在 NodeJS 中，如何从 mongodb 输出具有不同字段名称的结果?

2022-01-20 00:00:00 mongodb aggregation-framework node.js javascript monk

我正在使用 nodejs 查询 mongodb 并希望输出带有自定义字段名称的 json.

I'm using nodejs to query mongodb and want to output json with customized field names.

例如，可能是来自 MongoDB 的原始 json

For example, original json from MongoDB maybe

    {id:1, text:"abc"}

我想把它输出为 

    {ObjectID:1, DisplayText:"abc"};

我了解 MongoDB 在其聚合框架中有 $project 运算符，但不确定如何在 NodeJS 中使用它们.

I understand MongoDB has the $project operator in its aggregate framework but not sure how to use them in NodeJS.

我使用的 mongodb nodejs 包是

The mongodb nodejs packages I'm using are 

    var mongo = require('mongodb');
    var monk = require('monk');
    var db = monk('server:port/mydb');

感谢您对此的任何建议.

Appreciate any advice on this.

推荐答案

如果您使用的是和尚，那么您可以通过 .col 访问器访问底层节点本机驱动程序集合类型在您选择的集合对象上:

If you are using monk as you appear to be then you can access the underlying node native driver collection type via the .col accessor on your selected collection object:

  var db = require('monk')('localhost/test')
    , collection = db.get('example');

  collection.col.aggregate(
    [
      { "$project": {
        "_id": 0,
        "ObjectID": "$_id",
        "DisplayText": "$text"
      }}
    ],
    function(err,result) {

      console.log( JSON.stringify( result, undefined, 4 ) );

    }
  );

注意 .aggregate() 以这种方式检索的不会像标准的僧侣集合对象那样包装在承诺对象中.但至少这向您展示了如何访问和使用 $project 重新塑造您的文档.

Note that methods such as .aggregate() retrieved in this way are not wrapped in the promise object as the standard monk collection objects are. But at least this shows you how to access and use $project to re-shape your document.

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