Added DjangoSessionCacheHandler (#691)

* Added DjangoSessionCacheHandler

Added `DjangoSessionCacheHandler`, a cache handler that stores the token in the session framework provided by Django. Web apps using spotipy with Django can directly use this for cache handling.

* removed whitespaces

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 
 * Added `MemoryCacheHandler`, a cache handler that simply stores the token info in memory as an instance attribute of this class.
+* Added `DjangoSessionCacheHandler`, a cache handler that stores the token in the session framework provided by Django. Web apps using spotipy with Django can directly use this for cache handling.
 
 ### Fixed
 

spotipy/cache_handler.py

@@ -1,4 +1,4 @@
-__all__ = ['CacheHandler', 'CacheFileHandler', 'MemoryCacheHandler']
+__all__ = ['CacheHandler', 'CacheFileHandler', 'DjangoSessionCacheHandler', 'MemoryCacheHandler']
 
 import errno
 import json
@@ -106,3 +106,35 @@ class MemoryCacheHandler(CacheHandler):
 
     def save_token_to_cache(self, token_info):
         self.token_info = token_info
+
+
+class DjangoSessionCacheHandler(CacheHandler):
+    """
+    A cache handler that stores the token info in the session framework
+    provided by Django.
+
+    Read more at https://docs.djangoproject.com/en/3.2/topics/http/sessions/
+    """
+
+    def __init__(self, request):
+        """
+        Parameters:
+            * request: HttpRequest object provided by Django for every
+            incoming request
+        """
+        self.request = request
+
+    def get_cached_token(self):
+        token_info = None
+        try:
+            token_info = self.request.session['token_info']
+        except KeyError:
+            logger.debug("Token not found in the session")
+
+        return token_info
+
+    def save_token_to_cache(self, token_info):
+        try:
+            self.request.session['token_info'] = token_info
+        except Exception as e:
+            logger.warning("Error saving token to cache: " + str(e))