control_cache_decorator.py

"""
This Python Flask view decorator can be used to control browser cache settings
which is useful for REST APIs where IE and a few others tend to cache
the response rather than update the data.
"""

# Example usage:
@app.route('/my_api')
@control_cache(hours=0, content_type='application/json')
def my_api():
  return json.dumps({'Hello World': 'Hello Back'}

def control_cache(hours=10, content_type='text/html; charset=utf-8'):
    """ Flask decorator that allow to set Expire and Cache headers. """
    def fwrap(f):
        @wraps(f)
        def wrapped_f(*args, **kwargs):
            r = f(*args, **kwargs)
            then = datetime.now() + timedelta(hours=hours)
            rsp = Response(r, content_type=content_type)
            rsp.headers.add('Expires', then.strftime("%a, %d %b %Y %H:%M:%S GMT"))
            rsp.headers.add('Cache-Control', 'public,max-age=%d' % int(3600 * hours))
            return rsp
        return wrapped_f
    return fwrap