Hi all,
Is there way to use Column.onupdate conditionally? For example, say I have:
class A(Base):
foo = Column(String)
bar = Column(String)
foo_updated = Column(DateTime, onupdate=update_fn) # Should only update
when foo is updated
def update_fn(context):
if ...: # How can I check if only foo was updated?
return datetime.now()
else:
return ... # How can I say to not update?
Is there a way to define update_fn to only update foo_updated when foo
changes? I can look at context.get_current_parameters() to see what columns
are being used in the compiled statement, but it doesn't explicitly say
which columns are the ones actually being updated; for example, if I have
A.query.filter(A.bar == 'test').update({A.foo: 'new'},
synchronize_session=False)
then context.get_current_parameters will return a dict with keys for both
'bar' and 'foo', although it looks like it suffixes the filter param with a
'_1' - is that something I can rely on to know if a column is used as a
filter instead of an update? And beyond that, is there a way I can specify
to not update the column?
Alternatively, is there another approach recommended to doing this?
Thanks!
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