Question

我正在构建一个Flutter应用程序并使用cloud-firestore，这是我的数据库的样子

我想要一个函数，该函数以字符串数组的形式检索集合中称为“驱动程序列表”的所有文档我已经用过的东西，但是它使它们回到了新屏幕的列表视图中

class DriverList extends StatelessWidget {@overrideWidget build(BuildContext context) {
return new StreamBuilder<QuerySnapshot>(
  stream: Firestore.instance.collection('DriverList').snapshots(),
  builder: (BuildContext context, AsyncSnapshot<QuerySnapshot> snapshot) {
    if (!snapshot.hasData) return new Text('Loading...');
    return new ListView(
      children: snapshot.data.documents.map((DocumentSnapshot document) {
        return new ListTile(
          title: new Text(document['name']),
          subtitle: new Text(document['phone']),
        );
      }).toList(),
    );
  },
);

} }

Answer 1

这还有一些其他逻辑，可以删除可能重复的记录，但是您可以使用类似以下的内容从Firestore检索数据。

我们可以访问集合引用，然后列出查询结果，然后为Firestore返回的数据创建本地模型对象，然后返回这些模型对象的列表。

if let urlString = UserDefaults.standard.string(forKey: "URL_IMAGE"),
    let retrievedURL = URL(string: urlString) {

    print("retrievedURL: \(retrievedURL)")
}

来源：https://github.com/dazza5000/austin-feeds-me-flutter/blob/master/lib/data/events_repository.dart#L33

Answer 2

    import 'package:cloud_firestore/cloud_firestore.dart';
    import 'package:flutter/material.dart';

    class LoadDataFromFirestore extends StatefulWidget {
      @override
      _LoadDataFromFirestoreState createState() => _LoadDataFromFirestoreState();
    }

    class _LoadDataFromFirestoreState extends State<LoadDataFromFirestore> {
      @override
      void initState() {
        super.initState();
        getDriversList().then((results) {
          setState(() {
            querySnapshot = results;
          });
        });
      }

      QuerySnapshot querySnapshot;
      @override
      Widget build(BuildContext context) {
        return Scaffold(
          body: _showDrivers(),
        );
      }

    //build widget as prefered
    //i'll be using a listview.builder
      Widget _showDrivers() {
        //check if querysnapshot is null
        if (querySnapshot != null) {
          return ListView.builder(
            primary: false,
            itemCount: querySnapshot.documents.length,
            padding: EdgeInsets.all(12),
            itemBuilder: (context, i) {
              return Column(
                children: <Widget>[
//load data into widgets
                  Text("${querySnapshot.documents[i].data['activation']}"),
                  Text("${querySnapshot.documents[i].data['car1']}"),
                  Text("${querySnapshot.documents[i].data['car2']}"),
                  Text("${querySnapshot.documents[i].data['car5']}"),
                  Text("${querySnapshot.documents[i].data['name']}"),
                  Text("${querySnapshot.documents[i].data['phone']}"),
                ],
              );
            },
          );
        } else {
          return Center(
            child: CircularProgressIndicator(),
          );
        }
      }

      //get firestore instance
      getDriversList() async {
        return await Firestore.instance.collection('DriversList').getDocuments();
      }
    }

Answer 3

获取一次性数据：

var collection = FirebaseFirestore.instance.collection('DriverList');
var querySnapshot = await collection.get();
for (var queryDocumentSnapshot in querySnapshot.docs) {
  Map<String, dynamic> data = queryDocumentSnapshot.data();
  var name = data['name'];
  var phone = data['phone'];
}

每次更改时获取数据，使用 StreamBuilder：

StreamBuilder<QuerySnapshot<Map<String, dynamic>>>(
  stream: FirebaseFirestore.instance.collection('DriverList').snapshots(),
  builder: (_, snapshot) {
    if (snapshot.hasError) return Text('Error = ${snapshot.error}');

    if (snapshot.hasData) {
      final docs = snapshot.data!.docs;
      return ListView.builder(
        itemCount: docs.length,
        itemBuilder: (_, i) {
          final data = docs[i].data();
          return ListTile(
            title: Text(data['name']),
            subtitle: Text(data['phone']),
          );
        },
      );
    }

    return Center(child: CircularProgressIndicator());
  },
)

如何从扑扑的火力中获取数据

3 个答案: