Allow get_states to recover (#67146)

homeassistant/components/websocket_api/commands.py

@@ -34,6 +34,10 @@ from homeassistant.helpers.json import ExtendedJSONEncoder
 from homeassistant.helpers.service import async_get_all_descriptions
 from homeassistant.loader import IntegrationNotFound, async_get_integration
 from homeassistant.setup import DATA_SETUP_TIME, async_get_loaded_integrations
+from homeassistant.util.json import (
+    find_paths_unserializable_data,
+    format_unserializable_data,
+)
 
 from . import const, decorators, messages
 from .connection import ActiveConnection
@@ -225,7 +229,35 @@ def handle_get_states(
             if entity_perm(state.entity_id, "read")
         ]
 
-    connection.send_result(msg["id"], states)
+    # JSON serialize here so we can recover if it blows up due to the
+    # state machine containing unserializable data. This command is required
+    # to succeed for the UI to show.
+    response = messages.result_message(msg["id"], states)
+    try:
+        connection.send_message(const.JSON_DUMP(response))
+        return
+    except (ValueError, TypeError):
+        connection.logger.error(
+            "Unable to serialize to JSON. Bad data found at %s",
+            format_unserializable_data(
+                find_paths_unserializable_data(response, dump=const.JSON_DUMP)
+            ),
+        )
+    del response
+
+    # If we can't serialize, we'll filter out unserializable states
+    serialized = []
+    for state in states:
+        try:
+            serialized.append(const.JSON_DUMP(state))
+        except (ValueError, TypeError):
+            # Error is already logged above
+            pass
+
+    # We now have partially serialized states. Craft some JSON.
+    response2 = const.JSON_DUMP(messages.result_message(msg["id"], ["TO_REPLACE"]))
+    response2 = response2.replace('"TO_REPLACE"', ", ".join(serialized))
+    connection.send_message(response2)
 
 
 @decorators.websocket_command({vol.Required("type"): "get_services"})