Why I keep getting this error " Wrong number of args calling Redis command From Lua script" even I get desired output

Question

I trying to execute this lua script i get proper output too. But i keep getting Wrong number of args calling Redis command From Lua script

def new_get_following(self, start, count, user_id=0):
        script = """
        local envs = redis.call('zrevrange',KEYS[1],ARGV[3],ARGV[4]);
        redis.call('sadd',ARGV[1],unpack(envs));
        local favs = redis.call('sinter',ARGV[2],ARGV[1]);
        local acts= redis.call('mget',unpack(envs));
        redis.call('del',ARGV[1]);
        return {favs,envs,acts}
        """
        count = int(start) + int(count) - 1
        print count
        fav_key = self.fav_key + ":" + str(user_id)
        following_stream_key = self.following_stream_key + ":" + str(user_id)
        tmp_key = int(time.time())
        return self.exectute(script, args=[tmp_key, fav_key, start, count], keys=[following_stream_key])

Asked By: jayprakashstar

||

Source

Answer 1

Maybe it is just a typo and has already been corrected but:

self.exectute shouldn’t it be self.execute?

Answered By: Ignacio

Answer 2

In the code last line is causing error.

local envs = redis.call('zrevrange',KEYS[1],ARGV[3],ARGV[4]);
local acts= redis.call('mget',unpack(envs));

As if envs is empty table then second line:

local acts= redis.call('mget',unpack(envs));

becomes this:

local acts= redis.call('mget',unpack());

so lua keeps throwing error. For avoid this error we can use redis.pacall which gives Response error object which can be checked in output can handle error. So final code should be

def new_get_following(self, start, count, user_id=0):
        script = """
        local envs = redis.call('zrevrange',KEYS[1],ARGV[3],ARGV[4]);
        redis.call('sadd',ARGV[1],unpack(envs));
        local favs = redis.call('sinter',ARGV[2],ARGV[1]);
        local acts= redis.pcall('mget',unpack(envs));
        redis.call('del',ARGV[1]);
        return {favs,envs,acts}
        """
        count = int(start) + int(count) - 1
        print count
        fav_key = self.fav_key + ":" + str(user_id)
        following_stream_key = self.following_stream_key + ":" + str(user_id)
        tmp_key = int(time.time())
        return self.exectute(script, args=[tmp_key, fav_key, start, count], keys=[following_stream_key])

Answered By: jayprakashstar

Why I keep getting this error " Wrong number of args calling Redis command From Lua script" even I get desired output

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