Flask-IIIF custom cache example

config.py

# In your overlay's configuration (/s/overlay/YOUR_OVERLAY)
IIIF_CACHE_HANDLER = 'overlay.utils:FileSystemCache'

utils.py

import os

from flask_iiif.cache import ImageCache

class FileSystemCache(ImageCache):
  
  """File system cache."""
  
    def __init__(self):
        """Initialize the cache."""
        super(ImageSimpleCache, self).__init__()

    def get(self, key):
        """Return the key value.
        :param string key: the object's key
        :return: the stored object
        :rtype: `BytesIO` object
        """
        # Make sure to return a BytesIO object
        with open(key) as image:
          return image.read()
        

    def set(self, key, value, timeout=0):
        """Cache the object.
        :param string key: the object's key
        :param value: the stored object
        :type value: `BytesIO` object
        :param int timeout: the cache timeout in seconds
        """
        with open(key, "w") as image:
          image.write(value)

    def delete(self, key):
        """Delete the specific key."""
        os.remove(key)

    def flush(self):
        """Flush the cache."""
        # Delete the whole cache folder
        raise NotImplementedError()