Refactor XML parsing in rest (#94268)

* Refactor XML parsing in rest

* Adjust caplog check

* Adjust

* Rename

* Simplify

homeassistant/components/rest/const.py

@@ -26,3 +26,10 @@ REST = "rest"
 REST_DATA = "rest_data"
 
 METHODS = ["POST", "GET"]
+
+XML_MIME_TYPES = (
+    "application/rss+xml",
+    "application/xhtml+xml",
+    "application/xml",
+    "text/xml",
+)

homeassistant/components/rest/data.py

@@ -3,14 +3,19 @@ from __future__ import annotations
 
 import logging
 import ssl
+from xml.parsers.expat import ExpatError
 
 import httpx
+import xmltodict
 
 from homeassistant.core import HomeAssistant
 from homeassistant.helpers import template
 from homeassistant.helpers.httpx_client import create_async_httpx_client
+from homeassistant.helpers.json import json_dumps
 from homeassistant.util.ssl import SSLCipherList
 
+from .const import XML_MIME_TYPES
+
 DEFAULT_TIMEOUT = 10
 
 _LOGGER = logging.getLogger(__name__)
@@ -59,6 +64,26 @@ class RestData:
         """Set url."""
         self._resource = url
 
+    def data_without_xml(self) -> str | None:
+        """If the data is an XML string, convert it to a JSON string."""
+        _LOGGER.debug("Data fetched from resource: %s", self.data)
+        if (
+            (value := self.data) is not None
+            # If the http request failed, headers will be None
+            and (headers := self.headers) is not None
+            and (content_type := headers.get("content-type"))
+            and content_type.startswith(XML_MIME_TYPES)
+        ):
+            try:
+                value = json_dumps(xmltodict.parse(value))
+            except ExpatError:
+                _LOGGER.warning(
+                    "REST xml result could not be parsed and converted to JSON"
+                )
+            else:
+                _LOGGER.debug("JSON converted from XML: %s", self.data)
+        return value
+
     async def async_update(self, log_errors: bool = True) -> None:
         """Get the latest data from REST service with provided method."""
         if not self._async_client:

homeassistant/components/rest/sensor.py

@@ -3,11 +3,9 @@ from __future__ import annotations
 
 import logging
 import ssl
-from xml.parsers.expat import ExpatError
 
 from jsonpath import jsonpath
 import voluptuous as vol
-import xmltodict
 
 from homeassistant.components.sensor import (
     DOMAIN as SENSOR_DOMAIN,
@@ -26,7 +24,6 @@ from homeassistant.core import HomeAssistant
 from homeassistant.exceptions import PlatformNotReady
 import homeassistant.helpers.config_validation as cv
 from homeassistant.helpers.entity_platform import AddEntitiesCallback
-from homeassistant.helpers.json import json_dumps
 from homeassistant.helpers.template_entity import TemplateSensor
 from homeassistant.helpers.typing import ConfigType, DiscoveryInfoType
 from homeassistant.helpers.update_coordinator import DataUpdateCoordinator
@@ -127,26 +124,7 @@ class RestSensor(RestEntity, TemplateSensor):
 
     def _update_from_rest_data(self) -> None:
         """Update state from the rest data."""
-        value = self.rest.data
-        _LOGGER.debug("Data fetched from resource: %s", value)
-        if self.rest.headers is not None:
-            # If the http request failed, headers will be None
-            content_type = self.rest.headers.get("content-type")
-
-            if content_type and (
-                content_type.startswith("text/xml")
-                or content_type.startswith("application/xml")
-                or content_type.startswith("application/xhtml+xml")
-                or content_type.startswith("application/rss+xml")
-            ):
-                try:
-                    value = json_dumps(xmltodict.parse(value))
-                    _LOGGER.debug("JSON converted from XML: %s", value)
-                except ExpatError:
-                    _LOGGER.warning(
-                        "REST xml result could not be parsed and converted to JSON"
-                    )
-                    _LOGGER.debug("Erroneous XML: %s", value)
+        value = self.rest.data_without_xml()
 
         if self._json_attrs:
             self._attr_extra_state_attributes = {}

tests/components/rest/test_sensor.py

@@ -899,7 +899,7 @@ async def test_update_with_xml_convert_bad_xml(
     state = hass.states.get("sensor.foo")
 
     assert state.state == STATE_UNKNOWN
-    assert "Erroneous XML" in caplog.text
+    assert "REST xml result could not be parsed" in caplog.text
     assert "Empty reply" in caplog.text
 
 
@@ -936,7 +936,7 @@ async def test_update_with_failed_get(
     state = hass.states.get("sensor.foo")
 
     assert state.state == STATE_UNKNOWN
-    assert "Erroneous XML" in caplog.text
+    assert "REST xml result could not be parsed" in caplog.text
     assert "Empty reply" in caplog.text