在Field Projection中忽略batchSize字段名称

您正确地认为驱动程序将其错误地解释为

batchSize

尽管在现代驱动程序版本中，执行此操作的正确方法是实际使用

.project()

    db.collection('collection').find()      .project({ name: 1, batchSize: 1})      .toArray();

作为完整的演示：

const mongodb = require('mongodb'),      MongoClient = mongodb.MongoClient;(async function() {  let db;  try {    db = await MongoClient.connect('mongodb://localhost/test');    // New form uses .project() as a cursor method    let result = await db.collection('collection').find()      .project({ name: 1, batchSize: 1})      .toArray();    console.log(JSON.stringify(result,undefined,2));    // Legacy form confuses this as being a legacy "cursor option"    let other = await db.collection('collection')      .find({},{ name: 1, batchSize: 1 })      .toArray();    console.log(JSON.stringify(other,undefined,2));  } catch(e) {    console.error(e)  } finally {    db.close()  }})()

产生输出：

[  {    "_id": "594baf96256597ec035df23c",    "name": "Batch 1",    "batchSize": 30  },  {    "_id": "594baf96256597ec035df234",    "name": "Batch 2",    "batchSize": 50  }][  {    "_id": "594baf96256597ec035df23c",    "name": "Batch 1",    "batchSize": 30,    "users": []  },  {    "_id": "594baf96256597ec035df234",    "name": "Batch 2",    "batchSize": 50,    "users": []  }]

如果第一个输出形式是更正的形式，则使用

.project()