在Flutter上进行Firestore查询

问题描述

如何在FlutterFire中使用.where()对Firestore执行查询?因为文档和示例未涵盖此内容，所以我感到困惑.我在这里还没有找到其他问题，所以希望我不要重复.

How can I use the .where() in FlutterFire to perform queries for Firestore? Because the docs and example doesn't cover this I'm confused. I haven't found other questions on this here so I hope I'm not asking duplicate.

推荐答案

下面的示例遍历集合字段"中的每个文档，并根据"grower"进行过滤.没有关于它的文档，但是您可以检查源代码.

Example below go through every document in the collection 'fields', and filter on 'grower`. There is no documentation on that, but you may check the source code.

import 'package:cloud_firestore/cloud_firestore.dart';

Firestore.instance.collection('fields').where('grower', isEqualTo: 1)
    .snapshots().listen(
          (data) => print('grower ${data.documents[0]['name']}')
    );

从源代码:

  Query where(
    String field, {
    dynamic isEqualTo,
    dynamic isLessThan,
    dynamic isLessThanOrEqualTo,
    dynamic isGreaterThan,
    dynamic isGreaterThanOrEqualTo,
    bool isNull,
  }) {..}

这篇关于在Flutter上进行Firestore查询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！