinstance(attr, ListAttr):
for obj in object.valueForAttr(attr):
referencedAttrsAndObjects.append((attr, obj))
# Remove from that list anything in the cascaded list
referencedAttrsAndObjects = [(a, o)
for a, o in referencedAttrsAndObjects
if not objectsToDel.has_key(id(o))]
# Check for onDeleteOther=deny
badObjectsAndAttrs = []
for referencingObject, referencingAttr in referencingObjectsAndAttrs:
onDeleteOther = referencingAttr.get('onDeleteOther', 'deny')
assert onDeleteOther in ('deny', 'detach', 'cascade')
if onDeleteOther == 'deny':
badObjectsAndAttrs.append((referencingObject, referencingAttr))
if badObjectsAndAttrs:
raise DeleteReferencedError(
'You tried to delete an object (%s.%d) that is referenced by other objects with onDeleteOther unspecified or set to deny'
% (object.klass().name(), object.serialNum()), object,
badObjectsAndAttrs)
# Check for onDeleteSelf=deny
badAttrs = []
for referencedAttr, referencedObject in referencedAttrsAndObjects:
onDeleteSelf = referencedAttr.get('onDeleteSelf', 'detach')
assert onDeleteSelf in ['deny', 'detach', 'cascade']
if onDeleteSelf == 'deny':
badAttrs.append(referencedAttr)
if badAttrs:
raise DeleteObjectWithReferencesError(
'You tried to delete an object (%s.%d) that references other objects with onDeleteSelf set to deny'
% (object.klass().name(), object.serialNum()), object,
badAttrs)
# cascade-delete objects with onDeleteOther=cascade
for referencingObject, referencingAttr in referencingObjectsAndAttrs:
onDeleteOther = referencingAttr.get('onDeleteOther', 'deny')
if onDeleteOther == 'cascade':
self._deleteObject(referencingObject, objectsToDel, detaches,
object)
# Check if it's possible to cascade-delete objects with onDeleteSelf=cascade
for referencedAttr, referencedObject in referencedAttrsAndObjects:
onDeleteSelf = referencedAttr.get('onDeleteSelf', 'detach')
if onDeleteSelf == 'cascade':
self._deleteObject(referencedObject, objectsToDel, detaches,
object)
# Detach objects with onDeleteOther=detach
for referencingObject, referencingAttr in referencingObjectsAndAttrs:
onDeleteOther = referencingAttr.get('onDeleteOther', 'deny')
if onDeleteOther == 'detach':
if v:
print 'will set %s.%d.%s to None' % (
referencingObject.klass().name(),
referencingObject.serialNum(), referencingAttr.name())
detaches.append((referencingObject, referencingAttr))
# Detach objects with onDeleteSelf=detach
# This is actually a no-op. There is nothing that needs to be set to zero.
## Changes ##
def hasChangesForCurrentThread(self):
''' return whether the current thread has changes to be committed '''
if self._threaded:
threadid = thread.get_ident()
return self._hasChanges.get(threadid, 0)
else:
return self._hasChanges
def hasChanges(self):
''' return whether any thread has changes to be committed '''
if self._threaded:
return 1 in self._hasChanges.values()
return self._hasChanges
def willChange(self):
if self._threaded:
threadid = thread.get_ident()
self._hasChanges[threadid] = 1
else:
self._hasChanges = 1
def saveAllChanges(self):
""" Commits object changes to the object store by invoking commitInserts(), commitUpdates() and commitDeletions() all of which must by implemented by a concrete subclass. """
self.commitDeletions(allThreads=1)
self.commitInserts(allThreads=1)
self.commitUpdates(allThreads=1)
self._hasChanges = {}
def saveChanges(self):
""" Commits object changes to the object store by invoking commitInserts(), commitUpdates() and commitDeletions() all of which must by implemented by a concrete subclass. """
self.commitDeletions()
self.commitInserts()
self.commitUpdates()
if self._threaded:
self._hasChanges[thread.get_ident()] = 0
else:
self._hasChanges = 0
def commitInserts(self):
""" Invoked by saveChanges() to insert any news objects add since the last save. Subclass responsibility. """
raise AbstractError, self.__class__
def commitUpdates(self):
""" Invoked by saveChanges() to update the persistent store with any changes since the last save. """
raise AbstractError, self.__class__
def commitDeletions(self):
""" Invoked by saveChanges() to delete from the persistent store any objects deleted since the last save. Subclass responsibility. """
raise AbstractError, self.__class__
def revertChanges(self):
""" Discards all insertions and deletions, and restores changed objects to their original values. """
raise NotImplementedError
## Fetching ##
def fetchObject(self, className, serialNum, default=NoDefault):
""" Subclasses should raise UnknownObjectError if an object with the given className and serialNum does not exist, unless a default value was passed in, in which case that value should be returned. """
raise AbstractError, self.__class__
def fetchObjectsOfClass(self, className, isDeep=1):
""" Fetches all objects of a given class. If isDeep is 1, then all subclasses are also returned. """
raise AbstractError, self.__class__
## Other ##
def clear(self):
"""
Clears all objects from the memory of the store. This does not
delete the objects in the persistent backing. This method can
only be invoked if there are no outstanding changes to be
saved. You can check for that with hasChanges().
"""
assert not self.hasChanges()
assert self._newObjects.isEmpty()
assert self._deletedObjects.isEmpty()
assert self._changedObjects.isEmpty()
self._objects = {}
self._newSerialNum = -1
def discardEverything(self):
"""
Discards all cached objects, including any modification
tracking. However, objects in memory will not change state as
a result of this call.
This method is a severe form of clear() and is typically used
only for debugging or production emergencies.
"""
if self._threaded:
self._hasChanges = {}
else:
self._hasChanges = 0
self._objects = {}
self._newObjects.clear()
self._deletedObjects.clear()
self._changedObjects.clear()
self._newSerialNum = -1
## Notifications ##
def objectChanged(self, object):
"""
MiddleObjects must send this message when one of their interesting attributes change, where an attribute is interesting if it's listed in the class model.
This method records the object in a set for later processing when the store's changes are saved.
If you subclass MiddleObject, then you're taken care of.
"""
self.willChange()
self._changedObjects[
object] = object ## @@ 2000-10-06 ce: Should this be keyed by the object.key()? Does it matter?
## Serial numbers ##
def newSerialNum(self):
""" Returns a new serial number for a newly created object. This is a utility methods for objects that have been created, but not yet committed to the persistent store. These serial numbers are actually temporary and replaced upon committal. Also, they are always negative to indicate that they are temporary, whereas serial numbers taken from the persistent store are positive. """
self._newSerialNum -= 1
return self._newSerialNum
## Self utility ##
def _klassForClass(self, aClass):
""" Returns a Klass object for the given class, which may be:
- the Klass object already
- a Python class
- a class name (e.g., string)
Users of this method include the various fetchObjectEtc() methods which take a "class" parameter.
"""
assert aClass is not None
if not isinstance(aClass, BaseKlass):
if type(aClass) is ClassType:
aClass = self._model.klass(aClass.__name__)
elif type(aClass) is StringType:
aClass = self._model.klass(aClass)
else:
raise ValueError, 'Invalid class parameter. Pass a Klass, a name or a Python class. Type of aClass is %s. aClass is %s.' % (
type(aClass), aClass)
return aClass
