如何在MongoDB中搜索父对象中的子对象？

// 假设有一个名为parents的集合，包含父对象和其子对象
{
  _id: ObjectId("60aee1d5f5f39e729a74589c"),
  name: "父对象1",
  children: [
    { name: "子对象1", age: 10 },
    { name: "子对象2", age: 15 },
    { name: "子对象3", age: 20 }
  ]
},
{
  _id: ObjectId("60aee1d5f5f39e729a74589d"),
  name: "父对象2",
  children: [
    { name: "子对象4", age: 25 },
    { name: "子对象5", age: 30 },
    { name: "子对象6", age: 35 }
  ]
}

// 使用$elemMatch操作符查询父对象中age为20的子对象
db.parents.find({ children: { $elemMatch: { age: 20 } } })

// 输出结果
{
  _id: ObjectId("60aee1d5f5f39e729a74589c"),
  name: "父对象1",
  children: [
    { name: "子对象1", age: 10 },
    { name: "子对象2", age: 15 },
    { name: "子对象3", age: 20 }
  ]
}