Hello everyone.
I have a class that uses a "custom" column to store a list of strings.
The column is saved in the database using a comma sepparated string.
When it's loaded into an instance, it "becomes" a list:
class Keyword(declarativeBase):
__tablename__ = "keywords"
_id = Column("id", Integer, primary_key=True)
_values = column_property(Column("values",
CharSeparatedStrings.CharSeparatedStrings()),
extension=ValuesAttributeExtension.ValuesAttributeExtension(),
active_history=True)
I want to use an extension to check the items that have been
deleted/modified in that list. That's why I'm wrapping the Column in a
column_property.
When I put a bunch of checkpoints in the "ValueAttributeExtension",
the value that is going to be set is always an empty list. The
oldvalue works fine, though:
class ValuesAttributeExtension(AttributeExtension):
def append(self, state, value, initiator):
print("%s::append > Checkpoint!. Value: %s, state.obj()::%s" %
(self.__class__.__name__, value, state.obj()))
return value
def remove(self, state, value, initiator):
print("%s::append > Checkpoint!. Value: %s, state.obj()::%s" %
(self.__class__.__name__, value, state.obj()))
return value
def set(self, state, value, oldValue, initiator):
print("%s::set > Checkpoint!. Value: %s, oldValue: %s,
state.obj().values: %s" % (self.__class__.__name__, value, oldValue,
state.obj().values))
return value
Let's say the initial (old) value was ["yes"] and I add a "no". I
would expect the "value" parameter in the set method to be ["yes",
"no"] and the oldValue to be ["yes"] but this is what I get:
ValuesAttributeExtension::set > Checkpoint!. Value: [], oldValue:
[u'yes'], state.obj().values: [u'yes']
The "append" or "remove" methods are never run... I guess that's
because it's a weird type (not really a relationship) so that's ok,
but I'd like to know if there's a way of getting the new value that is
going to be set, to check the differences.
Everything else seems to be working fine, though. Even though value is
an empty list in the "set" method, it gets properly updated in the
database.
Thank you in advance.
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