Javascript引用它自己的对象内部的值

Question

I have a config file for my Node.js application which looks like this:

// Development specific configuration
// ==================================
module.exports = {

....

  ip: "localhost",
  //Rabbit MQ
  rabbitmq: {
    username: 'foo',
    password: 'bar',
    ip: 'amqp://'+this.username+':'+this.password+'@rabbitmq',
    queues: {
      name: 'foo'
    }
  }, 
....

};

Here is what the module looks like where I use this config file:

var config = require ('../../config/environment');
this.con = amqp.connect (config.rabbitmq.ip);

I am getting undefined for the username and password:

amqp://undefined:undefined@rabbitmq

I have tried multiple ways such as:

1. Creating getter functions inside the object like this:

    rabbitmq: { username: 'foo', password: 'bar', getUsername: function (){ return this.username; }, getpassword: function (){ return this.password; }, ip: 'amqp://'+this.getUsername()+':'+this.getpassword()+'@rabbitmq', 

2. Created a self value and assign 'this' and reference it:

    self: this, ... ip: 'amqp://'+self.rabbitmq.username+':'+self.rabbitmq.password+'@rabbitmq', 

   ..

I cannot get the scope to properly work. Am I missing something basic? How can I make this happen? Please help.

Answer 1

This will work:

var username = 'foo';
var password = 'bar';

module.exports = {
  ip: "localhost",
  //Rabbit MQ
  rabbitmq: {
    username: username,
    password: password,
    ip: 'amqp://'+username+':'+password+'@rabbitmq',
    queues: {
      name: 'foo'
    }
  }
};

Answer 2

You can do something like this:

var config = {
    ip : "localhost", //Rabbit MQ
    rabbitmq : {
        username : 'foo',
        password : 'bar',
        queues : {
            name : 'foo'
        }
    }
};

config is now declared in module scope so you can reuse its values

config.rabbitmq.ip = 'amqp://' + config.rabbitmq.username + ':' + config.rabbitmq.password + '@rabbitmq';
module.exports = config;