How to add menu actions to a Qt session¶

A Qt session can offer commands in its menus and toolbars without a view for each, such as "turn on verbose logging" or "open the data folder". You list them in the actions section of the session file.

Declare an action¶

Each entry takes the fields of an app-model Action:

actions:
  - id: myapp.log.verbose
    title: Verbose logging
    callback: "mylab.contributions:enable_debug_logging"
    menus: [{ id: "myapp/settings" }]

• id names the command, and must be unique in the session.
• title is what the menu shows.
• callback is the function to run, written module:function.
• menus lists the menus the command appears in, by menu id.

The session reads the section while it builds, and registers every action on the app-model Application it owns. Reading the section imports nothing: the callback is imported the first time someone runs the command.

Write the callback¶

A callback is an ordinary function. The session fills its parameters by type from the same values the components were built from, so it can ask for the session's Settings, a shared value, or the devices:

# mylab/contributions.py
import logging

from redsun.log import set_level


def enable_debug_logging() -> None:
    set_level(logging.DEBUG)

Show the menu¶

An action appears in a menu only when the window shows that menu, so show the menu from a configure_main_view hook, which receives the main window:

from app_model.backends.qt import QModelMainWindow

from redsun.qt import SAVE_MENU


class Menus:
    def configure_main_view(self, view: QModelMainWindow) -> None:
        view.setModelMenuBar({SAVE_MENU: "File", "myapp/settings": "Settings"})

The keys are menu ids, and the values are the titles shown.

SAVE_MENU is the menu redsun puts its own commands in, such as Save configuration as.... Include it to offer them.

Read a failure¶

A wrong entry raises ActionError from redsun.qt while the session builds, naming the entry: