Flutter Firestore复合查询 [英] Flutter firestore compound query

问题描述

我想知道Flutter中是否有一种查询Firebase Firestore集合的方法，可以在查询中添加多个字段。我尝试了一些方法，但是我不知道该怎么做。例如：

i'd like to know if there's a way to query firebase firestore collection in Flutter adding more than one field to the query. I tried some ways but i didn't realize how to do that. For example:

CollectionReference col = Firestore.instance
    .collection("mycollection");

col.where('nome', isEqualTo: 'Tyg');
col.where('valor', isLessThan: '39');

有人，请问有办法做到吗？

Someone, please, have some way to do that? i am new in flutter and not getting the way.

推荐答案

构建Firestore查询遵循构建器模式。每次调用 where 时，它将返回一个新的查询对象。因此，您具有的代码构造了两个查询，您未分配任何内容。

Building Firestore queries follows a "builder pattern". Every time you call where it returns a new query object. So the code you have constructs two queries, that you don't assign to anything.

CollectionReference col = Firestore.instance
    .collection("mycollection");

Query nameQuery = col.where('nome', isEqualTo: 'Tyg');
Query nameValorQuery = nameQuery.where('valor', isLessThan: '39');

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