Signals not always emitted on model changes

[mrvisscher]

For some reason the on_database_metadata_change is not sent when you delete a database from the databases metadata. signal=False is hardcode instead of it using the signal parameter that defaults to True. I think the expected behavior would be for the signal to fire on database deletion as well.

brightway2-data/bw2data/meta.py

Lines 105 to 125 in 4fd8e93

	def __delitem__(self, name: str, signal: bool = True):
	from bw2data import Database
	if name not in self:
	raise KeyError
	try:
	Database(name).delete(warn=False, signal=False)
	except:
	warnings.warn(
	"""
	Deletion unsuccessful due to database error.
	Metadata state is unchanged, but database state is unknown.
	"""
	)
	return
	super(Databases, self).__delitem__(name=name, signal=False)
	if signal:
	on_database_delete.send(name=name)

[mrvisscher]

Same goes for parameterized exchanges:

brightway2-data/bw2data/parameters.py

Line 855 in 4fd8e93

ActivityParameter.recalculate_exchanges(group, signal=False)

Exchanges are recalculated, but the signal is hardcoded to False. The signal is not emitted meaning models dependent on that signal will be out of sync.

[mrvisscher]

Similarly, it would be very useful to get a signal for exchanges being modified when parameters are updated, but signals default back to false:

brightway2-data/bw2data/parameters.py

Lines 870 to 873 in 4fd8e93

	for obj in ParameterizedExchange.select().where(ParameterizedExchange.group == group):
	exc = ExchangeDataset.get(id=obj.exchange)
	exc.data["amount"] = interpreter(obj.formula)
	exc.save(signal=False)

[mrvisscher]

Similarly, on database write, the default is not True but defined by projects.dataset.is_sourced

brightway2-data/bw2data/backends/base.py

Lines 606 to 609 in f9f3663

	if signal is None:
	signal = projects.dataset.is_sourced
	def merger(d1: dict, d2: dict) -> dict:

No problem when calling .write directly as we can set signal to true ourselves. But when calling .copy, .write is called without defining signal=True, which means we don't get database write signals for copied databases.

brightway2-data/bw2data/backends/base.py

Line 236 in f9f3663

new_database.write(data, searchable=databases[name].get("searchable"))

On a related note: what is the sourced dataset functionality exactly? I can find many references to it in your code, but can find no documentation on it. I assume it has something to do with multi-user support?