MongoDB 查询帮助 - 查询子对象中任意键的值

MongoDB是一种非关系型数据库，广泛应用于大数据存储和处理。在进行数据查询时，经常会遇到需要查询子对象中任意键的值的情况。本文将介绍如何使用MongoDB的查询帮助功能来实现这一功能，并附带案例代码。

json
{
  "_id": 1,
  "name": "John",
  "address": {
    "street": "123 Main St",
    "city": "New York",
    "state": "NY"
  }
}

javascript
db.users.find({ "address.city": "New York" })

javascript
const MongoClient = require('mongodb').MongoClient;
const url = 'mongodb://localhost:27017';
const dbName = 'mydb';
MongoClient.connect(url, function(err, client) {
  console.log("Connected successfully to server");
  const db = client.db(dbName);
  // 在这里执行查询操作
});

javascript
const collection = db.collection('users');
const documents = [
  {
    "_id": 1,
    "name": "John",
    "address": {
      "street": "123 Main St",
      "city": "New York",
      "state": "NY"
    }
  },
  {
    "_id": 2,
    "name": "Jane",
    "address": {
      "street": "456 Elm St",
      "city": "Los Angeles",
      "state": "CA"
    }
  },
  // 更多示例数据...
];
collection.insertMany(documents, function(err, result) {
  console.log("Inserted documents into the collection");
  client.close();
});

javascript
const collection = db.collection('users');
collection.find({ "address.city": "New York" }).toArray(function(err, docs) {
  console.log("Found the following documents:");
  console.log(docs);
  client.close();
});