unique random key redis lua script

Question

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

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)

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.

More Info: I MONITOR redis and found script is generating the random string and checking in redis but somehow it returning nil

Community · Accepted Answer · 2014-07-04 12:27:19Z

4

You are not returning the new random id from your recursive call.

Replace the line:

get_random_id(newid)

with:

return get_random_id(newid)

BTW, you can replace the definition of your function with just:

local function get_random_id(id)
    -- ... code ..
end

instead of

local get_random_id
get_random_id = function(id)
    -- ... code ..
end

edited Jul 4, 2014 at 12:27

CommunityBot

11 silver badge

answered Sep 11, 2013 at 4:55

LorenzoDonati4Ukraine-OnStrike

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9 Comments

Jack Daniel's Over a year ago

Thanks for reply but if i put the return there what if this number is also exists in the redis? I think i am messing up in code somewhere.. What i want it to generate a random number and check for existence in redis until i get a number which doesnt exists

Jack Daniel's Over a year ago

and by the way if i change function to local function get_random_id(id) it generates error "Script attempted to access unexisting global variable" as redis interpreter cant access global variables

Jack Daniel's Over a year ago

Discard my first comment.. May be i am sleeping.. thanks for the response.. it works :)

LorenzoDonati4Ukraine-OnStrike Over a year ago

@Atul If it solved your problem you may consider accepting my answer.

Jack Daniel's Over a year ago

by the way if u can help me out with the padding also so if number is 1 i want to pad it to 0 and make it 0001

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