流星 - 在异步调用设置会话变量 [英] Meteor - Setting Session variables in Asynchronous Calls

问题描述

我有设置Meteor.call函数内会话变量的一个问题。看来，流星不会设置会话变量，无论我问它的功能范围之外。

I have a problem with setting session variables inside of a Meteor.call function. It appears that Meteor won't set the session variables to whatever I ask it outside of the scope of the function.

Meteor.startup(function () {
  // code to run on server at startup
  // prompt for name

  var playerName = prompt("Please enter your name:", "");
  Meteor.call('createPlayer', playerName, function(error, result) {
    console.log("PLAYER_ID: " + result);
    Session.set("myPlayerID", result);
    console.log("SESSION_PLAYER_ID: " + Session.get("myPlayerID"));
  });

  console.log("SESSION_PLAYER_ID2: " + Session.get("myPlayerID"));
  Session.set("gameState", SHOW_LOBBY);
});

控制台打印出来：

The console prints out:

PLAYER_ID：正确的ID

PLAYER_ID: correct ID

SESSION_PLAYER_ID：正确的ID

SESSION_PLAYER_ID: correct ID

SESSION_PLAYER_ID2：未定义

SESSION_PLAYER_ID2: undefined

正如你所看到的，会话变量不再是功能范围之外的正确。有什么建议么？

As you can see, the session variable is no longer correct outside of the scope of the function. Any suggestions?

推荐答案

要调用的createPlayer 是异步的，所以执行的顺序将是：

The call to createPlayer is asynchronous, so the order of execution will be:

1. 提示用户


2. 开始调用的createPlayer


3. 请 myPlayerID 会话变量（SESSION_PLAYER_ID2）


4. 末梢调用的createPlayer ：将 myPlayerID 会话变量在回调

1. prompt the user
2. start the call to createPlayer
3. log myPlayerID session variable (SESSION_PLAYER_ID2)
4. finsh the call to createPlayer: set the myPlayerID session variable in the callback

由于（4）将（3）之后，您将获得执行未定义试图登录SESSION_PLAYER_ID2的时候。如果是这样的事情的唯一的事情（即没有一个bug其他地方在code），你应该能够做到在浏览器的控制台以下内容：

Because (4) will execute after (3), you will get undefined when trying to log "SESSION_PLAYER_ID2". If that's the only thing going on (i.e. there isn't a bug somewhere else in your code), you should be able to do the following in your browser console:

console.log(Session.get('myPlayerID'));

和，希望，你会得到正确的结果。因此，要回答你原来的问题：我看不出这里有什么问题 - 会话变量依然会范围外提供。这似乎只是一个异步函数的行为的误解。

And, hopefully, you will get the correct result. So to answer your original question: I don't see anything wrong here - the Session variable will still be available outside of the scope. This appears to be just a misunderstanding of the behavior of asynchronous functions.

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