def save_fetched_table_if_changed(wfm: WfModule, new_table: DataFrame,
error_message: str) -> datetime.datetime:
"""Store retrieved data table, if it is a change from wfm's existing data.
"Change" here means either a changed table or changed error message.
The WfModule's `status` and `error_msg` will be set, according to
`error_message`.
Set wfm.last_update_check, regardless.
Create (and run) a ChangeDataVersionCommand.
Notify the user.
Return the timestamp (if changed) or None (if not).
"""
with wfm.workflow.cooperative_lock():
wfm.last_update_check = timezone.now()
# Store this data only if it's different from most recent data
version_added = wfm.store_fetched_table_if_different(new_table)
if version_added:
enforce_storage_limits(wfm)
wfm.error_msg = error_message or ''
wfm.status = (WfModule.ERROR if error_message else WfModule.READY)
wfm.save()
# un-indent: COMMIT, so we can notify the client and the client sees changes
if version_added:
ChangeDataVersionCommand.create(wfm,
version_added) # also notifies client
if wfm.notifications == True:
Notification.create(wfm, "New data version available")
else:
# no new data version, but we still want client to update WfModule status and last update check time
notify_client_workflow_version_changed(wfm.workflow)
return version_added
