鉴于以下数据结构:
{
"comments" : {
"-JcBbk64Gpm1SKoFHv8b" : {
"content" : "blah",
"createdAt" : 1417550954985,
"link" : "http%3A%2F%2Flocalhost%3A3000%2F",
"recommendedCount" : 0,
"replies" : {
"-JcBbk8gF_nQ_vjwag61" : true
},
"replyCount" : 1
},
"-JcBbk8gF_nQ_vjwag61" : {
"content" : "blah blah",
"createdAt" : 1417550955151,
"link" : "http%3A%2F%2Flocalhost%3A3000%2F",
"recommendedCount" : 0,
"replyCount" : 1,
"replyToComment" : "-JcBbk64Gpm1SKoFHv8b"
}
},
"links" : {
"http%3A%2F%2Flocalhost%3A3000%2F" : {
"author" : 5,
"commentCount" : 2,
"comments" : {
"-JcBbk64Gpm1SKoFHv8b" : true,
"-JcBbk8gF_nQ_vjwag61" : true
},
"createdAt" : 1417550954931,
"ratingCount" : 2,
"recommendedCount" : 32,
"score" : 91,
"title" : "A Christian vs. an Atheist: Round 2",
"url" : "http://localhost:3000/"
}
}
}
我想检索给定链接的所有注释,并按相反的时间顺序对它们进行排序。我已经做到了这一点,但我无法弄清楚如何进行反向排序,因为我已经使用orderByChild通过链接缩小结果范围:
ref.orderByChild('link').equalTo(currentLink).on('value', function (snap) {
console.log(snapshot.val());
});
如果我第二次调用orderByChild():
ref.orderByChild('link').equalTo(currentLink).orderByChild('createdAt').on('value', function (snap) {
console.log(snapshot.val());
});
它失败并显示以下错误消息:
未捕获错误:Query.orderByChild:您无法合并多个orderBy调用。
我很难过。有什么建议吗?
答案 0 :(得分:-1)
我在firebase项目中遇到了同样的问题,我解决了这个问题。 请看一下。
var formRef = firebase.child('links').child(currentLink);
formRef.orderByChild('createdAt').on('value', function (snap) {
console.log(snapshot.val());
});
它会起作用。 最诚挚的问候。