如何获取Firebase Firestore Android中某个字段的值? [英] How to get value of some field in firebase firestore android?
问题描述
像上一个问题一样,我想获取Firebase Firestore中某个字段的值,而不是使用 DocumentSnapshot
Like upper question, i want to get value of some field in firebase firestore instead of all document with DocumentSnapshot
在SQL SELECT col_1, col_2, col_3 FROM table_name
我该怎么办?
谢谢您的帮助.
推荐答案
Cloud Firestore客户端SDK始终读取并返回完整文档.无法读取文档中字段的子集.
The Cloud Firestore client-side SDKs always read and returns full documents. There is no way to read a subset of the fields in a document.
您可以检索整个文档,然后处理DocumentSnapshot
以仅使用您感兴趣的字段.但这意味着您使用的带宽超出了需要.如果您的应用经常出现这种情况,请考虑创建一个辅助集合,其中每个文档仅包含您感兴趣的字段.
You can retrieve the entire document, and then process the DocumentSnapshot
to just use the fields you're interested. But this means you're using more bandwidth than needed. If this is a regular occurrence for your app, consider creating a secondary collection where each document contains just the fields you're interested in.
这篇关于如何获取Firebase Firestore Android中某个字段的值?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!