node.js - RabbitMQ 的 AMQP (Node.js) 过早关闭连接

Question

我有以下代码，它给了我以下错误。

TypeError: Cannot read property 'assertQueue' of undefined
    at /var/www/myapp/dashboard/routes.js:195:39
    at /var/www/myapp/node_modules/amqplib/lib/callback_model.js:46:16
    at /var/www/myapp/node_modules/amqplib/lib/callback_model.js:61:10
    at /var/www/myapp/node_modules/amqplib/lib/callback_model.js:74:5

如果我注释掉 conn.close()，并且代码工作正常，并且我认为代码在执行 ch.assertQueue 之前试图过早关闭 conn。解决这个问题的最佳方法是什么？

amqp.connect('amqp://localhost', function(err, conn) {
  conn.createChannel(function(err, ch) {
    var q = 'blast_queue';
    var msg = blast.id;

    ch.assertQueue(q, {durable: true});
    ch.sendToQueue(q, new Buffer(msg), {persistent: true});
    console.log(" [x] Sent '%s'", msg);
  });
  conn.close();
});

Answer 1

发生这种情况是因为连接关闭发生在执行conn.createChannel中的回调函数之前。要修复此问题，请在回调函数内移动关闭连接的行:

amqp.connect('amqp://localhost', function(err, conn) {
  conn.createChannel(function(err, ch) {
    var q = 'blast_queue';
    var msg = blast.id;

    ch.assertQueue(q, {durable: true});
    ch.sendToQueue(q, new Buffer(msg), {persistent: true});
    console.log(" [x] Sent '%s'", msg);
    conn.close(); // <=== close connection here
  });
});