Firebase转换值/外键查找

firebase.database().ref('users')
  .orderByChild('age')
  .equalTo(25)
  .once('value')
  .then((snapshot) => {
    snapshot.forEach((childSnapshot) => {
      const user = childSnapshot.val();
      const convertedValue = user.name; // 将age字段的值转换为name字段的值
      console.log(convertedValue);
    });
  });

firebase.database().ref('orders')
  .orderByChild('user_id')
  .equalTo('123456')
  .once('value')
  .then((snapshot) => {
    snapshot.forEach((childSnapshot) => {
      const order = childSnapshot.val();
      const userId = order.user_id;
      firebase.database().ref('users').child(userId).once('value')
        .then((userSnapshot) => {
          const user = userSnapshot.val();
          console.log(user);
        });
    });
  });