Node js redis - undefined variable

Question

does not return when I call the function

function getSportId(lang, name, betcoid){
    redisClient.select(1, function(err,res){
        redisClient.get(lang+"_"+name, function (err, r) {
            let data = JSON.parse(r);
            return "xxx";
        });
    });
}

var print = getSportId(a,b,c);
console.log(print);

Console print return empty :/

Does this answer your question? [How do I return the response from an asynchronous call?](https://stackoverflow.com/questions/14220321/how-do-i-return-the-response-from-an-asynchronous-call) — Marcos Casagrande, May 12 '20 at 13:59
The function getSportId() doesn't have a return statement, so `print` will always be undefined. — tdurtsch, May 12 '20 at 15:03

score 0 · Answer 1 · edited Jun 20 '20 at 09:12

According to the documentation

Note that the API is entirely asynchronous. To get data back from the server, you'll need to use a callback.

Node Redis currently doesn't natively support promises (this is coming in v4), however you can wrap the methods you want to use with promises using the built-in Node.js util.promisify method on Node.js >= v8;

const redis = require("redis");
const redisClient = redis.createClient();
const util = require('util');
util.promisify(redisClient.get).bind(redisClient);

function getSportId (lang, name, betcoid) {
    return redisClient.select(1, function (err, res) {
        redisClient.get(lang + "_" + name, function (err, r) {
            console.log(r);
        });
    });
}

getSportId('my', 'foo')

Also be careful about selecting database 1. The default is 0. The following will work if you don't have to select 1.

function getSportId (lang, name, betcoid) {
    redisClient.get(lang + "_" + name, function (err, r) {
        console.log(r); //implement your callback
    });
}

Node js redis - undefined variable

1 Answers1