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firebase - 从 Firebase 读取数据 - Flutter

问题描述

我想更改String为其他内容以从 firebase 读取数据。

我有以下代码：

enum Answers{GS,FB}

String _value = ''; //Probably, String should be changed. 

void _setValue(String value) => setState(() => _value = value); ////Probably, String should be changed.

Future kaleciSec(BuildContext context) async {
    switch(
    await showDialog(
...
...
                           StreamBuilder(
      stream: Firestore.instance.collection('GS').snapshots(),
      builder: (context, snapshot){
        if(!snapshot.hasData) return Center (child: CircularProgressIndicator());
        return Column(

                crossAxisAlignment: CrossAxisAlignment.start,
          children: <Widget>[
                      ListTile(
            onTap: (){Navigator.pop(context, Answers.GS);}, //selecting GS.
            title: Text(snapshot.data.documents[0]['kaleci1'], //showing data from DB

             ),
          ),
           Divider(
                    color: Colors.grey,),

                      ListTile(
            onTap: (){Navigator.pop(context, Answers.FB);},
            title: Text(snapshot.data.documents[0]['kaleci2'],
             ),

          ],
        );


      },
    ),      
                     ],
                     ),
    )
    )    


               {
      case Answers.GS:
      _setValue('GS'); //I would like connect database here.
      break;
      case Answers.FB:
      _setValue('FB'); //I would like connect database here.
      break;

    }

我的代码工作没有错误。但是，我需要显示选择的内容。基本上，我想改成_setValue('GS');这样_setValue(snapshot.data.documents[0]['kaleci1']);。请帮我！

我在这个问题上坚持了几天。

标签： firebaseflutterdartgoogle-cloud-firestorefuture

解决方案

似乎这显示了“kaleci1”，因为_setValue(selected), 只是从数据库中读取变量的值而不是 valeu。

为了让您在那里返回值，您需要返回数据库的值并将其添加到新的（或相同的变量）中，以便您可以在_setValue()函数中使用。

我相信代码应该是这样的：

enum Answers{GS,FB}

String _value = ''; //Probably, String should be changed. 

var selected = 'kaleci1';
var valueDB;

void _setValue(String value) => setState(() => _value = value); ////Probably, String should be changed.

Future kaleciSec(BuildContext context) async {
    switch(
    await showDialog(
...
...
                           StreamBuilder(
      stream: Firestore.instance.collection('GS').snapshots(),
      builder: (context, snapshot){
        if(!snapshot.hasData) return Center (child: CircularProgressIndicator());
        return Column(

                crossAxisAlignment: CrossAxisAlignment.start,
          children: <Widget>[
                      ListTile(
            onTap: (){Navigator.pop(context, Answers.GS);}, //selecting GS.
            title: Text(snapshot.data.documents[0][selected], //showing data from DB
            valueDB = snapshot.data.documents[0][selected]
             ),
          ),
           Divider(
                    color: Colors.grey,),

                      ListTile(
            onTap: (){Navigator.pop(context, Answers.FB);},
            title: Text(snapshot.data.documents[0][selected],
            valueDB = snapshot.data.documents[0][selected]
             ),

          ],
        );


      },
    ),      
                     ],
                     ),
    )
    )    


               {
      case Answers.GS:
      _setValue(valueDB); //I would like connect database here.
      break;
      case Answers.FB:
      _setValue(valueDB); //I would like connect database here.
      break;

    }

请让我知道这是怎么回事！

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