插入sqlite颤动而不冻结界面 [英] Insert sqlite flutter without freezing the interface

问题描述

我正在尝试使用flutter在sqlite内存数据库中插入很多行(大约12k或更多).

我从API获取数据并使用计算函数来处理来自Json的数据.现在，我需要将这些数据添加到内存中的数据库中，以便使用批处理事务.

  batchInsertEventSong(List< EventSong>行)异步{数据库db =等待instance.database;db.transaction((txn)异步{批次批次= txn.batch();用于(成排的var歌曲){Map< String，dynamic>行= {DatabaseHelper.columnIdSong:song.id，DatabaseHelper.columnTitle:song.title，DatabaseHelper.columnInterpreter:歌曲.解释器};batch.insert(表格，行);}batch.commit();}} 

但是此函数在插入过程中阻止了我的UI，我也尝试了计算，但是无法传递类db或类批处理.我没有弄清楚如何在另一个线程中执行此过程，或者(因为我不能使用隔离)在不阻塞我的UI的情况下执行.

有什么建议吗?

解决方案

2020年5月15日至15日

这行不通，请参阅:

• 步骤1:将您的方法设为静态并使其无效

   静态batchInsertEventSong(List< EventSong>行){数据库db =等待instance.database;db.transaction((txn)异步{批次批次= txn.batch();用于(成排的var歌曲){Map< String，dynamic>行= {DatabaseHelper.columnIdSong:song.id，DatabaseHelper.columnTitle:song.title，DatabaseHelper.columnInterpreter:歌曲.解释器};batch.insert(表格，行);}batch.commit();}} 

  第2步:创建新方法(通常但并非必需，为同名添加Async)

   将来的batchInsertEventSongAsync(List< EventSong>行){} 

  第3步:使用您的方法static调用compute并返回

   返回计算(batchInsertEventSong，行); 

  ---

  步骤[1,2,3]代码审核

   将来的batchInsertEventSongAsync(List< EventSong>行){返回compute(_batchInsertEventSong，行)；}静态_batchInsertEventSong(List< EventSong>行){数据库db =等待instance.database;db.transaction((txn)异步{批次批次= txn.batch();用于(成排的var歌曲){Map< String，dynamic>行= {DatabaseHelper.columnIdSong:song.id，DatabaseHelper.columnTitle:song.title，DatabaseHelper.columnInterpreter:歌曲.解释器};batch.insert(表格，行);}batch.commit();}} 

  ---

  完整代码

    import'dart:async';导入'package:flutter/foundation.dart';导入'package:flutter/material.dart';void main()=>runApp(MyApp());MyApp类扩展了StatelessWidget {//此小部件是您的应用程序的根.@override窗口小部件build(BuildContext context){返回MaterialApp(标题:"Flutter演示"，主题:ThemeData(primarySwatch:Colors.blue，)，主页:脚手架(正文:MyHomePage(标题:"Flutter演示首页"))，);}}类MyHomePage扩展了StatefulWidget {MyHomePage({Key key，this.title}):超级(key:key);最终的字符串标题；@override_MyHomePageState createState()=>_MyHomePageState();}类_MyHomePageState扩展State< MyHomePage>{@override窗口小部件build(BuildContext context){返回脚手架(appBar:AppBar(标题:文本(widget.title)，)，身体:中心(子:列(mainAxisAlignment:MainAxisAlignment.center，子代:< Widget> [FlatButton.icon(图标:Icon(Icons.backup)，标签:文字(长时间使用")，onPressed:()异步{var rows =等待RsetApi.getRawsAsync();等待Database._saveRaws(rows);}，)，FlatButton.icon(图标:Icon(Icons.backup)，标签:文字("Short Opreation")，onPressed:(){Scaffold.of(context).hideCurrentSnackBar();Scaffold.of(context).showSnackBar(new SnackBar(内容:new Text(DateTime.now().toIso8601String())，))；}，)，]，)，)，);}}类RsetApi {静态Future< List< EventSong>>getRawsAsync(){返回compute(_getRaws，null);}静态List< EventSong>_getRaws(pram1){var rows = List< EventSong>();对于(var i = 1; i< 12000; i ++){rows.add(EventSong(i));print(获取原始文件" +(i/12000).toString())；}返回行；}}类数据库{静态Future saveRawsAsync(List< EventSong>行){返回compute(_saveRaws，行);}静态_saveRaws(List< EventSong>行){for(var i = 1; i< rows.length; i ++){print(保存原始数据" +(i/rows.length).toString());}}}EventSong类{int id;EventSong(this.id);} 

  参考:

  • 解析JSON在后台-Flutter

  非重要引用:

  • Dart/Flutter:转换时间戳-堆栈溢出

  • 显示小吃店-Flutter

  • sdk/文件.dart at 1c4ad14fa3a0a1d5ecea10e3b04befecee3ffbcb·dart-lang/sdk

  • sdk/file_impl.dart at 1c4ad14fa3a0a1d5ecea10e3b04befecee3ffbcb·dart-lang/sdk

  • 搜索·readAsLinesSync

  I'm trying to insert a lot of rows (about 12k or more) in a sqlite memory database using flutter.

  I get data from the API and use a compute function in order to process data from Json. Now I need to add these data to a database in memory, in order to do so I use a transaction with a batch.

  batchInsertEventSong(List<EventSong> rows) async {
     Database db = await instance.database;
     db.transaction((txn) async {
        Batch batch = txn.batch();
        for (var song in rows) {
           Map<String, dynamic> row = {
             DatabaseHelper.columnIdSong: song.id,
             DatabaseHelper.columnTitle: song.title,
             DatabaseHelper.columnInterpreter: song.interpreter
           };
           batch.insert(table, row);
         }
        batch.commit();
     }
  }
  

  But this function is blocking my UI during insertions, I tried also with compute but I can't pass the class db or the class batch. I hadn't clear how to execute this process in another thread or (since I can't use isolates) executing without blocking my UI.

  Any advice?

  解决方案

  Update 2020 - 05 - 15

  this will not work see :

  • Unable to call a platform channel method from another isolate · Issue #13937 · flutter/flutter

  ---

  Note : full code available on the end

  Step 1 : make your method static and make it void

    static batchInsertEventSong(List<EventSong> rows) {
      Database db = await instance.database;
      db.transaction((txn) async {
          Batch batch = txn.batch();
          for (var song in rows) {
              Map<String, dynamic> row = {
              DatabaseHelper.columnIdSong: song.id,
              DatabaseHelper.columnTitle: song.title,
              DatabaseHelper.columnInterpreter: song.interpreter
              };
              batch.insert(table, row);
          }
          batch.commit();
      }
    }
  

  Step 2 : create new method (usually but not required add Async for the same name)

    Future batchInsertEventSongAsync(List<EventSong> rows) {
  
    }
  

  Step 3 : call compute with your method static and return

    return compute(batchInsertEventSong, rows);
  

  ---

  Step [1,2,3] code review

    Future batchInsertEventSongAsync(List<EventSong> rows) {
      return compute(_batchInsertEventSong, rows);
    }
  
    static _batchInsertEventSong(List<EventSong> rows) {
      Database db = await instance.database;
      db.transaction((txn) async {
          Batch batch = txn.batch();
          for (var song in rows) {
              Map<String, dynamic> row = {
              DatabaseHelper.columnIdSong: song.id,
              DatabaseHelper.columnTitle: song.title,
              DatabaseHelper.columnInterpreter: song.interpreter
              };
              batch.insert(table, row);
          }
          batch.commit();
      }
    }
  

  ---

  Full Code

  import 'dart:async';
  import 'package:flutter/foundation.dart';
  import 'package:flutter/material.dart';
  
  void main() => runApp(MyApp());
  
  class MyApp extends StatelessWidget {
    // This widget is the root of your application.
    @override
    Widget build(BuildContext context) {
      return MaterialApp(
        title: 'Flutter Demo',
        theme: ThemeData(
          primarySwatch: Colors.blue,
        ),
        home: Scaffold(body: MyHomePage(title: 'Flutter Demo Home Page')),
      );
    }
  }
  
  class MyHomePage extends StatefulWidget {
    MyHomePage({Key key, this.title}) : super(key: key);
  
    final String title;
  
    @override
    _MyHomePageState createState() => _MyHomePageState();
  }
  
  class _MyHomePageState extends State<MyHomePage> {
    @override
    Widget build(BuildContext context) {
      return Scaffold(
        appBar: AppBar(
          title: Text(widget.title),
        ),
        body: Center(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              FlatButton.icon(
                icon: Icon(Icons.backup),
                label: Text("Long Opreation"),
                onPressed: () async {
                  var rows = await RsetApi.getRawsAsync();
                  await Database._saveRaws(rows);
                },
              ),
              FlatButton.icon(
                icon: Icon(Icons.backup),
                label: Text("Short Opreation"),
                onPressed: () {
                  Scaffold.of(context).hideCurrentSnackBar();
                  Scaffold.of(context).showSnackBar(new SnackBar(
                    content: new Text(DateTime.now().toIso8601String()),
                  ));
                },
              ),
            ],
          ),
        ),
      );
    }
  }
  
  class RsetApi {
    static Future<List<EventSong>> getRawsAsync() {
      return compute(_getRaws, null);
    }
  
    static List<EventSong> _getRaws(pram1) {
      var rows = List<EventSong>();
      for (var i = 1; i < 12000; i++) {
        rows.add(EventSong(i));
        print("fetching raws " + (i / 12000).toString());
      }
      return rows;
    }
  }
  
  class Database {
    static Future saveRawsAsync(List<EventSong> rows) {
      return compute(_saveRaws, rows);
    }
  
    static _saveRaws(List<EventSong> rows) {
      for (var i = 1; i < rows.length; i++) {
        print("saving raws " + (i / rows.length).toString());
      }
    }
  }
  
  class EventSong {
    int id;
    EventSong(this.id);
  }
  

  Ref:

  • Parse JSON in the background - Flutter

  non-important Ref:

  • Flutter async : Beginner friendly guide for heavy lifting operations

  • Dart/Flutter : Converting timestamp - Stack Overflow

  • Display a snackbar - Flutter

  • sdk/file.dart at 1c4ad14fa3a0a1d5ecea10e3b04befecee3ffbcb · dart-lang/sdk

  • Search · openSync(){

  • sdk/file_impl.dart at 1c4ad14fa3a0a1d5ecea10e3b04befecee3ffbcb · dart-lang/sdk

  • Search · readAsLinesSync

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