在Flutter中下拉至REFRESH [英] pull down to REFRESH in Flutter

问题描述

我的仪表板代码如下所示， 在这里，我在getReport方法中执行get req，我在代码中添加了RefreshIndicator，当在容器内将其下拉时应该进行刷新，在这里我调用了getData()，但是我没有得到刷新的内容，我正在在下面添加我的代码，让我知道是否在任何地方出错.

My dashboard code looks like this, Here I am doing get req in getReport method, I have added the RefreshIndicator in the code which when pulled down inside container should do the refresh, there I am calling my getData(), But I am not getting the refreshed content, I am adding my code below, let me know if anywhere I made a mistake.

在我的dashboard.dart下方

below my dashboard.dart

class Window extends StatefulWidget {
  @override
  _WindowState createState() => _WindowState();
}

class _WindowState extends State<Window> {
  Future reportList;    
  @override
  void initState() {
    super.initState();
    reportList = getReport();
  }    

  Future<void> getReport() async {
    http.Response response =
        await http.get(reportsListURL, headers: {"token": "$token"});
    switch (response.statusCode) {
      case 200: 
        String reportList = response.body;
        var collection = json.decode(reportList);
        return collection;

      case 403:
          break;

      case 401:
        return null;

      default:
        return 1;
    }
  }

  getRefreshScaffold() {
    return Center(
      child: RaisedButton(
        onPressed: () {
          setState(() {
            reportList = getReport();
          });
        },
        child: Text('Refresh, Network issues.'),
      ),
    );
  }

  getDashBody(var data) {
    double maxHeight = MediaQuery.of(context).size.height;
    return Column(
      children: <Widget>[
        Container(
          height: maxHeight - 800,
        ),
        Container(
          margin: new EdgeInsets.all(0.0),
          height: maxHeight - 188,
          child: new Center(
          child: new RefreshIndicator(          //here I am adding the RefreshIndicator
          onRefresh:getReport,                  //and calling the getReport() which hits the get api
          child: createList(context, data),
          ),),
        ),
      ],
    );
  }

  Widget createList(BuildContext context, var data) {
    Widget _listView = ListView.builder(
      itemCount: data.length,
      itemBuilder: (context, count) {
        return createData(context, count, data);
      },
    );
    return _listView;
  }

  createData(BuildContext context, int count, var data) {
    var metrics = data["statistic_cards"].map<Widget>((cardInfo) {
      var cardColor = getColorFromHexString(cardInfo["color"]);
      if (cardInfo["progress_bar"] != null && cardInfo["progress_bar"]) {
        return buildRadialProgressBar(
          context: context,
          progressPercent: cardInfo["percentage"],
          color: cardColor,
          count: cardInfo["value"],
          title: cardInfo["title"],
        );
      } else {
        return buildSubscriberTile(context, cardInfo, cardColor);
      }
    }).toList();

    var rowMetrics = new List<Widget>();
    for (int i = 0; i < metrics.length; i += 2) {
      if (i + 2 < metrics.length)
        rowMetrics.add(Row(children: metrics.sublist(i, i + 2)));
      else
        rowMetrics.add(Row(children: [metrics[metrics.length - 1], Spacer()]));
    }
    return SingleChildScrollView(
      child: LimitedBox(
        //  maxHeight: MediaQuery.of(context).size.height / 1.30,
        child: Column(
          mainAxisSize: MainAxisSize.max,
          mainAxisAlignment: MainAxisAlignment.center,
          children: rowMetrics,
        ),
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return FutureBuilder(
      future: reportList,
      builder: (BuildContext context, AsyncSnapshot snapshot) {
        switch (snapshot.connectionState) {
          case ConnectionState.none:
          case ConnectionState.waiting:
          case ConnectionState.active:
            return Center(
              child: CircularProgressIndicator(),
            );
          case ConnectionState.done:
            var data = snapshot.data;
            if (snapshot.hasData && !snapshot.hasError) {
              return getDashBody(data);
            } else if (data == null) {
              return Center(
                child: Column(
                  mainAxisSize: MainAxisSize.min,
                  children: <Widget>[
                    Text("Timeout! Log back in to continue"),
                    Padding(
                      padding: EdgeInsets.all(25.0),
                    ),
                    RaisedButton(
                      onPressed: () {
                        setState(() {
                          token = null;
                        });
                        Navigator.of(context).pushReplacement(
                          CupertinoPageRoute(
                              builder: (BuildContext context) => LoginPage()),
                        );
                      },
                      child: Text('Login Again!'),
                    ),
                  ],
                ),
              );
            } else {
              getRefreshScaffold();
            }
        }
      },
    );
  }
}

推荐答案

不确定期货，但是对于刷新指标，您必须返回空值，以便 使用类似的东西

Not sure about futures, but for refresh indicator you must return a void so Use something like

RefreshIndicator(
                onRefresh: () async  {
                  await getData().then((lA) {
                    if (lA is Future) {
                      setState(() {
                        reportList = lA;
                      });
                      return;
                    } else {
                      setState(() {
                       //error
                      });
                      return;
                    }
                  });

                  return;
                },

尝试一下，让我知道！

好吧，然后在您的刷新方法中尝试一下

Well, then just try this inside you refresh method

          setState(() {
            reportList = getReport();  
          });
          return reportList;

这篇关于在Flutter中下拉至REFRESH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IT屋！