lp.services.webapp.snapshot : API documentation

@contextmanager
def notify_modified(obj, edited_fields, snapshot_names=None, user=None):

A context manager that notifies about modifications to an object.

Use this as follows:

with notify_modified(obj, ["attr"]):
    obj.attr = value

Or:

edited_fields = set()
with notify_modified(obj, edited_fields):
    if obj.attr != new_attr:
        obj.attr = new_attr
        edited_fields.add("attr")

Or even:

edited_fields = set()
with notify_modified(obj, edited_fields) as previous_obj:
    do_something()
    if obj.attr != previous_obj.attr:
        edited_fields.add("attr")

Parameters	obj	The object being modified.
	edited_fields	An iterable of fields being modified. This is not used until after the block wrapped by the context manager has finished executing, so you can safely pass a mutable object and add items to it from inside the block as you determine which fields are being modified. A notification will only be sent if `edited_fields` is non-empty.
	snapshot_names	If not None, only snapshot these names. This may be used if snapshotting some of the object's attributes is expensive in some contexts (and they can't be wrapped by `doNotSnapshot` for some reason).
	user	If not None, the user making these changes. If None, defaults to the principal registered in the current interaction.

Function	snapshot_sql_result	Snapshot adapter for the Storm result set.
Function	notify_modified	A context manager that notifies about modifications to an object.

l.s.w.snapshot : module documentation