Extracted json saving and loading (#10216)

homeassistant/components/media_player/plex.py

@@ -6,7 +6,6 @@ https://home-assistant.io/components/media_player.plex/
 """
 import json
 import logging
-import os
 from datetime import timedelta
 
 import requests
@@ -22,6 +21,7 @@ from homeassistant.const import (
     DEVICE_DEFAULT_NAME, STATE_IDLE, STATE_OFF, STATE_PAUSED, STATE_PLAYING)
 from homeassistant.helpers import config_validation as cv
 from homeassistant.helpers.event import track_utc_time_change
+from homeassistant.util.json import load_json, save_json
 
 REQUIREMENTS = ['plexapi==3.0.3']
 
@@ -48,35 +48,10 @@ PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend({
 })
 
 
-def config_from_file(filename, config=None):
-    """Small configuration file management function."""
-    if config:
-        # We're writing configuration
-        try:
-            with open(filename, 'w') as fdesc:
-                fdesc.write(json.dumps(config))
-        except IOError as error:
-            _LOGGER.error("Saving config file failed: %s", error)
-            return False
-        return True
-    else:
-        # We're reading config
-        if os.path.isfile(filename):
-            try:
-                with open(filename, 'r') as fdesc:
-                    return json.loads(fdesc.read())
-            except IOError as error:
-                _LOGGER.error("Reading config file failed: %s", error)
-                # This won't work yet
-                return False
-        else:
-            return {}
-
-
 def setup_platform(hass, config, add_devices_callback, discovery_info=None):
     """Set up the Plex platform."""
     # get config from plex.conf
-    file_config = config_from_file(hass.config.path(PLEX_CONFIG_FILE))
+    file_config = load_json(hass.config.path(PLEX_CONFIG_FILE))
 
     if file_config:
         # Setup a configured PlexServer
@@ -146,7 +121,7 @@ def setup_plexserver(
         _LOGGER.info("Discovery configuration done")
 
     # Save config
-    if not config_from_file(
+    if not save_json(
             hass.config.path(PLEX_CONFIG_FILE), {host: {
                 'token': token,
                 'ssl': has_ssl,

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