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我是 Node.js 的新手。我正在尝试使用来自 npm 的 node-zookeeper-client（Github 链接 - https://github.com/alexguan/node-zookeeper-client）

我想了解如何一起使用此库中提供的 getChildren 和 getData 方法。（我了解这些使用回调）

目的是遍历给定路径的所有孩子，并获取所有孩子的数据并在进入下一个孩子之前将其同步打印出来。

var zookeeper = require('node-zookeeper-client');
var client = zookeeper.createClient('localhost:2181');
var path =  "/Services/Apache";
var tmpChildren = [];

function getChildren(client,path){

console.log('path value received is..', path );
client.getChildren(path, function (error, children, stats) {
    if (error) {
        console.log(error.stack);
        return;
    }

    console.log('Children are: %s', children);
    tmpChildren = String(children).split(",");
    var newPath="";

   for(var i=0; i < tmpChildren.length ; i++)
   {
      newPath = path+'/'+tmpChildren[i];
      console.log('children is %s',tmpChildren[i]);
      var str = client.getData(newPath, function(error,data){
             if (error) {
              return error.stack; 
          }
             return data ? data.toString() : undefined;

      });
      console.log('Node: %s has DATA: %s', newPath, str);
  }

}

);

}

client.once('connected', function () 
    {
    console.log('Connected to the server.');
    getChildren(client,path);


});

client.connect();

上面的代码就是我所拥有的。输出如下

Connected to the server.
path value received is.. /Services/Apache
Children are: Instance4,Instance3,Instance2,Instance1
children is Instance4
Node: /Services/Apache/Instance4 has DATA: undefined
children is Instance3
Node: /Services/Apache/Instance3 has DATA: undefined
children is Instance2
Node: /Services/Apache/Instance2 has DATA: undefined
children is Instance1
Node: /Services/Apache/Instance1 has DATA: undefined

如果您看到 DATA，它将被打印为未定义。我希望打印每个单独的子节点的正确数据而不是未定义的数据。

有人可以帮忙吗？谢谢。

PS：数据在client.getData()的函数中打印，但没有分配给变量 str。

4

1 回答 1

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getData是一个异步函数，您将无法将值返回给调用者。它将始终未定义，因为稍后会在不同的堆栈中调用回调。

要打印数据，您需要将console.log语句放入 getData 回调函数中。例如

  client.getData(newPath, function(error,data){
      if (error) {
          console.log(error.stack); 
          return;
      }

      console.log('Node: %s has DATA: %s', newPath, data ? data.toString() : '');
  });
于 2013-07-29T17:57:44.843 回答