CODEWITHSUNDEEP
javascriptnode.jsrediskey-value
Bhushan Gadekar
Bhushan Gadekar

Reputation: 13805

how to get all keys and values in redis in javascript?

I am creating a node API using javascript. I have used redis as my key value store. I created a redis-client in my app and am able to get values for perticular key.

I want to retrieve all keys along with their values. So Far I have done this :

app.get('/jobs', function (req, res) {
    var jobs = [];
    client.keys('*', function (err, keys) {
        if (err) return console.log(err);
        if(keys){
            for(var i=0;i<keys.length;i++){
                client.get(keys[i], function (error, value) {
                    if (err) return console.log(err);
                    var job = {};
                    job['jobId']=keys[i];
                    job['data']=value;
                    jobs.push(job);
                });  
            }
            console.log(jobs);
            res.json({data:jobs});
        }
    });
});

but I always get blank array in response.

is there any way to do this in javascript?

Thanks

Upvotes: 25

Views: 69480

Answers (4)

Adam Eri
Adam Eri

Reputation: 965

You should never do this. First off, it is not recommended to use KEYS * in production. Second, this does not scale (cluster).

You can organise your cached entries into SETs and query for the items within the SET, then retrieve the references keys. This also makes invalidation easier.

Have a look at some data storage best practices.

https://redis.io/topics/data-types-intro how to get all keys and values in redis in javascript?

Upvotes: 3

Iurii Perevertailo
Iurii Perevertailo

Reputation: 2717

Combination of 2 requests:

import * as ioredis from 'ioredis';

const redis = new ioredis({
    port: redisPort,
    host: redisServer,
    password: '',
    db: 0
  });

const keys = await redis.collection.keys('*');
const values = await redis.collection.mget(keys);

Order will be the same for both arrays.

Upvotes: 9

Aruna
Aruna

Reputation: 12022

First of all, the issue in your question is that, inside the for loop, client.get is invoked with an asynchronous callback where the synchronous for loop will not wait for the asynchronous callback and hence the next line res.json({data:jobs}); is getting called immediately after the for loop before the asynchronous callbacks. At the time of the line res.json({data:jobs}); is getting invoked, the array jobs is still empty [] and getting returned with the response.

To mitigate this, you should use any promise modules like async, bluebird, ES6 Promise etc.

Modified code using async module,

app.get('/jobs', function (req, res) {
    var jobs = [];
    client.keys('*', function (err, keys) {
        if (err) return console.log(err);
        if(keys){
            async.map(keys, function(key, cb) {
               client.get(key, function (error, value) {
                    if (error) return cb(error);
                    var job = {};
                    job['jobId']=key;
                    job['data']=value;
                    cb(null, job);
                }); 
            }, function (error, results) {
               if (error) return console.log(error);
               console.log(results);
               res.json({data:results});
            });
        }
    });
});

But from the Redis documentation, it is observed that usage of Keys are intended for debugging and special operations, such as changing your keyspace layout and not advisable to production environments.

Hence, I would suggest using another module called redisscan as below which uses SCAN instead of KEYS as suggested in the Redis documentation.

Something like,

var redisScan = require('redisscan');
var redis     = require('redis').createClient();


redisScan({
        redis: redis,
        each_callback: function (type, key, subkey, value, cb) {
            console.log(type, key, subkey, value);
            cb();
        },
        done_callback: function (err) {
            console.log("-=-=-=-=-=--=-=-=-");
            redis.quit();
        }
    });

Upvotes: 28

rsp
rsp

Reputation: 111506

This will get all keys but with no values:

const redis = require('redis');
const client = redis.createClient();

client.keys('*', (err, keys) => {
  // ...
});

Now you need to get the values for those keys in a usual way. For example:

Promise.all(keys.map(key => client.getAsync(key))).then(values => {
  // ...
});

or with async module or in any way you like.

Upvotes: 5

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