old_contents: from flask_login import UserMixin
  import spotify
  import spotipy
  import db_utils
  import application as app
  
  
  class User(UserMixin):
      ''' User class for Flask-Login '''
      def __init__(self, user_id, username=None):
          self.id = int(user_id)
          self.username = username
          self._spotify = None
  
      @property
      def spotify(self):
          oa_client = spotify.sp_oauth
          # Fetch credentials from database
          if not self._spotify:
              self._spotify = db_utils.spotify_creds_for_user(app.engine,
                                                              self.id)
          # No credentials exist for user
          if self._spotify is None:
              return None
          # Refresh tokens if nescessary
          if oa_client.is_token_expired(self._spotify):
              self._spotify = oa_client.refresh_access_token(self._spotify)
  
          # Save/return new credentials if possible
          if self._spotify:
              db_utils.spotify_credentials_upsert(app.engine,
                                                  self.id,
                                                  self._spotify)
              return spotipy.Spotify(auth=self._spotify['access_token'])
  
  
  class Playlist(object):
      ''' Playlist object representation '''
      def __init__(self, playlist_id, title=None, duration=0, count=0):
          self.id = playlist_id
          self.title = title
          self.duration = duration
          self.count = count
  
new_contents: from flask_login import UserMixin
  import spotify
  import spotipy
  import db_utils
  import application as app
  
  
  class User(UserMixin):
      ''' User class for Flask-Login '''
      def __init__(self, user_id, username=None):
          self.id = int(user_id)
          self.username = username
          self._spotify = None
  
      @property
      def spotify(self):
          oa_client = spotify.sp_oauth
          # Fetch credentials from database
          if not self._spotify:
              self._spotify = db_utils.spotify_creds_for_user(app.engine,
                                                              self.id)
          # No credentials exist for user
          if self._spotify is None:
              return None
          # Refresh tokens if nescessary
          if oa_client.is_token_expired(self._spotify):
              print("Spotify token expired for {}.".format(self.username))
              self._spotify = oa_client.refresh_access_token(
                  self._spotify.get('refresh_token'))
  
          # Save/return new credentials if possible
          if self._spotify:
              db_utils.spotify_credentials_upsert(app.engine,
                                                  self.id,
                                                  self._spotify)
              return spotipy.Spotify(auth=self._spotify['access_token'])
  
  
  class Playlist(object):
      ''' Playlist object representation '''
      def __init__(self, playlist_id, title=None, duration=0, count=0):
          self.id = playlist_id
          self.title = title
          self.duration = duration
          self.count = count
  
subject: Fix token refresh for spotify credentials