flutter - 我刚刚开始使用颤振，如果有人可以在应用程序的此页面中帮助我进行分页，那就太好了

Question

我有一个 'brews' 的 firestore 收藏。无法找到对 Brews 列表进行分页的方法。如果需要，您可以在 ( https://github.com/iamshaunjp/flutter-firebase/tree/lesson-27 )找到整个代码。谢谢..

class BrewList extends StatefulWidget {
  @override
  _BrewListState createState() => _BrewListState();
}

class _BrewListState extends State<BrewList> {
  @override
  Widget build(BuildContext context) {

    final brews = Provider.of<List<Brew>>(context) ?? [];

    return ListView.builder(
      itemCount: brews.length,
      itemBuilder: (context, index) {
        return BrewTile(brew: brews[index]);
      },
    );
  }
}

标签： flutter

Answer 1

好的，很抱歉延迟回答，但这就是我认为你的功能看起来像这样将你所有的 brews 保存到一个列表中作为 brews 然后你可以将它们映射到小部件。

Future<void> queryFirebase(String starting, String ending) async {
    final List<Brew> brewsList = [];  //this need to be intialized higher up not in this function
    //if you intialized it in this function it will reset to empty every time you call the function

    QuerySnapshot brewsSnapshot = await Firestore.instance
        .collection('collection')
        .where('name', isGreaterThanOrEqualTo: starting)
        .where('name', isLessThanOrEqualTo: ending)
        .orderBy('name')//this sorts your query if you want that
        .getDocuments();

    if (brewsSnapshot == null) {
      return;
    }

    brewsSnapshot.documents.forEach(
      (DocumentSnapshot brewsDocuments) => {
        brewsList.add(
          Brew(
            sugars: brewsDocuments.data['sugars'],
            name: brewsDocuments.data['name'],
            strength: int.parse(
              brewsDocuments.data['sugars'],
            ),
          ),
        ),
      },
    );
    notifyListeners();
  }

那么对该函数的调用将类似于

await queryFirebase('A', //name of last brew you want displayed initially)
await queryFirebase('//next brew after last one from last function', //name of last brew you want displayed )
await queryFirebase('//next brew after last one from last function', 'Z' )