Extracted json saving and loading (#10216)

homeassistant/util/json.py

@@ -0,0 +1,50 @@
+"""JSON utility functions."""
+import logging
+from typing import Union, List, Dict
+
+import json
+
+from homeassistant.exceptions import HomeAssistantError
+
+_LOGGER = logging.getLogger(__name__)
+
+
+def load_json(filename: str) -> Union[List, Dict]:
+    """Load JSON data from a file and return as dict or list.
+
+    Defaults to returning empty dict if file is not found.
+    """
+    try:
+        with open(filename, encoding='utf-8') as fdesc:
+            return json.loads(fdesc.read())
+    except FileNotFoundError:
+        # This is not a fatal error
+        _LOGGER.debug('JSON file not found: %s', filename)
+    except ValueError as error:
+        _LOGGER.exception('Could not parse JSON content: %s', filename)
+        raise HomeAssistantError(error)
+    except OSError as error:
+        _LOGGER.exception('JSON file reading failed: %s', filename)
+        raise HomeAssistantError(error)
+    return {}  # (also evaluates to False)
+
+
+def save_json(filename: str, config: Union[List, Dict]):
+    """Save JSON data to a file.
+
+    Returns True on success.
+    """
+    try:
+        data = json.dumps(config, sort_keys=True, indent=4)
+        with open(filename, 'w', encoding='utf-8') as fdesc:
+            fdesc.write(data)
+            return True
+    except TypeError as error:
+        _LOGGER.exception('Failed to serialize to JSON: %s',
+                          filename)
+        raise HomeAssistantError(error)
+    except OSError as error:
+        _LOGGER.exception('Saving JSON file failed: %s',
+                          filename)
+        raise HomeAssistantError(error)
+    return False