問題描述

我最近詢問如何根據(jù)子屬性過濾產(chǎn)品(請參閱:根據(jù) Firebase 中的子子項過濾產(chǎn)品).

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

作為回顧，我的結(jié)構(gòu)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"

要過濾出作者為 12345 的所有產(chǎn)品，我們可以簡單地使用:

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

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

但是，當我有多個 AND 語句或多個 OR 語句時該怎么辦?

如果我想過濾掉怎么辦:

So what if I want to filter out:

• 作者為 12345 AND 類別 catA 的所有產(chǎn)品(返回 product1)

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

作者為 12345 或作者 67890 的所有產(chǎn)品(返回 product1 和 product3)

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

對于第一部分，我嘗試了:

For the first part, I tried:

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

但這不起作用(拋出錯誤You can't combine multiple orderBy calls)

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

另請參閱:https://www.firebase.com/docs/web/guide/retrieving-data.html#section-queries

推薦答案

根據(jù)我的閱讀 這里，這樣做的方法是執(zhí)行第一個查詢(最好是返回最少結(jié)果的那個)，然后在javascript中按另一個字段過濾.另一種方法，如果您經(jīng)常執(zhí)行此查詢，我建議您這樣做，是為查詢創(chuàng)建一個復合索引，例如；上面鏈接中 Frank van Puffelen 的回答舉了一個例子.

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"，我已經(jīng)找了很長時間，但沒有找到對您有幫助的東西.我建議兩個單獨的查詢.

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

這篇關于在 Firebase 中過濾多個子屬性的產(chǎn)品的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網(wǎng)！