假设嵌套的嵌入式文档结构为：

{
  "_id": ObjectId("5f1730eacdc0d437083f1522"),
  "name": "John",
  "age": 30,
  "contacts": [
    {
      "phone": "123456",
      "email": "john@example.com",
      "address": {
        "street": "123 Main Street",
        "city": "New York",
        "state": "NY",
        "country": "USA"
      }
    },
    {
      "phone": "789012",
      "email": "john@gmail.com",
      "address": {
        "street": "456 Park Avenue",
        "city": "Los Angeles",
        "state": "CA",
        "country": "USA"
      }
    }
  ]
}

遍历所有contacts中的address对象：

db.contacts.find({"name": "John"}).forEach(function(doc) {
  doc.contacts.forEach(function(contact) {
    print(contact.address)
  })
})

输出结果为：

{
  "street": "123 Main Street",
  "city": "New York",
  "state": "NY",
  "country": "USA"
}
{
  "street": "456 Park Avenue",
  "city": "Los Angeles",
  "state": "CA",
  "country": "USA"
}