Flutter 使用本地 sqlite 文件创建 ListView

Question

使用 sqflite 从本地 sql 文件 (chinook.db) 创建一个 ListView 初始问题已解决:I/flutter(5084):“ future ”的实例引用编码:https://github.com/tekartik/sqflite/blob/master/sqflite/doc/opening_asset_db.md感谢@aakash 的帮助

main.dart
body: Container(
        child: FutureBuilder(
          future: getSQL("albums"),
          builder: (BuildContext context, AsyncSnapshot snapshot) {
            print(snapshot.data);
            if (snapshot.data == null) {
              return Container(child: Center(child: Text("Loading...")));
            } else {
              return ListView.builder(
                itemCount: snapshot.data.length,
                itemBuilder: (BuildContext context, int index) {
                  return ListTile(
                    title: Text(snapshot.data[index].title),
                  );
                },
              );
            }
          },
        ),
      ),

getSQL.dart 
Future getSQL(String tableName) async {
  var databasesPath = await getDatabasesPath();
  var path = join(databasesPath, "chinook.db");
// Check if the database exists
  var exists = await databaseExists(path);
  if (!exists) {
    // Should happen only the first time you launch your application
    print("Creating new copy from asset");
    // Make sure the parent directory exists
    try {
      await Directory(dirname(path)).create(recursive: true);
    } catch (_) {}
    // Copy from asset
    ByteData data = await rootBundle.load(join("assets", "chinook.db"));
    List<int> bytes =
        data.buffer.asUint8List(data.offsetInBytes, data.lengthInBytes);
    // Write and flush the bytes written
    await File(path).writeAsBytes(bytes, flush: true);
  } else {
    print("Opening existing database");
  }
// open the database
  var db = await openDatabase(path, readOnly: true);

  List<Map> list = await db.rawQuery('SELECT * FROM $tableName');
  List theList = [];
  for (var n in list) {
    theList.add(MyCategoryFinal(n["Title"]));
  }
  return (theList);
}
class MyCategoryFinal {
  final String title;
  MyCategoryFinal(this.title);
}

Answer 1

我通过为 sqflite 表创建一个类解决了这个问题，在该 map 列表上运行一个循环并将这些 map 项转换为对象列表。

示例代码；

List<ItemBean> items = new List();
    list.forEach((result) {
      ItemBean story = ItemBean.fromJson(result);
      items.add(story);
    });

要创建对象，您可以使用 https://app.quicktype.io/ .这里可以传入json为其生成类。

之后你可以像这样使用 FutureBuilder 创建你的 ListView

       FutureBuilder(
          future: MyService.getAllItems(),
          builder: (context, snapshot) {
            if (!snapshot.hasData) {
              return Center(child: CircularProgressIndicator());
            }

            return ListView.builder(
              controller: listScrollController,
              itemCount: snapshot.data.length,
              reverse: true,
              itemBuilder: (context, index) {
                return Text(snapshot.data[index].itemName);
              },
            );
          },
        ),