{dede:field name='source' runphp='yes'}
 if(@me == "") @me = "";else @me = "來源:".@me;
 {/dede:field}

{dede:field name='array' runphp='yes'}
if(@me['source'] == "") @me = "@me['其余變量']";
else @me = "來源:".@me['source'];
{/dede:field}