Register flask.current_app.teardown_appcontext only once

[jsarchibald]

SQL update: only register the shutdown_session function once to the Flask teardown_appcontext_funcs. Checks existing teardown functions before registering it.

[kzidane]

I wonder if it would make more sense for the flag to be set on the execute function itself such that it could do something like:

def execute(...):
  ...
 
  # Ensure shutdown_session is just added once
  if not execute.teardown_appcontext_added:
    execute.teardown_appcontext_added = True

    # Register shutdown_session on app context teardown    
    @flask_current_app.teardown_appcontext
    def shutdown(...):
      ...

# teardown_appcontext handler is not registered initially
execute.teardown_appcontext_added = False

instead of having to search through the list of teardown_appcontext_funcs repeatedly? Also, fwiw, I don't think function names uniquely identifies a function in this case (i.e., more than one teardown_appcontext handler could have the same name).

[jsarchibald]

Created an instance variable, teardown_appcontext_added, to the SQL class to do this.