是否可以将额外的参数传递给猫鼬更新回调 [英] Is it possible to pass an extra parameter to a mongoose update callback

问题描述

我有猫鼬更新呼叫，想传递一个额外的参数...就像这样:

I have mongoose update call and would like to pass an extra parameter...like so:

试图通过 isLoopOver

UserInfo.update({_id: userInfo._id}, {'value': someval}, function(err, numAffected, isLoopOver ) {
    console.log('IsLoopOver ' + JSON.stringify(isLoopOver) );
    if (isLoopOver){
        doSomething(isLoopOver);
    }
});

尝试了上述操作，但在回调中得到了一个对象，如下所示:

Tried the above but I get an object (inside the callback) as below:

{"updatedExisting":true,"n":1,"connectionId":117,"err":null,"ok":1}

不知道为什么它显示了mongo的状态.

No idea why it is showing the status from mongo.

问题:如何通过回调传递一个额外的参数?

Question: How can I pass an extra parameter thru the callback?

推荐答案

常见方法是:

var isLoopOver = false;
UserInfo.update({_id: userInfo._id}, {'value': someval}, function(err, numAffected) {
    console.log('IsLoopOver ' + JSON.stringify(isLoopOver) );
    if (isLoopOver){
        doSomething(isLoopOver);
    }
});

如果您担心某些代码会在调用update的回调函数之前更改isLoopOver的值，请使用以下代码:

If you are worried about some code will change the value of isLoopOver before the update's callback function being called, using the following code:

(function (isLoopOver) {
  UserInfo.update({_id: userInfo._id}, {'value': someval}, function(err, numAffected) {
      console.log('IsLoopOver ' + JSON.stringify(isLoopOver) );
      if (isLoopOver){
          doSomething(isLoopOver);
      }
  });
}(isLoopOver));

isLoopOver变量显示mongo状态的原因是在回调函数中，isLoopOver是形式参数而不是实际参数.

The reason why your isLoopOver variable is showing the status from mongo is that in the callback function, the isLoopOver is a formal parameter instead of a actual parameter.

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