zha: Clean up listener registration and button state

[rcloran]

• Instead of registering listeners in the entity init, do it in
  async_added_to_hass to avoid errors updating an entity which isn't fully
  set up yet
• schedule_update_ha_state -> async_schedule_update_ha_state

Description:

Related issue (if applicable): fixes #

Pull request in home-assistant.github.io with documentation (if applicable): home-assistant/home-assistant.github.io#<home-assistant.github.io PR number goes here>

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[houndci-bot]

line too long (81 > 79 characters)

[balloob]

For a future PR: add async_will_remove_from_hass and you're almost able to load/unload ZHA while Home Assistant is running 👍

[balloob]

This is called from an async context?

[rcloran]

@MartinHjelmare's comments on #12528 suggested I should change this ... but, reading the code, it looks like I shouldn't be changing this. These are run from callbacks. Since async_... is a coro, I'd need to ensure it runs, and that's exactly what the schedule_... does.

[MartinHjelmare]

We need to know what is calling the callback, a thread or the event loop. That was my question.

[rcloran]

The event loop

[balloob]

Ok, in that case async_schedule_update_ha_state() is ok

[rcloran]

Since that is a coro, doesn’t it need to be scheduled anyways?

[rcloran]

Doh, I was reading async_update_ha_state, not async_schedule_update_ha_state. Alright, this all makes much more sense now.

[MartinHjelmare]

This will reset the listeners added in the child. You can init the parent before the setting the rest of the child's attributes.

[MartinHjelmare]

Great!