Node-redis: multi.hmget not working when passing in an array of hash keys.

[Jezternz]

Hi,
I am using the latest version of node-redis on npm (0.8.2 https://npmjs.org/package/redis),
Anyway when I call the below commands everything is peachy:

redisClient.hmget('{key}', ['{hashkey1}', '{hashkey2}']) => [val1, val2]
redisClient.hmget('{key}', '{hashkey1}', '{hashkey2}') => [val1, val2]
multi.hmget('{key}', '{hashkey1}', '{hashkey2}') => [val1, val2]

But when I call hmget with multi and feed an array of keys as the second paramater (below), all I get back is null.

multi.hmget('{key}', ['{hashkey1}', '{hashkey2}']) => [null]

As this is all through my code, this is rather inconvenient, it would be great if you could fix this and update npm, as I will have to revert to an older version until this is fixed.

Cheers

[brycebaril]

Hi @Jezternz -- there are some multi parser bug fixes that should go out in the next version. This may be an instance of one of the bugs that #382 will fix. You could try your example with that PR to see if it fixes your issue.

[ionian-wind]

multi.hmget('{key}', ['{hashkey1}', '{hashkey2}']) => [null]

Well, all the same for current moment. =(

The workaround is to use multi.hmget like that:
multi.hmget(['{key}', '{hashkey1}', '{hashkey2}'])

[brycebaril]

Ahh, yes, this is because the list is stringified. Multi isn't getting the same HMGET command parsing logic that you get without multi. See https://github.com/mranney/node_redis/blob/master/index.js#L968

This sort of thing is exactly one of the things I'm working on fixing in the refactor.

> c.multi().hmget("somehash", ["cat", "cow"]).exec(console.log)
send 127.0.0.1:6379 id 2: *1
$5
MULTI

send_command buffered_writes: 0  should_buffer: false
send 127.0.0.1:6379 id 2: *3
$5
hmget
$8
somehash
$7
cat,cow

send_command buffered_writes: 0  should_buffer: false
send 127.0.0.1:6379 id 2: *1
$4
EXEC

vs.

c.multi().hmget("somehash", "cat", "cow").exec(console.log)
send 127.0.0.1:6379 id 2: *1
$5
MULTI

send_command buffered_writes: 0  should_buffer: false
send 127.0.0.1:6379 id 2: *4
$5
hmget
$8
somehash
$3
cat
$3
cow

send_command buffered_writes: 0  should_buffer: false
send 127.0.0.1:6379 id 2: *1
$4
EXEC

[barisusakli]

I just ran into this and the following worked for me.

function getMultiFields(key, fields, callback) {
    var multi = redis.multi();
    multi.hmget.apply(multi, [key].concat(fields));
    multi.exec(callback);
}

[julianlam]

Oh hey @barisusakli, fancy seeing you here. Your code worked for me. (In my case, I accidentally defaulted to using null instead of multi for the thisArg in .apply(). Changing it to multi fixed it up)

[BridgeAR]

This is fixed in newer versions

[katopz]

So what final function look like? I saw

            it('returns strings for keys requested', function (done) {
                client.hmget('hash key 2', 'key 1', 'key 2', function (err, reply) {
                    assert.strictEqual(true, Array.isArray(reply));
                    assert.strictEqual(2, reply.length);
                    assert.strictEqual('val 1', reply[0]);
                    assert.strictEqual('val 2', reply[1]);
                    return done(err);
                });
            });

but not this anywhere

client.hmget('hash key 2', ['key 1', 'key 2'], function (err, reply)  {}

In my case ['key 1', 'key 2'] is need because it will be vary and I can't find the way to make it work.
Thanks

[Celadora]

@katopz I was able to use the following pattern to accomplish what you are looking for:

  // set up multi
  var multi = client.multi();

  // add each key to pipe
  for(var i = 0; i < keys.length; i++) {
    multi = multi.hgetall(keys[i]);
  }
  // execute multi
  multi.exec(function (err, replies) {
    if(err) console.error(err);
    else console.log(replies);
  });

I hope this helps you!

[coderroggie]

@katopz this is a day or two late, but i was struggling with the same problem and ended up being able to use the spread operator to make this work properly.

client.hmget('hash key 2', ...['key 1', 'key 2'], function (err, reply)  {}

Hope that helps.