from django.utils.hashcompat import md5_constructor

drop_chars = ''.join(['%c' % c for c in range(32)]) + ' '

def cache_key_clean(value):
    """
    Make a key of the first up to 228 valid characters of the value,
    appended with the md5 of the whole value.
    """
    md5_hash = md5_constructor(value).hexdigest()
    return ''.join([value.translate(None,drop_chars)[:228], md5_hash])