輸入'列表<map<string, dynamic> &gt;' 不是 'Map 類型的子類型<dynamic, dynamic> ' </dynamic,></map<string,>

Question

我正在嘗試將 from List 設置為 Map 我收到此錯誤。

我從 Firestore 獲取數據，您可以在下面看到查詢和 output。

  List<Map<String, dynamic>> transactionData = [];
  List accountList = [];
  List availableAccount = [];

getData() async{
    final dataDB = await FirebaseFirestore.instance.collection('TransactionData').doc(getUid()).get();
    snapshot = dataDB;
    final Map<String, dynamic> documentData = snapshot.data() as Map<String, dynamic>;

    documentData.forEach((key, value) {
      availableAccount.add(key);
    });

    for(int j=0;j<availableAccount.length;j++){
      transactionData = (documentData[availableAccount[j]] as List).map((accountList) => accountList as Map<String, dynamic>).toList();
      accountList.add(transactionData);
    }
    _cards = accountList;
    print('Cards: $_cards');
    setState(() {
      _data = _cards![0];
    });
  }

Cards: [[{categoryName: Education, uid: LNM6JQuoKCPIANTyQHMKWLIzl5m1, amount: 3,000.00, lastUpdatedDate: 25-08-2022, createdDate: 25-08-2022, toAccountId: , type: Credit, transfer: N, accountId: 21Aug5298Sav, auto: Y, accountName: null, transactionId: deb1621, categoryLogo: assets/images/Education.png, untagged: N, categoryBackgroundColor: 0xffFFA2C0, currency: INR, transactionDate: 25-08-2022}, {categoryName: Education, uid: LNM6JQuoKCPIANTyQHMKWLIzl5m1, amount: 300.00, lastUpdatedDate: 25-08-2022, createdDate: 25-08-2022, toAccountId: , type: Debit, transfer: N, accountId: 21Aug5298Sav, auto: Y, accountName: null, transactionId: deb5366, categoryLogo: assets/images/Education.png, untagged: N, categoryBackgroundColor: 0xffFFA2C0, currency: INR, transactionDate: 25-08-2022}, {categoryName: Travelling, uid: LNM6JQuoKCPIANTyQHMKWLIzl5m1, amount: 100.00, lastUpdatedDate: 24-08-2022, createdDate: 24-08-2022, toAccountId: , type: , transfer: N, accountId: 21Aug5298Sav, auto: Y, accountName:<…>

有人可以幫我解決這個問題，當我將“_cards.[0]”設置為“_data”時出現錯誤。

Answer 1

您希望_cards是List<Map<String, dynamic>>但事實並非如此。 這是一個List<List<Map<String, dynamic>>>並嘗試將它的第一個項目List<Map<String, dynamic>>傳遞給Map<String, dynamic>的_data，這是一個問題。 如果你想將任何值從 _cards 傳遞給 _data 應該是這樣的：

_data = _cards![0][0];

如果要將List<List<Map<String, dynamic>>>轉換為List<Map<String, dynamic>> ，請執行以下操作：

List<String> newCards = [];
          
for (var item in _cards) {
  newCards = [...newCards, ...item];
}

接着：

_data = newCards[0];