Support adding and removing entities to devices

[postlund]

This is not what I should be working on, but I had most of the code sitting on a branch so I decided to finish it.

New entities can be added via + button under Integrations (like when adding a new device, but select an existing device instead) and entities can be removed from Options.

[ultratoto14]

Hi @postlund, just tested it, here are my remarks:

• When adding a new entity to an existing one, the already used DP ids are proposed.
• At the end the label is not what is expected, "Abandonné" means "canceled"
  
• At the same time i have an exception in the logs, but the entity was well created:

2020-11-26 10:53:01 ERROR (MainThread) [homeassistant.config_entries] Error unloading entry Tempo for sensor
Traceback (most recent call last):
  File "/usr/src/homeassistant/homeassistant/config_entries.py", line 321, in async_unload
    result = await component.async_unload_entry(hass, self)  # type: ignore
  File "/usr/src/homeassistant/homeassistant/components/sensor/__init__.py", line 72, in async_unload_entry
    return await hass.data[DOMAIN].async_unload_entry(entry)
  File "/usr/src/homeassistant/homeassistant/helpers/entity_component.py", line 172, in async_unload_entry
    raise ValueError("Config entry was never loaded!")
ValueError: Config entry was never loaded!

• When trying to add a new entity, yaml defined entries are proposed, if i choose one i have an error, nothing in the logs
  

[postlund]

Thanks for testing @ultratoto14! Let's see if I can answer...

Hmm, that's strange. Is it always like that or only when you add a new entity to a device that you added during the same "session"? Because I know that the browser sometimes cache values and fill those in for some reason. I at least don't have any code for auto-filling values (that's part of #125, which isn't merged yet).

That's a limitation of the entry flow framework. There's only two ways out: creating a new config entry or aborting (yielding the "canceled" message). Since we already have a config entry, that leaves out the first one (which also would request the user to assign the device to a room again), leaving only the abort method. Fact is that this is the de-facto way of doing things like this, e.g. when reconfiguring credentials for a device. So you will see it in the built in components as well.

The exception I don't know the reason for, will have to look into that.

Right, good catch. I will make sure to filter out devices set up via YAML.

[ultratoto14]

Hmm, that's strange. Is it always like that or only when you add a new entity to a device that you added during the same "session"? Because I know that the browser sometimes cache values and fill those in for some reason. I at least don't have any code for auto-filling values (that's part of #125, which isn't merged yet).

Hi @postlund, I remember that the filtered already used DP is only for the ID, it was on a PR already merged. So it's normal then, I set up a light with multiple DP used and expect that these will not be present in the dropdown list, but this applies only to ID, my bad.

[ultratoto14]

@postlund should I retest this one ?

[postlund]

@ultratoto14 Yes please, forgot to ping you about it.

[ultratoto14]

Code looks good 👍
Tests are Ok:

• Adding new device 👍
• Adding entity to device 👍
• Removing entity from device 👍
• YAML devices not listed 👍
• Already configured and not yet configured are there in list 👍

[postlund]

Great! 👍 Let's merge before I charge my mind.

[postlund]

🎉