如何实施滑动以删除列表视图以从Firestore中删除数据 [英] How to implement a swipe to delete listview to remove data from firestore

问题描述

我对扑镖和飞镖很陌生，所以这可能是一个基本问题.但是，我想知道的是如何在列表视图中实现滑动删除方法以从Firestore中删除数据.

我尝试使用Dissmissible函数，但是我不了解如何显示列表，而且我似乎也无法理解如何删除所选数据.

这是我的飞镖代码

  Widget build(BuildContext context){返回新的脚手架(resizeToAvoidBottomPadding:否，appBar:新的AppBar(centerTitle:正确，automaticImplyLeading:否，标题:行(mainAxisAlignment:MainAxisAlignment.spaceBetween，子项:< Widget> [Text("INVENTORY"，textAlign:TextAlign.center，)，新的IconButton(图标:图标(Icons.home，颜色:黑色.)，onPressed:(){Navigator.push(语境，SlideLeftRoute(widget:MyHomePage())，);})])，)，正文:ListPage()，);}}ListPage类扩展StatefulWidget {@override_ListPageState createState()=>_ListPageState();}类_ListPageState扩展了State< ListPage>{未来的getPosts()异步{var firestore = Firestore.instance;QuerySnapshot gn =等待firestore.collection(库存").orderBy(名称"，降序:false).getDocuments();返回gn.documents;}@override窗口小部件build(BuildContext context){返回容器(子代:FutureBuilder(未来:getPosts()，生成器:(_，快照){if(snapshot.connectionState == ConnectionState.waiting){退货中心(子级:Text("Loading")，);}别的{返回ListView.builder(itemCount:snapshot.data.length，itemBuilder:(_，索引){返回EachList(snapshot.data [index] .data ["Name"].toString()，snapshot.data [index] .data ["Quantity"]);});}})，);}}class EachList扩展StatelessWidget {最终的String详细信息；最终的字符串名称；EachList(this.name，this.details);@override窗口小部件build(BuildContext context){//TODO:实现构建退回新卡(孩子:新货柜(填充:EdgeInsets.all(8.0)，子级:新行(mainAxisAlignment:MainAxisAlignment.spaceBetween，子代:< Widget> [新行(子代:< Widget> [new CircleAvatar(child:new Text(name [0] .toUpperCase()))，新的填充(padding:EdgeInsets.all(10.0))，新的Text(名称，样式:TextStyle(fontSize:20.0)，)，]，)，新的Text(详细信息，样式:TextStyle(fontSize:20.0))]，)，)，);}} 

解决方案

您应该使用Dismissible小部件.我将其用于从Firestore检索的收件箱列表.在您的EachList内返回类似这样的内容

 返回可撤销(方向:DismissDirection.startToEnd，resizeDuration:持续时间(毫秒:200)，键:ObjectKey(snapshot.documents.elementAt(index))，onDismissed :(方向){//TODO:实现删除功能，并在需要时检查方向_deleteMessage(index);}，背景:容器(填充:EdgeInsets.only(左:28.0)，对齐方式:AlignmentDirectional.centerStart，颜色:Colors.red，子代:Icon(Icons.delete_forever，颜色:Colors.white，)，)，//secondaryBackground:...，孩子: ...，);}); 

重要提示:要删除列表项，您还需要从快照列表中删除该项，而不仅是从firestore中删除:

  _deleteMessage(index){//TODO:此处从Firestore中删除，然后更新您的本地快照列表setState((){snapshot.documents.removeAt(index);});} 

此处是文档:执行滑动以关闭

下面是Flutter团队的视频:本周小部件-Dismissilbe

Im very new to flutter and dart so this might be a basic question. However, what I would like to know is how to implement a swipe to delete method in a listview to delete data from firestore too.

I tried using the Dissmissible function but i dont understand how to display the list and I cant seem to understand how to remove the selected data as well.

This here is my dart code

Widget build(BuildContext context) {
return new Scaffold(
  resizeToAvoidBottomPadding: false,
  appBar: new AppBar(
    centerTitle: true,
    automaticallyImplyLeading: false,
    title: Row(mainAxisAlignment: MainAxisAlignment.spaceBetween,children: 
<Widget>[
      Text("INVENTORY",textAlign: TextAlign.center,) ,new IconButton(
          icon: Icon(
            Icons.home,
            color: Colors.black,
          ),
          onPressed: () {
            Navigator.push(
              context,
              SlideLeftRoute(widget: MyHomePage()),
            );
          })]),
  ),body: ListPage(),
);
  }
}

 class ListPage extends StatefulWidget {
   @override
  _ListPageState createState() => _ListPageState();
  }

class _ListPageState extends State<ListPage> {

Future getPosts() async{
var firestore = Firestore.instance;

QuerySnapshot gn = await 
firestore.collection("Inventory").orderBy("Name",descending: 
false).getDocuments();

return gn.documents;

}

@override
Widget build(BuildContext context) {
return Container(
  child: FutureBuilder(
      future: getPosts(),
      builder: (_, snapshot){
    if(snapshot.connectionState == ConnectionState.waiting){
      return Center(
        child: Text("Loading"),
      );
    }else{

      return ListView.builder(
          itemCount: snapshot.data.length,
          itemBuilder:(_, index){
            return EachList(snapshot.data[index].data["Name"].toString(), 
snapshot.data[index].data["Quantity"]);
          });
    }
  }),
 );
 }
}


class EachList extends StatelessWidget{
final String details;
final String name;
EachList(this.name, this.details);
@override
 Widget build(BuildContext context) {
// TODO: implement build
return new Card(
  child:new Container(
    padding: EdgeInsets.all(8.0),
    child: new Row(
      mainAxisAlignment: MainAxisAlignment.spaceBetween,
      children: <Widget>[
        new Row(
          children: <Widget>[
            new CircleAvatar(child: new Text(name[0].toUpperCase()),),
            new Padding(padding: EdgeInsets.all(10.0)),
            new Text(name, style: TextStyle(fontSize: 20.0),),
          ],
        ),
        new Text(details, style: TextStyle(fontSize: 20.0))
      ],
    ),
  ),
);
  }

}

解决方案

You should use Dismissible widget. I used it for an inbox list retrieved from Firestore. Inside your EachList return something like this

return Dismissible(
        direction: DismissDirection.startToEnd,
        resizeDuration: Duration(milliseconds: 200),
        key: ObjectKey(snapshot.documents.elementAt(index)),
        onDismissed: (direction) {
          // TODO: implement your delete function and check direction if needed
          _deleteMessage(index);
        },
        background: Container(
          padding: EdgeInsets.only(left: 28.0),
          alignment: AlignmentDirectional.centerStart,
          color: Colors.red,
          child: Icon(Icons.delete_forever, color: Colors.white,),
        ),
        // secondaryBackground: ..., 
        child: ...,
      );

    });

IMPORTANT: in order to remove the list item you'll need to remove the item from the snapshot list as well, not only from firestore:

_deleteMessage(index){
  // TODO: here remove from Firestore, then update your local snapshot list
  setState(() {
    snapshot.documents.removeAt(index);
  });
}

Here the doc: Implement Swipe to Dismiss

And here a video by Flutter team: Widget of the week - Dismissilbe

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