Question

每次尝试重复该项目时，我都试图应用对话框警报，但是当我进行测试时，它最终给出了此错误，是否有人对如何解决此问题有任何提示？

 void SalvarMensagem() async {
    // select id_armarios from armarios where numero_serie = '$_numeroSerie'

    this._status = _status;
    _numeroSerie = _status.substring(48, 80);

    final QuerySnapshot result = await Future.value(Firestore.instance
        .collection("lockers")
        .where("numero_serie", isEqualTo: "$_numeroSerie")
        .limit(1)
        .getDocuments());

    final List<DocumentSnapshot> documents = result.documents;
    if (documents.length == 1) {
      duplicado(context);
    } else {
      await Firestore.instance
          .collection("lockers")
          .document()
          .setData({"numero_serie": _numeroSerie});
    }
  }

duplicado(BuildContext context){
  Alert(
    context: context,
    type: AlertType.error,
    title: "QR Code já cadastrado",
    buttons: [
      DialogButton(
        child: Text(
          "OK",
          style: TextStyle(color: Colors.white, fontSize: 20),
        ),
        onPressed: () => Navigator.pop(context),
        color: Colors.lightBlueAccent,
        width: 120,
      )
    ],
  ).show();
}

错误：

E / flutter（9129）：[错误：flutter / lib / ui / ui_dart_state.cc（148）] 未处理的异常：'package：flutter / src / widgets / localizations.dart'：断言失败：446行pos 12：'context！= null'：不正确。

Answer 1

duplicate(context, title, content) {
  showDialog(
    context: context,
    builder: (BuildContext context) {
      return AlertDialog(
        title: new Text(
          title,
        ),
        content: Padding(
          padding: const EdgeInsets.all(8.0),
          child: new Text(
            content,
          ),
        ),
        actions: <Widget>[
          new FlatButton(
            child: new Text(
              "OK",
              style: TextStyle(color: Colors.white),
            ),
            onPressed: () {
              Navigator.of(context).pop();
            },
            color: Colors.lightBlueAccent,
          ),
        ],
      );
    },
  );
}

更改警报功能并用duplicate(context,"QR Code já cadastrado","The content you wanted or delete it")调用它应该没问题。您可以使用功能参数更改标题和内容。

错误Dart / Flutter：“上下文！= null”：不正确

1 个答案: