def _get_dav_getctag(self, cr):
     dirobj = self.context._dirobj
     uid = self.context.uid
     ctx = self.context.context.copy()
     ctx.update(self.dctx)
     where = [('collection_id','=',self.dir_id)]
     bc_obj = dirobj.pool.get('basic.calendar')
     
     res = get_last_modified(bc_obj, cr, uid, where, context=ctx)
     return _str2time(res)
 def _get_dav_getctag(self, cr):
     dirobj = self.context._dirobj
     uid = self.context.uid
     ctx = self.context.context.copy()
     ctx.update(self.dctx)
     where = [('collection_id','=',self.dir_id)]
     bc_obj = dirobj.pool.get('basic.calendar')
     
     res = get_last_modified(bc_obj, cr, uid, where, context=ctx)
     return _str2time(res)