根据 Firebase 中的子子项过滤产品

问题描述

我试图弄清楚如何根据 Firebase 中的子子节点过滤产品.

I am trying to figure out how to filter products based on their sub child nodes in Firebase.

我的设置如下:

products/
     product1
        /author: 12345
        /title: "Awesome"
        /description: "more awesome"
     product2
        /author: 67890
        /title: "Awesome"
        /description: "more awesome"

如何查询 Firebase 以便仅检索它所持有的 child($productId).child(author) 等于 12345 的产品?

How can I query Firebase such that I retrieve only the products for which it holds that child($productId).child(author) equals 12345?

我尝试了以下方法，但这显然不起作用.我需要一种过滤子子项的方法:

I tried the following, but that obviously does not work. I need a way to filter on the subchild:

var ref = new Firebase(FBURL);

// Attach an asynchronous callback to read the data at our posts reference
ref.child("products").child('$productId').child('author').equalTo(12345).on("value", function(snapshot) {
      console.log(snapshot.val());
    }, function (errorObject) {
      console.log("The read failed: " + errorObject.code);
});

推荐答案

只需使用orderByChild():

ref.child("products").orderByChild('author').equalTo(12345)...

这将通过 author 属性对 products 下的每个子节点进行排序，然后仅返回值为 12345 的子节点.

This will order every child node under products by its author property and then return only the ones that have a value of 12345.

请参阅 Firebase 关于查询的文档.

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