在 Firebase 中过滤多个子属性的产品

问题描述

我最近询问如何根据子属性过滤产品(请参阅:根据 Firebase 中的子子项过滤产品).

I recently asked how to filter products based on their child property (see: Filter products based on the sub child in Firebase).

作为回顾，我的结构如下所示:

As a recap my structure looks as follows:

products/
     product1
        /author: 12345
        /title: "Awesome"
        /category: "catA"
        /description: "more awesome"
     product2
        /author: 67890
        /title: "Other"
        /category: "catB"
        /description: "otherawesome"
     product3
        /author: 12345
        /title: "Billy"
        /category: "catB"
        /description: "otherawesome"

要过滤出作者为 12345 的所有产品，我们可以简单地使用:

And to filter out all products with author 12345 we can simply use:

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

但是，当我有多个 AND 语句或多个 OR 语句时该怎么办?

如果我想过滤掉怎么办:

So what if I want to filter out:

• 作者为 12345 AND 类别 catA 的所有产品(返回 product1)

• all products with author 12345 AND category catA (returns product1)

作者为 12345 或作者 67890 的所有产品(返回 product1 和 product3)

all products with author 12345 OR author 67890 (returns product1 and product3)

对于第一部分，我尝试了:

For the first part, I tried:

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

但这不起作用(抛出错误You can't combine multiple orderBy calls)

but that did not work (throws error You can't combine multiple orderBy calls)

另请参阅:https://www.firebase.com/docs/web/guide/retrieving-data.html#section-queries

推荐答案

根据我的阅读 这里，这样做的方法是执行第一个查询(最好是返回最少结果的那个)，然后在javascript中按另一个字段过滤.另一种方法，如果您经常执行此查询，我建议您这样做，是为查询创建一个复合索引，例如；上面链接中 Frank van Puffelen 的回答举了一个例子.

From what I've read here, the way to do this is to perform the first query (preferably the one that will return the fewest results), then filter by the other field in javascript. Another way to do this, and I'd recommend this if you are performing this query often, is create a compound index for the query like; the answer by Frank van Puffelen in the link above gives an example of this.

products/
     product1
        /author: 12345
        /title: "Awesome"
        /category: "catA"
        /description: "more awesome"
        /author_category: "12345_catA"
     product2
        /author: 67890
        /title: "Other"
        /category: "catB"
        /description: "otherawesome"
        /author_category: "67890_catB"
     product3
        /author: 12345
        /title: "Billy"
        /category: "catB"
        /description: "otherawesome"
        /author_category: "12345_catB"

至于或"，我已经找了很长时间，但没有找到对您有帮助的东西.我建议两个单独的查询.

As for the 'OR', I've looked for quite a while and found nothing to help you. I'd suggest two separate queries.

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