CODEWITHSUNDEEP
node.jsredis
Dave de Sade
Dave de Sade

Reputation: 25

NodeJS nested Redis commands

I'm quite new to this stuff, but after few attempts, I would like to ask you for a help here, because I'm not sure, what exactly I'm doing wrong.

Situation: In Redis database, I got a key test with values like 1,2,3,4. To put new value into key, I use rpush, because I want to add new value at the end of the key (and when I run this standalone, it works as a charm):

client.rpush("test", "5");

However, my idea is, that first I would like to check out, if the key exists and if not, then I will add a value into it. For that I decided to use LRANGE command, now result looks like this:

client.lrange("test", 0, 0, function(err, reply) {
        if (reply.length === 0) {
            client.rpush("test", 5);
        }

Problem is, that in case described above, rpush seems to be 'ignored', it will not store the value. What am I doing wrong? It looks like any Redis command inside lrange callback is ignored.

Upvotes: 0

Views: 1298

Answers (1)

davissp14
davissp14

Reputation: 765

It sounds like you may be wanting to use LLEN instead of LRANGE.

https://redis.io/commands/llen

I am not a node guy, but something like this should work. Your example should work though, if this doesn't clear it up I would go ahead and update your description to include some logging. 

client.llen('test', function(err, reply) {  
  if (err) {
     // Log error
  }
  // Log reply 
  if (reply === 0) { 
    client.rpush('test', 5, function(err, reply) {
      if (err) {
         // Log error
      } 
      // Log reply
    })
  } 
})

Upvotes: 2

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