使用 Node.js 从 redis 列表中删除元素

Question

I was trying to manage a list in redis with nodejs. I am able to store list with following code :

client.rpush(['room_'+room, data.customClient], function(err, reply) {

        client.lrange('room_'+room, 0, -1, function(err, reply) {
          console.log(reply);
      });
    });

The console output is

[ 'POanqn9llyTcuIurUPAN', 'm9vd57wecp6JvtHOrRSJ' ]

Now I want to delete one key POanqn9llyTcuIurUPAN from this list. How can I do this ?

Answer 1

It can be done through lrem command. The usage to delete all the entries with that value will be:

client.lrem('room_'+room, data.customClient, 0, 'POanqn9llyTcuIurUPAN', function(err, data){
    console.log(data); // Tells how many entries got deleted from the list
});

Here 0 is a count telling delete all the entries with the value POanqn9llyTcuIurUPAN in the given list. From https://redis.io/commands/lrem the possible values of the count could be:

• count > 0: Remove elements equal to value moving from head to tail.
• count < 0: Remove elements equal to value moving from tail to head.
• count = 0: Remove all elements equal to value.

Answer 2

it can be done easily like this:

client.lrem('room_'+room, 0, 'POanqn9llyTcuIurUPAN', function(err, data){
    console.log(data); // Tells how many entries got deleted from the list
});

Answer 3

client.del('POanqn9llyTcuIurUPAN', function(err, reply) {
    console.log(reply);
});

Or to check before:

client.exists('key', function(err, reply) {
  if (reply === 1) {
    client.del('POanqn9llyTcuIurUPAN', function(err, reply) {
      console.log(reply);
    });
  }
});