Improve restoring UniFi POE entity state (#47148)

* Improve restoring data and better handling when the restore data is empty
Improve readability of some logic related to POE clients

* There is no need to check clients_all in Switch platform

* Add better tests when restoring state

* Port except handling shouldn't be needed anymore

* Walrusify get_last_state

homeassistant/components/unifi/controller.py

@@ -40,6 +40,7 @@ from homeassistant.core import callback
 from homeassistant.exceptions import ConfigEntryNotReady
 from homeassistant.helpers import aiohttp_client
 from homeassistant.helpers.dispatcher import async_dispatcher_send
+from homeassistant.helpers.entity_registry import async_entries_for_config_entry
 from homeassistant.helpers.event import async_track_time_interval
 import homeassistant.util.dt as dt_util
 
@@ -338,21 +339,18 @@ class UniFiController:
 
         self._site_role = description[0]["site_role"]
 
-        # Restore clients that is not a part of active clients list.
+        # Restore clients that are not a part of active clients list.
         entity_registry = await self.hass.helpers.entity_registry.async_get_registry()
-        for entity in entity_registry.entities.values():
-            if (
-                entity.config_entry_id != self.config_entry.entry_id
-                or "-" not in entity.unique_id
-            ):
+        for entry in async_entries_for_config_entry(
+            entity_registry, self.config_entry.entry_id
+        ):
+            if entry.domain == TRACKER_DOMAIN:
+                mac = entry.unique_id.split("-", 1)[0]
+            elif entry.domain == SWITCH_DOMAIN:
+                mac = entry.unique_id.split("-", 1)[1]
+            else:
                 continue
 
-            mac = ""
-            if entity.domain == TRACKER_DOMAIN:
-                mac = entity.unique_id.split("-", 1)[0]
-            elif entity.domain == SWITCH_DOMAIN:
-                mac = entity.unique_id.split("-", 1)[1]
-
             if mac in self.api.clients or mac not in self.api.clients_all:
                 continue
 
@@ -360,7 +358,7 @@ class UniFiController:
             self.api.clients.process_raw([client.raw])
             LOGGER.debug(
                 "Restore disconnected client %s (%s)",
-                entity.entity_id,
+                entry.entity_id,
                 client.mac,
             )