spotipy/spotipy/cache_handler.py

106 lines
2.9 KiB
Python

__all__ = ['CacheHandler', 'CacheFileHandler', 'MemoryCacheHandler']
import errno
import json
import logging
logger = logging.getLogger(__name__)
class CacheHandler():
"""
An abstraction layer for handling the caching and retrieval of
authorization tokens.
Custom extensions of this class must implement get_cached_token
and save_token_to_cache methods with the same input and output
structure as the CacheHandler class.
"""
def get_cached_token(self):
"""
Get and return a token_info dictionary object.
"""
# return token_info
raise NotImplementedError()
def save_token_to_cache(self, token_info):
"""
Save a token_info dictionary object to the cache and return None.
"""
raise NotImplementedError()
return None
class CacheFileHandler(CacheHandler):
"""
Handles reading and writing cached Spotify authorization tokens
as json files on disk.
"""
def __init__(self,
cache_path=None,
username=None):
"""
Parameters:
* cache_path: May be supplied, will otherwise be generated
(takes precedence over `username`)
* username: May be supplied or set as environment variable
(will set `cache_path` to `.cache-{username}`)
"""
if cache_path:
self.cache_path = cache_path
else:
cache_path = ".cache"
if username:
cache_path += "-" + str(username)
self.cache_path = cache_path
def get_cached_token(self):
token_info = None
try:
f = open(self.cache_path)
token_info_string = f.read()
f.close()
token_info = json.loads(token_info_string)
except IOError as error:
if error.errno == errno.ENOENT:
logger.debug("cache does not exist at: %s", self.cache_path)
else:
logger.warning("Couldn't read cache at: %s", self.cache_path)
return token_info
def save_token_to_cache(self, token_info):
try:
f = open(self.cache_path, "w")
f.write(json.dumps(token_info))
f.close()
except IOError:
logger.warning('Couldn\'t write token to cache at: %s',
self.cache_path)
class MemoryCacheHandler(CacheHandler):
"""
A cache handler that simply stores the token info in memory as an
instance attribute of this class. The token info will be lost when this
instance is freed.
"""
def __init__(self, token_info=None):
"""
Parameters:
* token_info: The token info to store in memory. Can be None.
"""
self.token_info = token_info
def get_cached_token(self):
return self.token_info
def save_token_to_cache(self, token_info):
self.token_info = token_info