NAME

       Webapp::retrieveFunction - Retrieve saved state

SYNOPSIS

       b retrieveFunction( b() defn, String(String) retriever, String key )

ARGUMENTS

       defn The default function to call if the state key does not exist.

       retriever A function that returns the encoded state when given the key

       key The key to find the state

DESCRIPTION

       In  some  circumstances  you may need to store application state in an external source, so
       that a user may save their session and  return  to  it  later.   This  function  lets  you
       retrieve  a  saved state from an external source based on a key.  The function represented
       by the saved state is then executed. The retrieval function should throw an  Exception  if
       it  can't find the key, which will cause the default function defn to be executed instead.
       Otherwise, it should, given the key,  return  the  state  string  that  was  stored  using
       Webapp.storeFunction (3kaya)

       One  use  of  this is to generate links to be sent via email, where the links generated by
       Kaya containing the state data itself are too long to be practical.

       You should consider when writing the retrieval function whether the action  of  retrieving
       the state should delete it from the persistent storage.

AUTHORS

       Kaya  standard  library  by  Edwin Brady, Chris Morris and others (kaya@kayalang.org). For
       further information see http://kayalang.org/

LICENSE

       The Kaya standard library is free software; you can redistribute it and/or modify it under
       the  terms  of the GNU Lesser General Public License (version 2.1 or any later version) as
       published by the Free Software Foundation.

RELATED

       Webapp.runHandler (3kaya)
       Webapp.storeFunction (3kaya)