变量与mongodb dotnotation [英] variable with mongodb dotnotation

问题描述

我想将mongodb文档中对象对象内的字段增加1。

I want to increase a field inside an object object inside a mongodb document by 1.

  var stuffID = 5
  collection.update({
    "id": id,
  },
  {
    '$inc': {
      'stuff.stuffID': 1
    }
  },
  function(err, doc) {
    res.end('done');
  });

我需要将那个stuffID变成一个变量。有办法吗？谢谢。

I need to make that stuffID a variable. Any way to do that? Thanks.

如果有帮助的话，这是使用node-mongodb-native。

This is using node-mongodb-native if that helps.

如果你投票给你能解释一下你不明白的东西吗？

If you're voting to close can you explain what it is you don't understand?

推荐答案

你需要分别创建你的可变键控对象，因为在ES2015之前的JS不允许除了对象文字语法中的常量字符串之外的任何内容：

You need to create your variably-keyed object separately, because JS before ES2015 doesn't permit anything other than constant strings in object literal syntax:

var stuffID = 5
var stuff = {};                 // create an empty object
stuff['stuff.' + stuffID] = 1;  // and then populate the variable key

collection.update({
    "id": id,
}, {
    "$inc": stuff               // pass the object from above here
}, ...);

编辑，现在可以将表达式用作关键字在对象文字中，使用 [expr]：value 语法，在这种情况下也使用ES2015反引号字符串插值：

EDIT in ES2015, it's now possible to use an expression as a key in an object literal, using [expr]: value syntax, and in this case also using ES2015 backtick string interpolation:

var stuffID = 5;
collection.update({
    "id": id,
}, {
    "$inc": {
        [`stuff.${stuffID}`]: 1
    }
}, ...);

以上代码适用于Node.js v4 +

The code above works in Node.js v4+

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