如何将多态文档存储在Firestore的同一集合中？

{
  "type": "user",
  "name": "John Doe",
  "email": "john.doe@example.com"
}

{
  "type": "product",
  "name": "Laptop",
  "price": 999.99
}

const db = firebase.firestore();

// 查询所有用户
db.collection('items').where('type', '==', 'user').get().then(snapshot => {
  snapshot.forEach(doc => {
    console.log(doc.id, ' => ', doc.data());
  });
});

// 查询所有产品
db.collection('items').where('type', '==', 'product').get().then(snapshot => {
  snapshot.forEach(doc => {
    console.log(doc.id, ' => ', doc.data());
  });
});

{
  "id": "user-123",
  "name": "John Doe"
}

{
  "id": "user-123",
  "users": [
    {
      "name": "John Doe",
      "email": "john.doe@example.com"
    }
  ]
}

const db = firebase.firestore();

// 查询用户
db.collection('users').doc('user-123').collection('users').get().then(snapshot => {
  snapshot.forEach(doc => {
    console.log(doc.id, ' => ', doc.data());
  });
});

{
  "id": "user-123",
  "name": "John Doe"
}

{
  "id": "profile-456",
  "userId": "user-123",
  "bio": "Software Engineer"
}

const db = firebase.firestore();

// 查询用户信息
db.collection('users').doc('user-123').get().then(doc => {
  if (doc.exists()) {
    const userId = doc.id;
    return db.collection('profiles').where('userId', '==', userId).get();
  }
}).then(snapshot => {
  snapshot.forEach(doc => {
    console.log(doc.id, ' => ', doc.data());
  });
});