NodeJS无法访问回调内部的变量 [英] NodeJS Can't Access Variable Inside Callback

问题描述

我认为这是异步的问题，但我不知道解决方案.

I believe this is a problem with it being async, but I do not know the solution.

    PagesController.buy = function() {

  var table="";
  Selling.find({}, function(err, res) {
    for (var i in res) {
      console.log(res[i].addr);
      table = table + "res[i].addr";
    }
  });
  this.table = table;
  console.log(table);
  this.render();
}

我的问题是，如果我尝试在函数外部访问this.table=table，则会返回undefined，并且我无法弄清楚如何在页面上显示表格.

My issue is that this.table=table is returning undefined if I try access it outside of the function, and I cannot figure out how to display the table on the page.

推荐答案

问题是Selling.find是异步的，并且可能在执行this.table = table时尚未完成.尝试以下类似的方法.

The problem is the Selling.find is asynchronous and likely isn't complete by the time the this.table = table is executed. Try something like the following.

PagesController.buy = function() {
  var that = this;
  Selling.find({}, function(err, res) {
    var table = '';
    for (var i in res) {
      console.log(res[i].addr);
      table = table + res[i].addr;
    }

    that.table = table;
    console.log(table);
    that.render();
  });
}

这将确保在获取结果并填充表之后才使用表.

That will guarantee that table isn't used until after the results have been fetched and table has been populated.

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