Question

在link的回答中，为了保持用户数量，它会消耗：当客户端在该函数的承诺中创建用户以返回更新计数的事务时。

以下是firebase 3.0中的类似代码段

数据库结构是：

- users
-- someuid
--- displayName: 'Dale'
- usersCount
-- count: 1
-- users
--- someuid : true

<script src="https://www.gstatic.com/firebasejs/3.6.1/firebase.js">

</script>
<script>
  // Initialize Firebase
  var config = {
    ..
  };
  firebase.initializeApp(config);


  function createNewAccount() {
    return firebase.auth().signInAnonymously()
      .then(createUserAccountData)
      .then(updateUser);
  }

  function updateUser() {
    console.log('update user count');
    var user = firebase.auth().currentUser;
    var ref = firebase.database().ref('/usersCount');
    var uid = user.uid;
    return ref.transaction(function(post) { 
      if(post) {
        if(post.users && post.users[uid]) {
        } else {
          post.count++;
          if(!post.users) {
            post.users = {};
          }
          post.users[uid] = true;
        }
      }
      return post;
    })
  }

  /**
   * @return {User|fasle}
   */
  function getUserObjectForDb (user) {
    console.log('get user obj');
    if(!user) return false;
    return {
      displayName: user.displayName || user.uid || false,
      email: user.email || false,
      arbitraryData: 'foo'
    }
  }

  /**
   * Create a user account given a firebase user object.
   * @param {Object} result 
   */ 
  function createUserAccountData(result) {
    console.log('create user account data');
    var uid = result && result.uid || false
    if(!uid) return false;

    var user = getUserObjectForDb(result);

    var path = 'users/' + uid;
    var ref = firebase.database().ref(path);
    return ref.set(user);
  }

</script>


<button onclick="createNewAccount()">Create new account</button>

用户使用firebas.auth创建一个帐户然后，事务将用户详细信息添加到用户并递增usersCount

如何使这样的事情变得安全。如何才能信任客户更新计数器？

Firebase总用户数和计数器一般

0 个答案: