颤振错误-“参数不匹配的闭包调用：函数'[]'接收器：闭包：（）=> Map<String，dynamic>来自函数'data'：”

Question

我在 Flutter 应用上显示来自 Firestore 的数据时遇到了这个问题

错误：

Closure call with mismatched arguments: function '[]'
Receiver: Closure: () => Map<String, dynamic> from Function 'data':.
Tried calling: []("quizImgUrl")
Found: []() => Map<String, dynamic>

我的代码：

  Widget QuizList() {
    return Container(
      child: StreamBuilder(
        stream: quizStream,
        builder: (context, snapshot) {
          return snapshot.data == null
              ? Container()
              : ListView.builder(
                  itemCount: snapshot.data.documents.length,
                  itemBuilder: (context, index) {
                    snapshot.data.documents
                        .map((doc) => new ListTile(
                            title: new Text(doc["quizTitle"]),
                            subtitle: new Text(doc["quizImgUrl"].toString())))
                        .toList();
                    return QuizTile(
                      imgUrl: snapshot.data.documents[index].data['quizImgUrl'],
                      desc: snapshot
                          .data.documents[index].data['quizDescription'],
                      title: snapshot.data.documents[index].data['quizTitle'],
                    );
                  });
        },
      ),
    );
  }

数据库代码：

  Future<void> addQuestionData(Map questionData, String quizId) async {
    await FirebaseFirestore.instance
        .collection("Quiz")
        .doc(quizId)
        .collection("QNA")
        .add(questionData)
        .catchError((e) {
      print(e);
    });
  }

Full code

Answer 1

好的，你需要先调用 data() 方法。然后你可以得到索引项的值。应该是这样的：

      return QuizTile(
                  imgUrl: snapshot.data.documents[index].data()["quizImgUrl"],
                  desc: snapshot
                      .data.documents[index].data()["quizDescription"],
                  title: snapshot.data.documents[index].data()["quizTitle"],
                );