Make redis dependency optional

CHANGELOG.md

@@ -12,6 +12,10 @@ While this is unreleased, please only add v3 features here. Rebasing master onto
 ### Added
 
 * `Scope` - An enum which contains all of the authorization scopes (see [here](https://github.com/plamere/spotipy/issues/652#issuecomment-797461311)).
+* Added `RedisCacheHandler`, a cache handler that stores the token info in Redis.
+* Added a new parameter to `RedisCacheHandler` to allow custom keys (instead of the default `token_info` key)
+* Simplify check for existing token in `RedisCacheHandler`
+* Make redis an optional dependency
 
 ### Changed
 
@@ -475,4 +479,4 @@ Repackaged for saner imports
 
 ## [1.0.0] - 2017-04-05
 
-Initial release
+Initial release

README.md

@@ -20,6 +20,12 @@ or upgrade
 pip install spotipy --upgrade
 ```
 
+Spotipy includes optional support for caching Spotify access tokens to a Redis server. To use this support, make sure to specify the `redis` extra:
+
+```bash
+pip install spotipy[redis]
+```
+
 ## Quick Start
 
 A full set of examples can be found in the [online documentation](http://spotipy.readthedocs.org/) and in the [Spotipy examples directory](https://github.com/plamere/spotipy/tree/master/examples).

docs/index.rst

@@ -226,6 +226,10 @@ The custom cache handler would need to be a class that inherits from the base
 cache handler ``CacheHandler``. The default cache handler ``CacheFileHandler`` is a good example.
 An instance of that new class can then be passed as a parameter when
 creating ``SpotifyOAuth``, ``SpotifyPKCE`` or ``SpotifyImplicitGrant``.
+The following handlers are available and defined in the URL above.
+  - ``CacheFileHandler``
+  - ``MemoryCacheHandler``
+  - ``RedisCacheHandler``
 
 Feel free to contribute new cache handlers to the repo.
 

setup.py

@@ -11,9 +11,15 @@
     'Sphinx>=1.5.2'
 ]
 
+redis_reqs = [
+    "redis>=3.5.3",
+    "redis<4.0.0;python_version<'3.4'",
+]
+
 extra_reqs = {
     'doc': doc_reqs,
-    'test': test_reqs
+    'test': test_reqs,
+    'redis': redis_reqs,
 }
 
 setup(

spotipy/cache_handler.py

@@ -1,13 +1,19 @@
 # -*- coding: utf-8 -*-
 
-__all__ = ['CacheHandler', 'CacheFileHandler', 'MemoryCacheHandler']
+__all__ = [
+    'CacheHandler',
+    'CacheFileHandler',
+    'MemoryCacheHandler',
+    'RedisCacheHandler'
+]
 
 import errno
 import json
 import logging
 import os
 from spotipy.util import CLIENT_CREDS_ENV_VARS
 from abc import ABC, abstractmethod
+import warnings
 
 logger = logging.getLogger(__name__)
 
@@ -107,3 +113,49 @@ def get_cached_token(self):
 
     def save_token_to_cache(self, token_info):
         self.token_info = token_info
+
+
+class RedisCacheHandler(CacheHandler):
+    """
+    A cache handler that stores the token info in the Redis.
+    """
+
+    def __init__(self, redis, key=None):
+        """
+        Parameters:
+            * redis: Redis object provided by redis-py library
+            (https://github.com/redis/redis-py)
+            * key: May be supplied, will otherwise be generated
+                   (takes precedence over `token_info`)
+        """
+        self.redis = redis
+        self.key = key if key else 'token_info'
+
+        try:
+            from redis import RedisError
+        except ImportError:
+            warnings.warn(
+                'Error importing module "redis"; '
+                'it is required for RedisCacheHandler',
+                UserWarning
+            )
+
+    def get_cached_token(self):
+        token_info = None
+        from redis import RedisError
+
+        try:
+            token_info = self.redis.get(self.key)
+            if token_info:
+                return json.loads(token_info)
+        except RedisError as e:
+            logger.warning('Error getting token from cache: ' + str(e))
+
+        return token_info
+
+    def save_token_to_cache(self, token_info):
+        from redis import RedisError
+        try:
+            self.redis.set(self.key, json.dumps(token_info))
+        except RedisError as e:
+            logger.warning('Error saving token to cache: ' + str(e))