查询Firebase实时数据库中的嵌套数据以填充ListView

{
  "users": {
    "user1": {
      "name": "Alice",
      "age": 30,
      "posts": {
        "post1": {
          "title": "First Post",
          "content": "This is my first post."
        },
        "post2": {
          "title": "Second Post",
          "content": "This is my second post."
        }
      }
    },
    "user2": {
      "name": "Bob",
      "age": 25,
      "posts": {
        "post1": {
          "title": "Hello World",
          "content": "My first post."
        }
      }
    }
  }
}

// Initialize Firebase
const firebaseConfig = {
  apiKey: "YOUR_API_KEY",
  authDomain: "YOUR_PROJECT_ID.firebaseapp.com",
  databaseURL: "https://YOUR_PROJECT_ID.firebaseio.com",
  projectId: "YOUR_PROJECT_ID",
  storageBucket: "YOUR_PROJECT_ID.appspot.com",
  messagingSenderId: "YOUR_MESSAGING_SENDER_ID",
  appId: "YOUR_APP_ID"
};

firebase.initializeApp(firebaseConfig);
const database = firebase.database();

// Query nested data
database.ref('users').once('value', (snapshot) => {
  const users = snapshot.val();
  const posts = [];

  for (const userId in users) {
    const userPosts = users[userId].posts;
    for (const postId in userPosts) {
      posts.push(userPosts[postId]);
    }
  }

  // Now you have an array of posts to populate your ListView
  populateListView(posts);
});

function populateListView(posts) {
  const listView = document.getElementById('listView');
  posts.forEach(post => {
    const listItem = document.createElement('li');
    listItem.innerHTML = `<strong>${post.title}</strong><p>${post.content}</p>`;
    listView.appendChild(listItem);
  });
}