def __init__(self, manager):
self.manager = manager
self._new = OrderedDict()
self._deleted = OrderedDict()
self._delete_query = []
self._modified = OrderedDict()
self._queries = []
self._structures = set()
def __init__(self, backend, autocommit = False, query_class = None):
self.backend = getdb(backend)
self.transaction = None
self.autocommit = autocommit
self._new = OrderedDict()
self._deleted = OrderedDict()
self._modified = OrderedDict()
self._loaded = {}
self.query_class = query_class or Query
def __init__(self, meta, session):
self.meta = meta
self.session = session
self.backend.setup_model(meta)
self._new = OrderedDict()
self._deleted = OrderedDict()
self._delete_query = []
self._modified = OrderedDict()
self._loaded = {}
def __init__(self, manager):
self.manager = manager
self._new = OrderedDict()
self._deleted = OrderedDict()
self._delete_query = []
self._modified = OrderedDict()
self._queries = []
self._structures = set()
def get_fields(bases, attrs):
#
fields = []
for name, field in list(attrs.items()):
if isinstance(field, Field):
fields.append((name, attrs.pop(name)))
#
fields = sorted(fields, key=lambda x: x[1].creation_counter)
#
for base in bases:
if hasattr(base, '_meta'):
fields = list(
(name, deepcopy(field))
for name, field in base._meta.dfields.items()) + fields
#
return OrderedDict(fields)
def __init__(self, router):
self.transaction = None
self._models = OrderedDict()
self._router = router
class Session(object):
'''The middleware for persistent operations on the back-end.
It is created via the :meth:`Router.session` method.
.. attribute:: transaction
A :class:`Transaction` instance. Not ``None`` if this :class:`Session`
is in a :ref:`transactional state <transactional-state>`
.. attribute:: router
Instance of the :class:`Router` which created this :class:`Session`.
'''
def __init__(self, router):
self.transaction = None
self._models = OrderedDict()
self._router = router
def __str__(self):
return str(self._router)
def __repr__(self):
return '%s: %s' % (self.__class__.__name__, self._router)
def __iter__(self):
for sm in self._models.values():
yield sm
def __len__(self):
return len(self._models)
@property
def router(self):
return self._router
@property
def dirty(self):
'''The set of instances in this :class:`Session` which have
been modified.'''
return frozenset(chain(*tuple((sm.dirty for sm
in itervalues(self._models)))))
def begin(self, **options):
'''Begin a new :class:`Transaction`. If this :class:`Session`
is already in a :ref:`transactional state <transactional-state>`,
an error will occur. It returns the :attr:`transaction` attribute.
This method is mostly used within a ``with`` statement block::
with session.begin() as t:
t.add(...)
...
which is equivalent to::
t = session.begin()
t.add(...)
...
session.commit()
``options`` parameters are passed to the :class:`Transaction` constructor.
'''
if self.transaction is not None:
raise InvalidTransaction("A transaction is already begun.")
else:
self.transaction = Transaction(self, **options)
return self.transaction
def commit(self):
"""Commit the current :attr:`transaction`.
If no transaction is in progress, this method open one.
Rarely used directly, see the :meth:`begin` method for details on
how to start and close a transaction using the `with` construct.
"""
if self.transaction is None:
self.begin()
return self.transaction.commit()
def query(self, model, **kwargs):
'''Create a new :class:`Query` for *model*.'''
sm = self.model(model)
query_class = sm.manager.query_class or Query
return query_class(sm._meta, self, **kwargs)
def empty(self, model):
'''Returns an empty :class:`Query` for ``model``.'''
return EmptyQuery(self.manager(model)._meta, self)
def update_or_create(self, model, **kwargs):
'''Update or create a new instance of ``model``.
This method can raise an exception if the ``kwargs`` dictionary
contains field data that does not validate.
:param model: a :class:`StdModel`
:param kwargs: dictionary of parameters.
:returns: A two elements tuple containing the instance and a boolean
indicating if the instance was created or not.
'''
backend = self.model(model).backend
return backend.execute(self._update_or_create(model, **kwargs))
def add(self, instance, modified=True, **params):
'''Add an ``instance`` to the session.
If the session is not in a
:ref:`transactional state <transactional-state>`, this operation
commits changes to the back-end server immediately.
:parameter instance: a :class:`Model` instance. It must be registered
with the :attr:`router` which created this :class:`Session`.
:parameter modified: a boolean flag indicating if the instance was
modified.
:return: the ``instance``.
If the instance is persistent (it is already stored in the database),
an updated will be performed, otherwise a new entry will be created
once the :meth:`commit` method is invoked.
'''
sm = self.model(instance)
instance.session = self
o = sm.add(instance, modified=modified, **params)
if modified and not self.transaction:
transaction = self.begin()
return transaction.commit(lambda: o)
else:
return o
def delete(self, instance_or_query):
'''Delete an ``instance`` or a ``query``.
Adds ``instance_or_query`` to this :class:`Session` list
of data to be deleted. If the session is not in a
:ref:`transactional state <transactional-state>`, this operation
commits changes to the backend server immediately.
:parameter instance_or_query: a :class:`Model` instance or
a :class:`Query`.
'''
sm = self.model(instance_or_query)
# not an instance of a Model. Assume it is a query.
if is_query(instance_or_query):
if instance_or_query.session is not self:
raise ValueError('Adding a query generated by another session')
sm._delete_query.append(instance_or_query)
else:
instance_or_query = sm.delete(instance_or_query, self)
if not self.transaction:
transaction = self.begin()
return transaction.commit(
lambda: transaction.deleted.get(sm._meta))
else:
return instance_or_query
def flush(self, model):
'''Completely flush a :class:`Model` from the database. No keys
associated with the model will exists after this operation.'''
return self.model(model).flush()
def clean(self, model):
'''Remove empty keys for a :class:`Model` from the database. No
empty keys associated with the model will exists after this operation.'''
return self.model(model).clean()
def keys(self, model):
'''Retrieve all keys for a *model*.'''
return self.model(model).keys()
def __contains__(self, instance):
sm = self.model(instance, False)
return instance in sm if sm is not None else False
def model(self, model, create=True):
'''Returns the :class:`SessionModel` for ``model`` which
can be :class:`Model`, or a :class:`MetaClass`, or an instance
of :class:`Model`.'''
manager = self.manager(model)
sm = self._models.get(manager)
if sm is None and create:
sm = SessionModel(manager)
self._models[manager] = sm
return sm
def expunge(self, instance=None):
'''Remove ``instance`` from this :class:`Session`. If ``instance``
is not given, it removes all instances from this :class:`Session`.'''
if instance is not None:
sm = self._models.get(instance._meta)
if sm:
return sm.expunge(instance)
else:
self._models.clear()
def manager(self, model):
'''Retrieve the :class:`Manager` for ``model`` which can be any of the
values valid for the :meth:`model` method.'''
try:
return self.router[model]
except KeyError:
meta = getattr(model, '_meta', model)
if meta.type == 'structure':
# this is a structure
if hasattr(model, 'model'):
structure_model = model.model
if structure_model:
return self.manager(structure_model)
else:
manager = self.router.structure(model)
if manager:
return manager
raise InvalidTransaction('"%s" not valid in this session' % meta)
def backends_data(self):
backends = {}
for sm in self:
for backend, data in sm.backends_data(self):
be = backends.get(backend)
if be is None:
backends[backend] = be = []
be.append(data)
return backends.items()
#######################################################################
# INTERNALS
def _update_or_create(self, model, **kwargs):
pkname = model._meta.pkname()
pk = kwargs.pop(pkname, None)
query = self.query(model)
item = None
#
if pk:
# primary key available
items = yield query.filter(pkname=pk).all()
if items:
item = items[0]
else:
kwargs[pkname] = pk
else:
params = {}
rest = {}
fields = model._meta.dfields
for field, value in iteritems(kwargs):
if field in fields and fields[field].index:
params[field] = value
else:
rest[field] = value
if params:
items = yield query.filter(**params).all()
if len(items) == 1:
item = items[0]
kwargs = rest
if item:
if kwargs:
for field, value in iteritems(kwargs):
setattr(item, field, value)
item = yield self.add(item)
yield item, False
#
else:
item = yield self.add(model(**kwargs))
yield item, True
class SessionModel(object):
'''A :class:`SessionModel` is the container of all objects for a given
:class:`Model` in a stdnet :class:`Session`.'''
def __init__(self, manager):
self.manager = manager
self._new = OrderedDict()
self._deleted = OrderedDict()
self._delete_query = []
self._modified = OrderedDict()
self._queries = []
self._structures = set()
def __len__(self):
return (len(self._new) + len(self._modified) + len(self._deleted) +
len(self.commit_structures) + len(self.delete_structures))
def __repr__(self):
return self._meta.__repr__()
__str__ = __repr__
@property
def backend(self):
'''The backend for this :class:`SessionModel`.'''
return self.manager.backend
@property
def read_backend(self):
'''The read-only backend for this :class:`SessionModel`.'''
return self.manager.read_backend
@property
def model(self):
'''The :class:`Model` for this :class:`SessionModel`.'''
return self.manager.model
@property
def _meta(self):
'''The :class:`Metaclass` for this :class:`SessionModel`.'''
return self.manager._meta
@property
def new(self):
'''The set of all new instances within this ``SessionModel``. This
instances will be inserted in the database.'''
return tuple(itervalues(self._new))
@property
def modified(self):
'''The set of all modified instances within this ``Session``. This
instances will.'''
return tuple(itervalues(self._modified))
@property
def deleted(self):
'''The set of all instance pks marked as `deleted` within this
:class:`Session`.'''
return tuple((p.pkvalue() for p in itervalues(self._deleted)))
@property
def dirty(self):
'''The set of all instances which have changed, but not deleted,
within this :class:`SessionModel`.'''
return tuple(self.iterdirty())
def iterdirty(self):
'''Ordered iterator over dirty elements.'''
return iter(chain(itervalues(self._new), itervalues(self._modified)))
def __contains__(self, instance):
iid = instance.get_state().iid
return (iid in self._new or
iid in self._modified or
iid in self._deleted or
instance in self._structures)
def add(self, instance, modified=True, persistent=None,
force_update=False):
'''Add a new instance to this :class:`SessionModel`.
:param modified: Optional flag indicating if the ``instance`` has been
modified. By default its value is ``True``.
:param force_update: if ``instance`` is persistent, it forces an update of the
data rather than a full replacement. This is used by the
:meth:`insert_update_replace` method.
:rtype: The instance added to the session'''
if instance._meta.type == 'structure':
return self._add_structure(instance)
state = instance.get_state()
if state.deleted:
raise ValueError('State is deleted. Cannot add.')
self.pop(state.iid)
pers = persistent if persistent is not None else state.persistent
pkname = instance._meta.pkname()
if not pers:
instance._dbdata.pop(pkname, None) # to make sure it is add action
state = instance.get_state(iid=None)
elif persistent:
instance._dbdata[pkname] = instance.pkvalue()
state = instance.get_state(iid=instance.pkvalue())
else:
action = 'update' if force_update else None
state = instance.get_state(action=action, iid=state.iid)
iid = state.iid
if state.persistent:
if modified:
self._modified[iid] = instance
else:
self._new[iid] = instance
return instance
def delete(self, instance, session):
'''delete an *instance*'''
if instance._meta.type == 'structure':
return self._delete_structure(instance)
inst = self.pop(instance)
instance = inst if inst is not None else instance
if instance is not None:
state = instance.get_state()
if state.persistent:
state.deleted = True
self._deleted[state.iid] = instance
instance.session = session
else:
instance.session = None
return instance
def pop(self, instance):
'''Remove ``instance`` from the :class:`SessionModel`. Instance
could be a :class:`Model` or an id.
:parameter instance: a :class:`Model` or an ``id``.
:rtype: the :class:`Model` removed from session or ``None`` if
it was not in the session.
'''
if isinstance(instance, self.model):
iid = instance.get_state().iid
else:
iid = instance
instance = None
for d in (self._new, self._modified, self._deleted):
if iid in d:
inst = d.pop(iid)
if instance is None:
instance = inst
elif inst is not instance:
raise ValueError('Critical error: %s is duplicated' % iid)
return instance
def expunge(self, instance):
'''Remove *instance* from the :class:`Session`. Instance could be a
:class:`Model` or an id.
:parameter instance: a :class:`Model` or an *id*
:rtype: the :class:`Model` removed from session or ``None`` if
it was not in the session.
'''
instance = self.pop(instance)
instance.session = None
return instance
def post_commit(self, results):
'''\
Process results after a commit.
:parameter results: iterator over :class:`stdnet.instance_session_result`
items.
:rtype: a two elements tuple containing a list of instances saved and
a list of ids of instances deleted.'''
tpy = self._meta.pk_to_python
instances = []
deleted = []
errors = []
# The length of results must be the same as the length of
# all committed instances
for result in results:
if isinstance(result, Exception):
errors.append(result.__class__('Exception while committing %s.'
' %s' % (self._meta, result)))
continue
instance = self.pop(result.iid)
id = tpy(result.id, self.backend)
if result.deleted:
deleted.append(id)
else:
if instance is None:
raise InvalidTransaction('{0} session received id "{1}"\
which is not in the session.'.format(self, result.iid))
setattr(instance, instance._meta.pkname(), id)
instance = self.add(instance,
modified=False,
persistent=result.persistent)
instance.get_state().score = result.score
if instance.get_state().persistent:
instances.append(instance)
return instances, deleted, errors
def flush(self):
'''Completely flush :attr:`model` from the database. No keys
associated with the model will exists after this operation.'''
return self.backend.flush(self._meta)
def clean(self):
'''Remove empty keys for a :attr:`model` from the database. No
empty keys associated with the model will exists after this operation.'''
return self.backend.clean(self._meta)
def keys(self):
'''Retrieve all keys for a :attr:`model`. Uses the
:attr:`Manager.read_backend`.'''
return self.read_backend.model_keys(self._meta)
## INTERNALS
def get_delete_query(self, session):
queries = self._delete_query
deleted = self.deleted
if deleted:
self._deleted.clear()
q = self.manager.query(session)
queries.append(q.filter(**{self._meta.pkname(): deleted}))
if queries:
self._delete_query = []
q = queries[0]
if len(queries) > 1:
q = q.union(*queries[1:])
return q
def backends_data(self, session):
transaction = session.transaction
models = session.router
be = self.backend
rbe = self.read_backend
model = self.model
meta = model._meta
dirty = self.dirty
deletes = self.get_delete_query(session)
has_delete = deletes is not None
structures = self._structures
queries = self._queries
if dirty or has_delete or queries is not None or structures:
if transaction.signal_delete and has_delete:
models.pre_delete.fire(model, instances=deletes,
session=session)
if dirty and transaction.signal_commit:
models.pre_commit.fire(model, instances=dirty,
session=session)
if be == rbe:
yield be, session_data(meta, dirty, deletes, queries,
structures)
else:
if dirty or has_delete or structures:
yield be, session_data(meta, dirty, deletes, (),
structures)
if queries:
yield rbe, session_data(meta, (), (), queries, ())
def _add_structure(self, instance):
instance.action = 'update'
self._structures.add(instance)
return instance
def _delete_structure(self, instance):
instance.action = 'delete'
self._structures.add(instance)
return instance
class Session(object):
'''The manager of persistent operations on the backend data server for
:class:`StdModel` classes.
.. attribute:: backend
the :class:`stdnet.BackendDataServer` instance
.. attribute:: autocommit
When ``True``, the :class:`Session`` does not keep a persistent transaction
running, and will acquire connections from the engine on an as-needed basis,
returning them immediately after their use.
Flushes will begin and commit (or possibly rollback) their own transaction
if no transaction is present. When using this mode, the :meth:`begin`
method may be used to begin a transaction explicitly.
Default: ``False``.
.. attribute:: transaction
A :class:`Transaction` instance. Not ``None`` if this :class:`Session`
is in a transactional state.
.. attribute:: query_class
class for querying. Default is :class:`Query`.
'''
_structures = {}
def __init__(self, backend, autocommit = False, query_class = None):
self.backend = getdb(backend)
self.transaction = None
self.autocommit = autocommit
self._new = OrderedDict()
self._deleted = OrderedDict()
self._modified = OrderedDict()
self._loaded = {}
self.query_class = query_class or Query
@property
def new(self):
"The set of all new instances within this ``Session``"
return frozenset(self._new.values())
@property
def modified(self):
"The set of all modified instances within this ``Session``"
return frozenset(self._modified.values())
@property
def deleted(self):
"The set of all instances marked as 'deleted' within this ``Session``"
return frozenset(self._loaded.values())
@property
def deleted(self):
"The set of all instances marked as 'deleted' within this ``Session``"
return frozenset(self._deleted.values())
def __str__(self):
return str(self.backend)
def __repr__(self):
return '{0}({1})'.format(self.__class__.__name__,self)
def begin(self):
'''Begin a new class:`Transaction`.
If this :class:`Session` is already within a transaction, an error is raised.'''
if self.transaction is not None:
raise InvalidTransaction("A transaction is already begun.")
else:
self.transaction = Transaction(self)
return self.transaction
def query(self, model):
'''Create a new :class:`Query` for *model*.'''
return self.query_class(model._meta, self)
def get_or_create(self, model, **kwargs):
'''Get an instance of *model* from the internal cache (only if the
dictionary *kwargs* is of length 1 and has key given by ``id``) or from the
server. If it the instance is not available, it tries to create one
from the **kwargs** parameters.
:parameter model: a :class:`StdModel`
:parameter kwargs: dictionary of parameters.
:rtype: an instance of two elements tuple containing the instance and a boolean
indicating if the instance was created or not.
'''
try:
res = self.query(model).get(**kwargs)
created = False
except model.DoesNotExist:
res = self.add(model(**kwargs))
created = True
return res,created
def get(self, model, id):
uuid = model.get_uuid(id)
if uuid in self._modified:
return self._modified.get(uuid)
elif uuid in self._deleted:
return self._modified.get(uuid)
def add(self, instance, modified = True):
'''Add an *instance* to the session.
:parameter instance: a class:`StdModel` or a :class:`Structure` instance.
:parameter modified: a boolean flag indictaing if the instance was modified.
'''
state = instance.state()
if state.deleted:
raise ValueError('State is deleted. Cannot add.')
instance.session = self
if state.persistent:
if modified:
self._loaded.pop(state,None)
self._modified[instance] = instance
elif state not in self._modified:
self._loaded[instance] = instance
else:
self._new[instance] = instance
return instance
def delete(self, instance):
self.expunge(instance)
if instance.state().persistent:
self._deleted[instance] = instance
def flush(self, model):
return self.backend.flush(model._meta)
def __contains__(self, instance):
return instance in self._new or state in self._deleted\
or state in self._modified
def __iter__(self):
"""Iterate over all pending or persistent instances within this
Session."""
for v in self._new:
yield v
for m in self._modified:
yield m
for d in self._deleted:
yield d
def commit(self):
"""Flush pending changes and commit the current transaction.
If no transaction is in progress, this method raises an
InvalidRequestError.
By default, the :class:`.Session` also expires all database
loaded state on all ORM-managed attributes after transaction commit.
This so that subsequent operations load the most recent
data from the database. This behavior can be disabled using
the ``expire_on_commit=False`` option to :func:`.sessionmaker` or
the :class:`.Session` constructor.
If a subtransaction is in effect (which occurs when begin() is called
multiple times), the subtransaction will be closed, and the next call
to ``commit()`` will operate on the enclosing transaction.
For a session configured with autocommit=False, a new transaction will
be begun immediately after the commit, but note that the newly begun
transaction does *not* use any connection resources until the first
SQL is actually emitted.
"""
if self.transaction is None:
if not self.autocommit:
self.begin()
else:
raise InvalidTransaction('No transaction was started')
self.transaction.commit()
def expunge(self, instance):
instance._dbdata.pop('state',None)
for d in (self._new,self._modified,self._loaded,self._deleted):
if instance in d:
d.pop(instance)
return True
return False
def server_update(self, instance, id = None):
'''Callback by the :class:`stdnet.BackendDataServer` once the commit is
finished. Remove the deleted instances and updated the modified and new
instances.'''
state = instance.state()
self.expunge(instance)
if not state.deleted:
if id:
instance.id = instance._meta.pk.to_python(id)
instance._dbdata['id'] = instance.id
self.add(instance, False)
return instance
@classmethod
def clearall(cls):
pass
def __init__(self, router):
self.transaction = None
self._models = OrderedDict()
self._router = router
class Session(object):
'''The middleware for persistent operations on the back-end.
It is created via the :meth:`Router.session` method.
.. attribute:: transaction
A :class:`Transaction` instance. Not ``None`` if this :class:`Session`
is in a :ref:`transactional state <transactional-state>`
.. attribute:: router
Instance of the :class:`Router` which created this :class:`Session`.
'''
def __init__(self, router):
self.transaction = None
self._models = OrderedDict()
self._router = router
def __str__(self):
return str(self._router)
def __repr__(self):
return '%s: %s' % (self.__class__.__name__, self._router)
def __iter__(self):
for sm in self._models.values():
yield sm
def __len__(self):
return len(self._models)
@property
def router(self):
return self._router
@property
def dirty(self):
'''The set of instances in this :class:`Session` which have
been modified.'''
return frozenset(
chain(*tuple((sm.dirty for sm in itervalues(self._models)))))
def begin(self, **options):
'''Begin a new :class:`Transaction`. If this :class:`Session`
is already in a :ref:`transactional state <transactional-state>`,
an error will occur. It returns the :attr:`transaction` attribute.
This method is mostly used within a ``with`` statement block::
with session.begin() as t:
t.add(...)
...
which is equivalent to::
t = session.begin()
t.add(...)
...
session.commit()
``options`` parameters are passed to the :class:`Transaction` constructor.
'''
if self.transaction is not None:
raise InvalidTransaction("A transaction is already begun.")
else:
self.transaction = Transaction(self, **options)
return self.transaction
def commit(self):
"""Commit the current :attr:`transaction`.
If no transaction is in progress, this method open one.
Rarely used directly, see the :meth:`begin` method for details on
how to start and close a transaction using the `with` construct.
"""
if self.transaction is None:
self.begin()
return self.transaction.commit()
def query(self, model, **kwargs):
'''Create a new :class:`Query` for *model*.'''
sm = self.model(model)
query_class = sm.manager.query_class or Query
return query_class(sm._meta, self, **kwargs)
def empty(self, model):
'''Returns an empty :class:`Query` for ``model``.'''
return EmptyQuery(self.manager(model)._meta, self)
def update_or_create(self, model, **kwargs):
'''Update or create a new instance of ``model``.
This method can raise an exception if the ``kwargs`` dictionary
contains field data that does not validate.
:param model: a :class:`StdModel`
:param kwargs: dictionary of parameters.
:returns: A two elements tuple containing the instance and a boolean
indicating if the instance was created or not.
'''
backend = self.model(model).backend
return backend.execute(self._update_or_create(model, **kwargs))
def add(self, instance, modified=True, **params):
'''Add an ``instance`` to the session.
If the session is not in a
:ref:`transactional state <transactional-state>`, this operation
commits changes to the back-end server immediately.
:parameter instance: a :class:`Model` instance. It must be registered
with the :attr:`router` which created this :class:`Session`.
:parameter modified: a boolean flag indicating if the instance was
modified.
:return: the ``instance``.
If the instance is persistent (it is already stored in the database),
an updated will be performed, otherwise a new entry will be created
once the :meth:`commit` method is invoked.
'''
sm = self.model(instance)
instance.session = self
o = sm.add(instance, modified=modified, **params)
if modified and not self.transaction:
transaction = self.begin()
return transaction.commit(lambda: o)
else:
return o
def delete(self, instance_or_query):
'''Delete an ``instance`` or a ``query``.
Adds ``instance_or_query`` to this :class:`Session` list
of data to be deleted. If the session is not in a
:ref:`transactional state <transactional-state>`, this operation
commits changes to the backend server immediately.
:parameter instance_or_query: a :class:`Model` instance or
a :class:`Query`.
'''
sm = self.model(instance_or_query)
# not an instance of a Model. Assume it is a query.
if is_query(instance_or_query):
if instance_or_query.session is not self:
raise ValueError('Adding a query generated by another session')
sm._delete_query.append(instance_or_query)
else:
instance_or_query = sm.delete(instance_or_query, self)
if not self.transaction:
transaction = self.begin()
return transaction.commit(
lambda: transaction.deleted.get(sm._meta))
else:
return instance_or_query
def flush(self, model):
'''Completely flush a :class:`Model` from the database. No keys
associated with the model will exists after this operation.'''
return self.model(model).flush()
def clean(self, model):
'''Remove empty keys for a :class:`Model` from the database. No
empty keys associated with the model will exists after this operation.'''
return self.model(model).clean()
def keys(self, model):
'''Retrieve all keys for a *model*.'''
return self.model(model).keys()
def __contains__(self, instance):
sm = self.model(instance, False)
return instance in sm if sm is not None else False
def model(self, model, create=True):
'''Returns the :class:`SessionModel` for ``model`` which
can be :class:`Model`, or a :class:`MetaClass`, or an instance
of :class:`Model`.'''
manager = self.manager(model)
sm = self._models.get(manager)
if sm is None and create:
sm = SessionModel(manager)
self._models[manager] = sm
return sm
def expunge(self, instance=None):
'''Remove ``instance`` from this :class:`Session`. If ``instance``
is not given, it removes all instances from this :class:`Session`.'''
if instance is not None:
sm = self._models.get(instance._meta)
if sm:
return sm.expunge(instance)
else:
self._models.clear()
def manager(self, model):
'''Retrieve the :class:`Manager` for ``model`` which can be any of the
values valid for the :meth:`model` method.'''
try:
return self.router[model]
except KeyError:
meta = getattr(model, '_meta', model)
if meta.type == 'structure':
# this is a structure
if hasattr(model, 'model'):
structure_model = model.model
if structure_model:
return self.manager(structure_model)
else:
manager = self.router.structure(model)
if manager:
return manager
raise InvalidTransaction('"%s" not valid in this session' % meta)
def backends_data(self):
backends = {}
for sm in self:
for backend, data in sm.backends_data(self):
be = backends.get(backend)
if be is None:
backends[backend] = be = []
be.append(data)
return backends.items()
#######################################################################
# INTERNALS
def _update_or_create(self, model, **kwargs):
pkname = model._meta.pkname()
pk = kwargs.pop(pkname, None)
query = self.query(model)
item = None
#
if pk:
# primary key available
items = yield query.filter(pkname=pk).all()
if items:
item = items[0]
else:
kwargs[pkname] = pk
else:
params = {}
rest = {}
fields = model._meta.dfields
for field, value in iteritems(kwargs):
if field in fields and fields[field].index:
params[field] = value
else:
rest[field] = value
if params:
items = yield query.filter(**params).all()
if len(items) == 1:
item = items[0]
kwargs = rest
if item:
if kwargs:
for field, value in iteritems(kwargs):
setattr(item, field, value)
item = yield self.add(item)
yield item, False
#
else:
item = yield self.add(model(**kwargs))
yield item, True
class SessionModel(object):
'''A :class:`SessionModel` is the container of all objects for a given
:class:`Model` in a stdnet :class:`Session`.'''
def __init__(self, manager):
self.manager = manager
self._new = OrderedDict()
self._deleted = OrderedDict()
self._delete_query = []
self._modified = OrderedDict()
self._queries = []
self._structures = set()
def __len__(self):
return (len(self._new) + len(self._modified) + len(self._deleted) +
len(self.commit_structures) + len(self.delete_structures))
def __repr__(self):
return self._meta.__repr__()
__str__ = __repr__
@property
def backend(self):
'''The backend for this :class:`SessionModel`.'''
return self.manager.backend
@property
def read_backend(self):
'''The read-only backend for this :class:`SessionModel`.'''
return self.manager.read_backend
@property
def model(self):
'''The :class:`Model` for this :class:`SessionModel`.'''
return self.manager.model
@property
def _meta(self):
'''The :class:`Metaclass` for this :class:`SessionModel`.'''
return self.manager._meta
@property
def new(self):
'''The set of all new instances within this ``SessionModel``. This
instances will be inserted in the database.'''
return tuple(itervalues(self._new))
@property
def modified(self):
'''The set of all modified instances within this ``Session``. This
instances will.'''
return tuple(itervalues(self._modified))
@property
def deleted(self):
'''The set of all instance pks marked as `deleted` within this
:class:`Session`.'''
return tuple((p.pkvalue() for p in itervalues(self._deleted)))
@property
def dirty(self):
'''The set of all instances which have changed, but not deleted,
within this :class:`SessionModel`.'''
return tuple(self.iterdirty())
def iterdirty(self):
'''Ordered iterator over dirty elements.'''
return iter(chain(itervalues(self._new), itervalues(self._modified)))
def __contains__(self, instance):
iid = instance.get_state().iid
return (iid in self._new or iid in self._modified
or iid in self._deleted or instance in self._structures)
def add(self,
instance,
modified=True,
persistent=None,
force_update=False):
'''Add a new instance to this :class:`SessionModel`.
:param modified: Optional flag indicating if the ``instance`` has been
modified. By default its value is ``True``.
:param force_update: if ``instance`` is persistent, it forces an update of the
data rather than a full replacement. This is used by the
:meth:`insert_update_replace` method.
:rtype: The instance added to the session'''
if instance._meta.type == 'structure':
return self._add_structure(instance)
state = instance.get_state()
if state.deleted:
raise ValueError('State is deleted. Cannot add.')
self.pop(state.iid)
pers = persistent if persistent is not None else state.persistent
pkname = instance._meta.pkname()
if not pers:
instance._dbdata.pop(pkname, None) # to make sure it is add action
state = instance.get_state(iid=None)
elif persistent:
instance._dbdata[pkname] = instance.pkvalue()
state = instance.get_state(iid=instance.pkvalue())
else:
action = 'update' if force_update else None
state = instance.get_state(action=action, iid=state.iid)
iid = state.iid
if state.persistent:
if modified:
self._modified[iid] = instance
else:
self._new[iid] = instance
return instance
def delete(self, instance, session):
'''delete an *instance*'''
if instance._meta.type == 'structure':
return self._delete_structure(instance)
inst = self.pop(instance)
instance = inst if inst is not None else instance
if instance is not None:
state = instance.get_state()
if state.persistent:
state.deleted = True
self._deleted[state.iid] = instance
instance.session = session
else:
instance.session = None
return instance
def pop(self, instance):
'''Remove ``instance`` from the :class:`SessionModel`. Instance
could be a :class:`Model` or an id.
:parameter instance: a :class:`Model` or an ``id``.
:rtype: the :class:`Model` removed from session or ``None`` if
it was not in the session.
'''
if isinstance(instance, self.model):
iid = instance.get_state().iid
else:
iid = instance
instance = None
for d in (self._new, self._modified, self._deleted):
if iid in d:
inst = d.pop(iid)
if instance is None:
instance = inst
elif inst is not instance:
raise ValueError('Critical error: %s is duplicated' % iid)
return instance
def expunge(self, instance):
'''Remove *instance* from the :class:`Session`. Instance could be a
:class:`Model` or an id.
:parameter instance: a :class:`Model` or an *id*
:rtype: the :class:`Model` removed from session or ``None`` if
it was not in the session.
'''
instance = self.pop(instance)
instance.session = None
return instance
def post_commit(self, results):
'''\
Process results after a commit.
:parameter results: iterator over :class:`stdnet.instance_session_result`
items.
:rtype: a two elements tuple containing a list of instances saved and
a list of ids of instances deleted.'''
tpy = self._meta.pk_to_python
instances = []
deleted = []
errors = []
# The length of results must be the same as the length of
# all committed instances
for result in results:
if isinstance(result, Exception):
errors.append(
result.__class__('Exception while committing %s.'
' %s' % (self._meta, result)))
continue
instance = self.pop(result.iid)
id = tpy(result.id, self.backend)
if result.deleted:
deleted.append(id)
else:
if instance is None:
raise InvalidTransaction('{0} session received id "{1}"\
which is not in the session.'.format(self, result.iid))
setattr(instance, instance._meta.pkname(), id)
instance = self.add(instance,
modified=False,
persistent=result.persistent)
instance.get_state().score = result.score
if instance.get_state().persistent:
instances.append(instance)
return instances, deleted, errors
def flush(self):
'''Completely flush :attr:`model` from the database. No keys
associated with the model will exists after this operation.'''
return self.backend.flush(self._meta)
def clean(self):
'''Remove empty keys for a :attr:`model` from the database. No
empty keys associated with the model will exists after this operation.'''
return self.backend.clean(self._meta)
def keys(self):
'''Retrieve all keys for a :attr:`model`. Uses the
:attr:`Manager.read_backend`.'''
return self.read_backend.model_keys(self._meta)
## INTERNALS
def get_delete_query(self, session):
queries = self._delete_query
deleted = self.deleted
if deleted:
self._deleted.clear()
q = self.manager.query(session)
queries.append(q.filter(**{self._meta.pkname(): deleted}))
if queries:
self._delete_query = []
q = queries[0]
if len(queries) > 1:
q = q.union(*queries[1:])
return q
def backends_data(self, session):
transaction = session.transaction
models = session.router
be = self.backend
rbe = self.read_backend
model = self.model
meta = model._meta
dirty = self.dirty
deletes = self.get_delete_query(session)
has_delete = deletes is not None
structures = self._structures
queries = self._queries
if dirty or has_delete or queries is not None or structures:
if transaction.signal_delete and has_delete:
models.pre_delete.fire(model,
instances=deletes,
session=session)
if dirty and transaction.signal_commit:
models.pre_commit.fire(model, instances=dirty, session=session)
if be == rbe:
yield be, session_data(meta, dirty, deletes, queries,
structures)
else:
if dirty or has_delete or structures:
yield be, session_data(meta, dirty, deletes, (),
structures)
if queries:
yield rbe, session_data(meta, (), (), queries, ())
def _add_structure(self, instance):
instance.action = 'update'
self._structures.add(instance)
return instance
def _delete_structure(self, instance):
instance.action = 'delete'
self._structures.add(instance)
return instance
class SessionModel(object):
'''A :class:`SessionModel` is the container of all objects for a given
:class:`Model` in a stdnet :class:`Session`.'''
def __init__(self, meta, session):
self.meta = meta
self.session = session
self.backend.setup_model(meta)
self._new = OrderedDict()
self._deleted = OrderedDict()
self._delete_query = []
self._modified = OrderedDict()
self._loaded = {}
def __len__(self):
return len(self._new) + len(self._modified) + len(self._deleted) +\
len(self._loaded)
def __repr__(self):
return self.meta.__repr__()
__str__ = __repr__
def __iter__(self):
"""Iterate over all pending or persistent instances within this
Session model."""
return iter(self.all())
def all(self):
return chain(self._new,self._modified,self._loaded,self._deleted)
@property
def backend(self):
return self.session.backend
@property
def model(self):
return self.meta.model
@property
def new(self):
"The set of all modified instances within this ``Session``"
return frozenset(itervalues(self._new))
@property
def modified(self):
"The set of all modified instances within this ``Session``"
return frozenset(itervalues(self._modified))
@property
def loaded(self):
'''The set of all unmodified, but not deleted, instances within this
:class:`Session`.'''
return frozenset(itervalues(self._loaded))
@property
def deleted(self):
'''The set of all instances marked as 'deleted' within this
:class:`Session`.'''
return frozenset(itervalues(self._deleted))
@property
def dirty(self):
'''The set of all instances which have changed, but not deleted,
within this :class:`Session`.'''
return frozenset(self.iterdirty())
def iterdirty(self):
'''Ordered iterator over dirty elements.'''
return iter(chain(itervalues(self._new), itervalues(self._modified)))
def __contains__(self, instance):
iid = instance.state().iid
return iid in self._new or\
iid in self._modified or\
iid in self._deleted or\
iid in self._loaded
def get(self, id):
if id in self._modified:
return self._modified.get(id)
elif id in self._deleted:
return self._deleted.get(id)
elif id in self._loaded:
return self._loaded.get(id)
def add(self, instance, modified=True, persistent=None):
'''Add a new instance to this :class:`SessionModel`.
:modified: Optional flag indicating if the *instance* has been modified. By
default its value is ``True``.
:rtype: The instance added to the session'''
state = instance.state()
if state.deleted:
raise ValueError('State is deleted. Cannot add.')
self.pop(state.iid)
persistent = persistent if persistent is not None else state.persistent
pkname = instance._meta.pkname()
if persistent:
instance._dbdata[pkname] = instance.pkvalue()
else:
instance._dbdata.pop(pkname, None)
state = instance.state(update=True)
iid = state.iid
if state.persistent:
if modified:
self._modified[iid] = instance
else:
self._loaded[iid] = instance
else:
self._new[iid] = instance
return instance
def delete(self, instance, session):
'''delete an *instance*'''
inst = self.pop(instance)
instance = inst if inst is not None else instance
if instance is not None:
state = instance.state()
if state.persistent:
state.deleted = True
self._deleted[state.iid] = instance
instance.session = session
else:
instance.session = None
return instance
def pop(self, instance):
'''Remove *instance* from the :class:`Session`. Instance could be a
:class:`Model` or an id.
:parameter instance: a :class:`Model` or an *id*
:rtype: the :class:`Model` removed from session or ``None`` if
it was not in the session.
'''
if isinstance(instance,self.meta.model):
iid = instance.state().iid
else:
iid = instance
instance = None
for d in (self._new, self._modified, self._loaded, self._deleted):
if iid in d:
inst = d.pop(iid)
if instance is None:
instance = inst
elif inst is not instance:
raise ValueError(\
'Critical error. Instance {0} is duplicated'.format(iid))
return instance
def expunge(self, instance):
'''Remove *instance* from the :class:`Session`. Instance could be a
:class:`Model` or an id.
:parameter instance: a :class:`Model` or an *id*
:rtype: the :class:`Model` removed from session or ``None`` if
it was not in the session.
'''
instance = self.pop(instance)
instance.session = None
return instance
def get_delete_query(self, **kwargs):
queries = self._delete_query
if queries:
q = queries[0]
if len(queries) > 1:
q = q.union(*queries[1:])
return q.backend_query(**kwargs)
def query(self):
return self.session.query(self.model)
def pre_commit(self, transaction):
d = self.deleted
if d:
self._deleted.clear()
if self.model._model_type == 'object':
q = self.query().filter(id__in = d)
self._delete_query.append(q)
else:
self._delete_query.extend(d)
if transaction.signal_delete:
pre_delete.send(self.model, instances=self._delete_query,
transaction=transaction)
dirty = tuple(self.iterdirty())
if dirty and transaction.signal_commit:
pre_commit.send(self.model, instances=dirty,
transaction=transaction)
return len(self._delete_query) + len(dirty)
def post_commit(self, results):
'''\
Process results after a commit.
:parameter results: iterator over :class:`stdnet.instance_session_result`
items.
:rtype: a two elements tuple containing a list of instances saved and
a list of ids of instances deleted.'''
tpy = self.meta.pk_to_python
instances = []
deleted = []
errors = []
# The length of results must be the same as the length of
# all committed instances
for result in results:
if isinstance(result, Exception):
errors.append(result.__class__(
'Exception while commiting {0}. {1}'.format(self.meta, result)))
continue
instance = self.pop(result.iid)
id = tpy(result.id)
if result.deleted:
deleted.append(id)
else:
if instance is None:
raise InvalidTransaction('{0} session received id "{1}"\
which is not in the session.'.format(self, result.iid))
setattr(instance, instance._meta.pkname(), id)
instance = self.add(instance,
modified=False,
persistent=result.persistent)
instance.state().score = result.score
if instance.state().persistent:
instances.append(instance)
return instances, deleted, errors
def __init__(self, backend, query_class=None):
self.backend = getdb(backend)
self.transaction = None
self._models = OrderedDict()
self.query_class = query_class or Query
class Session(object):
'''The manager of persistent operations on the backend data server for
:class:`StdModel` classes.
.. attribute:: backend
the :class:`stdnet.BackendDataServer` instance
.. attribute:: transaction
A :class:`Transaction` instance. Not ``None`` if this :class:`Session`
is in a transactional state.
.. attribute:: query_class
class for querying. Default is :class:`Query`.
'''
_structures = {}
def __init__(self, backend, query_class=None):
self.backend = getdb(backend)
self.transaction = None
self._models = OrderedDict()
self.query_class = query_class or Query
def __str__(self):
return str(self.backend)
def __repr__(self):
return '{0}({1})'.format(self.__class__.__name__,self)
def __iter__(self):
for sm in self._models.values():
yield sm
def __len__(self):
return len(self._models)
@property
def dirty(self):
'''set of all changed instances in the session'''
return frozenset(chain(*tuple((sm.dirty for sm\
in itervalues(self._models)))))
def session(self):
'''Create a new session from this :class:`Session`'''
return self.__class__(self.backend,self.query_class)
def model(self, meta):
if hasattr(meta, '_meta'):
meta = meta._meta
sm = self._models.get(meta)
if sm is None:
if meta.model._model_type == 'structure':
sm = SessionStructure(meta, self)
else:
sm = SessionModel(meta, self)
self._models[meta] = sm
return sm
def expunge(self, instance = None):
if instance is not None:
sm = self._models.get(instance._meta)
if sm:
return sm.expunge(instance)
else:
self._models.clear()
def begin(self, **options):
'''Begin a new :class:`Transaction`.
If this :class:`Session` is already within a transaction, an error is raised.
It returns the :attr:`transaction` attribute. It can be used in a `with`
construct::
with session.begin() as t:
t.add(...
...
which is equivalent to::
t = session.begin()
t.add(...
...
session.commit()
`options` parameter are passed to the :class:`Transaction` constructor.
'''
if self.transaction is not None:
raise InvalidTransaction("A transaction is already begun.")
else:
self.transaction = Transaction(self, **options)
return self.transaction
def commit(self):
"""Commit the current :attr:`transaction`. If no transaction is in
progress, this method open one. Rarely used directly, see the :meth:`begin`
method for details on how to start and close a transaction using the `with`
construct."""
if self.transaction is None:
self.begin()
return self.transaction.commit()
def query(self, model, query_class=None, **kwargs):
'''Create a new :class:`Query` for *model*.'''
query_class = query_class or self.query_class
return query_class(model._meta, self, **kwargs)
def empty(self, model):
return EmptyQuery(model._meta, self)
def get_or_create(self, model, **kwargs):
'''Get an instance of *model* from the internal cache (only if the
dictionary *kwargs* is of length 1 and has key given by ``id``) or from the
server. If it the instance is not available, it tries to create one
from the **kwargs** parameters.
:parameter model: a :class:`StdModel`
:parameter kwargs: dictionary of parameters.
:rtype: an instance of two elements tuple containing the instance and a boolean
indicating if the instance was created or not.
'''
try:
res = self.query(model).get(**kwargs)
created = False
except model.DoesNotExist:
res = self.add(model(**kwargs))
created = True
return res,created
def get(self, model, id):
sm = self._models.get(model._meta)
if sm:
return sm.get(id)
@commit_element_when_no_transaction
def add(self, instance, modified=True):
'''Add an *instance* to the session.
:parameter instance: a class:`StdModel` or a :class:`Structure` instance.
:parameter modified: a boolean flag indicating if the instance was modified.
'''
sm = self.model(instance._meta)
instance.session = self
return sm.add(instance, modified)
@commit_element_when_no_transaction
def delete(self, instance, **kwargs):
'''Add an *instance* to the session instances to be deleted.
:parameter instance: a class:`StdModel` or a :class:`Structure` instance.
'''
sm = self.model(instance._meta)
# not an instance of a Model. Assume it is a query.
if is_query(instance):
if instance.session is not self:
raise ValueError('Adding a query generated by another session')
sm._delete_query.append(instance)
return instance
else:
return sm.delete(instance, self)
def flush(self, model):
'''Completely flush a :class:`Model` from the database. No keys
associated with the model will exists after this operation.'''
return self.backend.flush(model._meta)
def clean(self, model):
'''Remove empty keys for a :class:`Model` from the database. No
empty keys associated with the model will exists after this operation.'''
return self.backend.clean(model._meta)
def keys(self, model):
'''Retrieve all keys for a *model*.'''
return self.backend.model_keys(model._meta)
def __contains__(self, instance):
sm = self._models.get(instance._meta)
return instance in sm if sm is not None else False
def structure(self, instance):
'''Return a :class:`stdnet.BackendStructure` for a given
:class:`Structure` *instance*.'''
return self.backend.structure(instance)
@classmethod
def clearall(cls):
pass
