title: unique random key redis lua script
body: <p>Absolutely new to lua.. just started 1 hr ago :) . I want to generate randomid and make sure that key with same id doesn't exists in redis. So i have written below code in lua</p>
  
  <pre><code>local get_random_id
  get_random_id = function(id)
      local id_exists = redis.call("EXISTS", id)
      if id_exists == 0 then
           return id 
      end
      local newid = randomstring(3)
      get_random_id(newid)
  end
  
  local id = randomstring(3)
  local existingid = "abc"
  return get_event_id(existingid) 
  </code></pre>
  
  <p>It works fine if i pass the key which doesn't exists in the redis it returns me a new random key. However if key exists in redis it returns me nil. </p>
  
  <p>More Info: I MONITOR redis and found script is generating the random string and checking in redis but somehow it returning nil</p>