如何根据 Firestore 数据库中的字段从集合中搜索文档? [英] How to search document(s) from a collection based on a Field in Firestore database?

问题描述

我正在开发一个 React Native 应用程序，我正在从 firebase 集合中获取配置文件.我想添加一个搜索功能，当我输入用户名的前 1 个或 2 个(或更多)字母并按下搜索按钮时.我应该能够获取以 1 或 2 个字母开头的用户名.

I'm working on a React Native application and I'm fetching profiles from a firebase collection. And I want to add a search functionality where when I enter even the first 1 or 2 (or more) alphabets of a username and press the search button. I should be able to fetch usernames starting with those 1 or 2 alphabets.

我确实检查了 Cloud Firestore 查询，但找不到针对我的问题的查询.

I did check Cloud Firestore queries but couldn't find one for my problem.

更新的问题:

在上面的代码中，我添加了 Renaud Tarnec 回答的以下代码.

In the above code, I'm adding the below code as answered by Renaud Tarnec.

 let queries = hashes.map(hash => rangeQueryParams(hash))
            .map(range => profiles.where('hash', '>=', range.start).where('hash', '<', range.end)
            .orderBy('displayName') // displayName is the name of Field here
            .startAt(searchString)
            .endAt(searchString + 'uf8ff')
            .get());

但这似乎不起作用.我猜这是因为范围过滤器和 orderBy 在这里位于不同的字段上.

But this doesn't seems to work. I guess it's because range filter and orderBy are on different fields here.

推荐答案

你应该结合使用 orderBy()、startAt() 和 endAt()，请参阅此处的文档:https://firebase.google.com/docs/firestore/query-data/order-limit-data?authuser=0

You should use a combination of orderBy(), startAt() and endAt(), see the documentation here: https://firebase.google.com/docs/firestore/query-data/order-limit-data?authuser=0

 var searchString = 'Sh'   //Example of value
 firebase
      .firestore()
      .collection('yourCollectioName')
      .orderBy('username')
      .startAt(searchString)
      .endAt(searchString + 'uf8ff')
      .get()
  .then(...)

查询中使用的字符 uf8ff 在 Unicode 中大多数常规字符之后，因此查询匹配所有以 searchString 开头的值.

The character uf8ff used in the query is after most regular characters in Unicode, therefore the query matches all values that start with searchString.

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