带列表的Redis发布/订阅

Question

I'm using Redis with Node.js.

client = redis.createClient();
client.subscribe("__keyspace@0__:url_set");
client.on("message",function(channel, message) {
    client.on('connect', function() {
        client.lrange('url_list',0,-1,function(err3, reply3) {
            console.log(reply3);
        });
        client.smembers('url_set',function(err4, reply4) {
            console.log(reply4);
        });
    });
});

Here reply3 and reply4 are undefined . Are lrange() and smembers() not allowed within a pub sub "on message" block?

Answer 1

Yes, regular commands are not allowed when a client is in subscriber mode. Create a another client for regular commands.

var client2 = redis.createClient();

use client2 for lrange() and smembers() .

Refer node-redis doc :

When a client issues a SUBSCRIBE or PSUBSCRIBE, that connection is put into a "subscriber" mode. At that point, only commands that modify the subscription set are valid. When the subscription set is empty, the connection is put back into regular mode.

If you need to send regular commands to Redis while in subscriber mode, just open another connection.