Merge pull request #231 from quantus/feature/multi-column-observer
Feature/multi column observer
This commit is contained in:
Konsta Vesterinen
GitHub
commit
8fc4fe5550
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@ -148,6 +148,29 @@ Category has many Products.
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session.commit()
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catalog.product_count # 1
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Observing multiple columns
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-----------------------
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You can also observe multiple columns by spesifying all the observable columns
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in the decorator.
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::
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class Order(Base):
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__tablename__ = 'order'
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id = sa.Column(sa.Integer, primary_key=True)
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unit_price = sa.Column(sa.Integer)
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amount = sa.Column(sa.Integer)
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total_price = sa.Column(sa.Integer)
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@observes('amount', 'unit_price')
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def total_price_observer(self, amount, unit_price):
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self.total_price = amount * unit_price
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"""
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import itertools
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from collections import defaultdict, Iterable, namedtuple
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@ -158,7 +181,7 @@ from .functions import getdotattr, has_changes
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from .path import AttrPath
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from .utils import is_sequence
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Callback = namedtuple('Callback', ['func', 'path', 'backref', 'fullpath'])
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Callback = namedtuple('Callback', ['func', 'backref', 'fullpath'])
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class PropertyObserver(object):
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@ -208,32 +231,33 @@ class PropertyObserver(object):
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)
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def gather_paths(self):
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for class_, callbacks in self.generator_registry.items():
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for callback in callbacks:
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path = AttrPath(class_, callback.__observes__)
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for class_, generators in self.generator_registry.items():
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for callback in generators:
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full_paths = []
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for call_path in callback.__observes__:
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full_paths.append(AttrPath(class_, call_path))
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self.callback_map[class_].append(
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Callback(
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func=callback,
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path=path,
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backref=None,
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fullpath=path
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)
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)
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for index in range(len(path)):
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i = index + 1
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prop = path[index].property
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if isinstance(prop, sa.orm.RelationshipProperty):
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prop_class = path[index].property.mapper.class_
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self.callback_map[prop_class].append(
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Callback(
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func=callback,
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path=path[i:],
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backref=~ (path[:i]),
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fullpath=path
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)
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for path in full_paths:
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self.callback_map[class_].append(
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Callback(
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func=callback,
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backref=None,
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fullpath=full_paths
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)
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)
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for index in range(len(path)):
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i = index + 1
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prop = path[index].property
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if isinstance(prop, sa.orm.RelationshipProperty):
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prop_class = path[index].property.mapper.class_
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self.callback_map[prop_class].append(
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Callback(
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func=callback,
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backref=~ (path[:i]),
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fullpath=full_paths
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)
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)
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def gather_callback_args(self, obj, callbacks):
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for callback in callbacks:
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@ -252,18 +276,19 @@ class PropertyObserver(object):
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def get_callback_args(self, root_obj, callback):
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session = sa.orm.object_session(root_obj)
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objects = getdotattr(
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objects = [getdotattr(
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root_obj,
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callback.fullpath,
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path,
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lambda obj: obj not in session.deleted
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)
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path = str(callback.fullpath)
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if '.' in path or has_changes(root_obj, path):
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return (
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root_obj,
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callback.func,
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objects
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)
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) for path in callback.fullpath]
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paths = [str(path) for path in callback.fullpath]
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for path in paths:
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if '.' in path or has_changes(root_obj, path):
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return (
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root_obj,
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callback.func,
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objects
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)
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def iterate_objects_and_callbacks(self, session):
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objs = itertools.chain(session.new, session.dirty, session.deleted)
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@ -277,21 +302,25 @@ class PropertyObserver(object):
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for obj, callbacks in self.iterate_objects_and_callbacks(session):
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args = self.gather_callback_args(obj, callbacks)
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for (root_obj, func, objects) in args:
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if is_sequence(objects):
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callback_args[root_obj][func] = (
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callback_args[root_obj][func] | set(objects)
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)
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else:
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callback_args[root_obj][func] = objects
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if not callback_args[root_obj][func]:
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callback_args[root_obj][func] = {}
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for i, object_ in enumerate(objects):
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if is_sequence(object_):
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callback_args[root_obj][func][i] = (
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callback_args[root_obj][func].get(i, set()) |
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set(object_)
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)
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else:
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callback_args[root_obj][func][i] = object_
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for root_obj, callback_objs in callback_args.items():
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for callback, objs in callback_objs.items():
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callback(root_obj, objs)
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callback(root_obj, *[objs[i] for i in range(len(objs))])
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observer = PropertyObserver()
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def observes(path, observer=observer):
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def observes(*paths, **observer_kw):
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"""
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Mark method as property observer for the given property path. Inside
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transaction observer gathers all changes made in given property path and
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@ -327,14 +356,17 @@ def observes(path, observer=observer):
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.. versionadded: 0.28.0
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:param path: Dot-notated property path, eg. 'categories.products.price'
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:param observer: :meth:`PropertyObserver` object
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:param *paths: One or more dot-notated property paths, eg.
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'categories.products.price'
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:param **observer: A dictionary where value for key 'observer' contains
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:meth:`PropertyObserver` object
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"""
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observer.register_listeners()
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observer_ = observer_kw.pop('observer', observer)
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observer_.register_listeners()
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def wraps(func):
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def wrapper(self, *args, **kwargs):
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return func(self, *args, **kwargs)
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wrapper.__observes__ = path
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wrapper.__observes__ = paths
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return wrapper
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return wraps
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@ -58,3 +58,75 @@ class TestObservesForColumnWithoutActualChanges(object):
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product.price = 500
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session.commit()
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assert str(e.value) == 'Trying to change price'
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@pytest.mark.usefixtures('postgresql_dsn')
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class TestObservesForMultipleColumns(object):
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@pytest.fixture
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def Order(self, Base):
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class Order(Base):
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__tablename__ = 'order'
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id = sa.Column(sa.Integer, primary_key=True)
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unit_price = sa.Column(sa.Integer)
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amount = sa.Column(sa.Integer)
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total_price = sa.Column(sa.Integer)
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@observes('amount', 'unit_price')
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def total_price_observer(self, amount, unit_price):
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self.total_price = amount * unit_price
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return Order
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@pytest.fixture
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def init_models(self, Order):
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pass
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def test_only_notifies_observer_on_actual_changes(self, session, Order):
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order = Order()
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order.amount = 2
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order.unit_price = 10
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session.add(order)
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session.flush()
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order.amount = 1
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session.flush()
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assert order.total_price == 10
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order.unit_price = 100
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session.flush()
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assert order.total_price == 100
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@pytest.mark.usefixtures('postgresql_dsn')
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class TestObservesForMultipleColumnsFiresOnlyOnce(object):
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@pytest.fixture
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def Order(self, Base):
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class Order(Base):
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__tablename__ = 'order'
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id = sa.Column(sa.Integer, primary_key=True)
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unit_price = sa.Column(sa.Integer)
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amount = sa.Column(sa.Integer)
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@observes('amount', 'unit_price')
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def total_price_observer(self, amount, unit_price):
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self.call_count = self.call_count + 1
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return Order
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@pytest.fixture
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def init_models(self, Order):
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pass
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def test_only_notifies_observer_on_actual_changes(self, session, Order):
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order = Order()
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order.amount = 2
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order.unit_price = 10
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order.call_count = 0
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session.add(order)
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session.flush()
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assert order.call_count == 1
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order.amount = 1
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order.unit_price = 100
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session.flush()
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assert order.call_count == 2
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