diff options
Diffstat (limited to 'lib/sqlalchemy/orm/attributes.py')
| -rw-r--r-- | lib/sqlalchemy/orm/attributes.py | 101 |
1 files changed, 61 insertions, 40 deletions
diff --git a/lib/sqlalchemy/orm/attributes.py b/lib/sqlalchemy/orm/attributes.py index c084db8a8..ba262266b 100644 --- a/lib/sqlalchemy/orm/attributes.py +++ b/lib/sqlalchemy/orm/attributes.py @@ -28,6 +28,12 @@ ATTR_EMPTY = util.symbol('ATTR_EMPTY') NO_VALUE = util.symbol('NO_VALUE') NEVER_SET = util.symbol('NEVER_SET') +PASSIVE_RETURN_NEVER_SET = util.symbol('PASSIVE_RETURN_NEVER_SET' +"""Symbol indicating that a 'default' value, i.e. None or blank +collection, should not be assigned to an attribute when a get() +is performed and no value was present. NEVER_SET is returned +instead. +""") PASSIVE_NO_INITIALIZE = util.symbol('PASSIVE_NO_INITIALIZE', """Symbol indicating that loader callables should @@ -429,8 +435,11 @@ class AttributeImpl(object): elif value is not ATTR_EMPTY: return self.set_committed_value(state, dict_, value) - # Return a new, empty value - return self.initialize(state, dict_) + if passive is PASSIVE_RETURN_NEVER_SET: + return NEVER_SET + else: + # Return a new, empty value + return self.initialize(state, dict_) def append(self, state, dict_, value, initiator, passive=PASSIVE_OFF): self.set(state, dict_, value, initiator, passive=passive) @@ -471,7 +480,7 @@ class ScalarAttributeImpl(AttributeImpl): # TODO: catch key errors, convert to attributeerror? if self.dispatch._active_history: - old = self.get(state, dict_) + old = self.get(state, dict_, PASSIVE_RETURN_NEVER_SET) else: old = dict_.get(self.key, NO_VALUE) @@ -489,7 +498,7 @@ class ScalarAttributeImpl(AttributeImpl): return if self.dispatch._active_history: - old = self.get(state, dict_) + old = self.get(state, dict_, PASSIVE_RETURN_NEVER_SET) else: old = dict_.get(self.key, NO_VALUE) @@ -599,6 +608,8 @@ class ScalarObjectAttributeImpl(ScalarAttributeImpl): if self.key in dict_: return History.from_object_attribute(self, state, dict_[self.key]) else: + if passive is PASSIVE_OFF: + passive = PASSIVE_RETURN_NEVER_SET current = self.get(state, dict_, passive=passive) if current is PASSIVE_NO_RESULT: return HISTORY_BLANK @@ -968,6 +979,11 @@ def backref_listeners(attribute, key, uselist): emit_backref_from_collection_remove_event, retval=True, raw=True) +_NO_HISTORY = util.symbol('NO_HISTORY') +_NO_STATE_SYMBOLS = frozenset([ + id(PASSIVE_NO_RESULT), + id(NO_VALUE), + id(NEVER_SET)]) class History(tuple): """A 3-tuple of added, unchanged and deleted values, representing the changes which have occurred on an instrumented @@ -1035,73 +1051,78 @@ class History(tuple): def as_state(self): return History( - [(c is not None and c is not PASSIVE_NO_RESULT) + [(c is not None) and instance_state(c) or None for c in self.added], - [(c is not None and c is not PASSIVE_NO_RESULT) + [(c is not None) and instance_state(c) or None for c in self.unchanged], - [(c is not None and c is not PASSIVE_NO_RESULT) + [(c is not None) and instance_state(c) or None for c in self.deleted], ) @classmethod def from_scalar_attribute(cls, attribute, state, current): - original = state.committed_state.get(attribute.key, NEVER_SET) - if current is NO_VALUE: - if (original is not None and - original is not NEVER_SET and - original is not NO_VALUE): - deleted = [original] + original = state.committed_state.get(attribute.key, _NO_HISTORY) + + if original is _NO_HISTORY: + if current is NO_VALUE: + return cls((), (), ()) else: - deleted = () - return cls((), (), deleted) - elif original is NO_VALUE: - return cls([current], (), ()) - elif (original is NEVER_SET or - attribute.is_equal(current, original) is True): - # dont let ClauseElement expressions here trip things up + return cls((), [current], ()) + # dont let ClauseElement expressions here trip things up + elif attribute.is_equal(current, original) is True: return cls((), [current], ()) else: - if original is not None: + # current convention on native scalars is to not + # include information + # about missing previous value in "deleted", but + # we do include None, which helps in some primary + # key situations + if id(original) in _NO_STATE_SYMBOLS: + deleted = () + else: deleted = [original] + if current is NO_VALUE: + return cls((), (), deleted) else: - deleted = () - return cls([current], (), deleted) + return cls([current], (), deleted) @classmethod def from_object_attribute(cls, attribute, state, current): - original = state.committed_state.get(attribute.key, NEVER_SET) + original = state.committed_state.get(attribute.key, _NO_HISTORY) - if current is NO_VALUE: - if (original is not None and - original is not NEVER_SET and - original is not NO_VALUE): - deleted = [original] + if original is _NO_HISTORY: + if current is NO_VALUE or current is NEVER_SET: + return cls((), (), ()) else: - deleted = () - return cls((), (), deleted) - elif original is NO_VALUE: - return cls([current], (), ()) - elif (original is NEVER_SET or - current is original): + return cls((), [current], ()) + elif current is original: return cls((), [current], ()) else: - if original is not None: + # current convention on related objects is to not + # include information + # about missing previous value in "deleted", and + # to also not include None - the dependency.py rules + # ignore the None in any case. + if id(original) in _NO_STATE_SYMBOLS or original is None: + deleted = () + else: deleted = [original] + if current is NO_VALUE or current is NEVER_SET: + return cls((), (), deleted) else: - deleted = () - return cls([current], (), deleted) + return cls([current], (), deleted) @classmethod def from_collection(cls, attribute, state, current): - original = state.committed_state.get(attribute.key, NEVER_SET) + original = state.committed_state.get(attribute.key, _NO_HISTORY) current = getattr(current, '_sa_adapter') if original is NO_VALUE: return cls(list(current), (), ()) - elif original is NEVER_SET: + elif original is _NO_HISTORY: return cls((), list(current), ()) else: current_states = [(instance_state(c), c) for c in current] |