Jam.py documentation

on_open_events

When the open method of the item is called on the client or the server, the server application executes the following code:

result = None
if self.task.on_open:
    result = self.task.on_open(self, params)
if result is None and self.on_open:
    result = self.on_open(self, params)
if result is None:
    result = self.execute_open(params)

It checks if the task has an on_open event handler. If the on_open event handler is declared in the task server module, it is executed.

If the on_open event handler of the task is not declared or the result of the event handler returns None, the method checks whether the item has an on_open event handler. If it is declared in the item server module, it is executed.

If the result returned by the item event handler is None, the execute_open method of the item is called that generates SQL query, execute it and returns the result