string - 检索存储在 SQFlite 数据库(Flutter)中的数据？

Question

我有一个模型类 Pet二手 toMap和 fromMap :

  Map<String, dynamic> toMap() {
return {
  'id': id,
  'image': image,
  'name': name,
  'birth': birth,
  'colour': colour,
  'breed': breed,
  'hairlength': hairLength,
  'sterilized': sterilized,
  'vaccinated': vaccinated
   };
  }

    Pet.fromMap(Map<String, dynamic> map) {
    id = map['id'];
    image = map['image'];
    name = map['name'];
    birth = map['birth'];
    breed = map['breed'];
    colour = map['colour'];
    hairLength = map['hairlength'];
    sterilized = map['sterilized'];
    vaccinated = map['vaccinated'];
  }

我将所有内容都存储在我的数据库中并且我想检索图像(存储为字符串)所以我使用了这种方法:

  Future<List<String>> getImages() async {
    var dbClient = await db;
    List<Map> maps = await dbClient.rawQuery("SELECT * FROM $TABLE");
    List<String> images = [];
    if (maps.length > 0) {
       for (int i = 0; i < maps.length; i++) {
           images.add(Pet.fromMap(maps[i]).image);
      }
     }
    return images;
  }

如何使用 Future<List<String>>读取与每个图像关联的每个字符串？

Answer 1

问题有点模糊，假设像提到的评论一样，您想直接在小部件中使用该函数，您可以使用 FutureBuilder 或在完成后调用 initstate 和 setState 中的函数。

FutureBuilder 版本

class TextFutureWidget extends StatelessWidget {
  Future<List<String>> testFunction() async {
    return List<String>();
  }

  @override
  Widget build(BuildContext context) {
    final imagesFuture = testFunction();
    return Container(
        child: FutureBuilder(
      future: imagesFuture,
      builder: (context, snapshot) {
        if (!snapshot.hasData || snapshot.data == null) return Container();
        return Column(
          children: <Widget>[
            for (var item in snapshot.data) Text(item),
          ],
        );
      },
    ));
  }
}

初始状态版本

class TestWidget extends StatefulWidget {
  @override
  _TestWidgetState createState() => _TestWidgetState();
}

class _TestWidgetState extends State<TestWidget> {
  List<String> _images;
  List<String> get images => _images;
  set images(List<String> images) {
    if (mounted) setState(() => _images = images);
  }

  @override
  void initState() {
    super.initState();
    testFunction().then((value) => images = value);
  }

  Future<List<String>> testFunction() async {
    return List<String>();
  }

  @override
  Widget build(BuildContext context) {
    return Column(
      children: <Widget>[
        if(images != null)
          for (var item in images)
            Text(item),
      ],
    );
  }
}