使用 Firestore 进行 Flutter 搜索委托(delegate)

Question

我正在使用 Flutter Search Delegate 实现搜索功能，数据存储在 Firestore 中。我不明白为什么会出现这个错误。

Widget buildSuggestions(BuildContext context) {
  return StreamBuilder(
    stream: Firestore.instance.collection('todos').snapshots(),
    builder: (context, snapshot) {
      if (!snapshot.hasData) return new Text('Loading...');

      final results =
          snapshot.data.documents.where((a) => a['title'].contains(query));

      return ListView(
        children: results.map<Widget>((a) => Text(a['title'])).toList(),
      );
    },
  );
}

错误:

类型“(dynamic)=>dynamic”不是“test”类型“(DocumentSnapshot)=>bool”的子类型

Answer 1

更换线路

final results = snapshot.data.documents.where((a) => a['title'].contains(query));

到

final results = snapshot.data.documents.where((DocumentSnapshot a) => a.data['title'].contains(query));

还有这条线

children: results.map<Widget>((a) => Text(a['title'])).toList()

到

children: results.map<Widget>((a) => Text(a.data['title'])).toList()