Scan strings using nodejs in redis

Question

I am trying to scan the string on redis server by using redis, redis-scanner module but it is not working..

Please find my code as below and written by node js. Any help would appreciated

var conf = require('./config.js'); //config file declarations
var restify = require('restify'); //restify included
var redis = require("redis"); //redis included
var redis_scanner = require('redis-scanner');

var client = redis.createClient(conf.get('redis_cm.redis_port'), conf.get('redis_cm.redis_server'));
    client.auth(conf.get('redis_cm.auth'), function (err) {
        if (err){
            throw err;
        }
    });
    client.on('connect', function() {
        console.log('Connected to Redis');
    });
    client.select(conf.get('redis_cm.database'), function() {
        console.log("Redis Database "+conf.get('redis_cm.database')+" selected successfully!..");
    });


var options = {
    args: ['MATCH','CM:*','COUNT','5'],
    onData: function(result, done){
        console.log(result);
        console.log("result");
        client.quit();    
        process.exit(1);
    },
    onEnd: function(err){
        console.log("error");
    }
};

var scanner = new redis_scanner.Scanner(client, 'SCAN', null, options);

Could you be more specific? What exactly are you trying to do, and where in your code does it break down? What works, what doesn't work? — Niels Abildgaard
– Niels Abildgaard, Commented May 23, 2016 at 19:18
I would want to scan the redis database and need to get the keys. for that I used redis and redis-scanner nodejs modules. Please find the above script.. I am connect the redis database but I unable to scan the keys.. Any help that would be appreciated. Thanks in advance!.. — Vimal Jesurathinam
– Vimal Jesurathinam, Commented May 23, 2016 at 19:23

raghav · Accepted Answer · 2016-08-28 13:22:30Z

7

You can use the scan command available in redis from version 2.8.0. Check the documentation from http://redis.io/commands/scan.

Sample code:

var cursor = '0';

function scan(){
  redisClient.scan(cursor, 'MATCH', 'CM:*', 'COUNT', '5', function(err, reply){
    if(err){
        throw err;
    }
    cursor = reply[0];
    if(cursor === '0'){
        return console.log('Scan Complete');
    }else{
        // do your processing
        // reply[1] is an array of matched keys.
        // console.log(reply[1]);
        return scan();
    }
  });
}

scan(); //call scan function

edited Aug 28, 2016 at 13:22

answered May 24, 2016 at 6:21

raghav

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2 Comments

ShaneTheKing Over a year ago

The && reply[1].length === 0 should be removed from the if statement, a scan terminates when the cursor returns 0, regardless if there were keys returned in the last scan or not. This will cause infinite loops...

ShaneTheKing Over a year ago

Forgot to mention, you should still process data even if it is the last result in the scan.

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