如何在颤振中解析json

Question

我正在尝试获取来自 Http 库的 JSON 数据。我只想向用户显示第一个对象的“alert_description”值。我如何才能访问此属性？

我的 API 响应：

{
    "code": 0,
    "message": " success",
    "data": {
        "data": {
            "current_page": 1,
            "data": [
                {
                    "id": 62,
                    "user_id": 53,
                    "boxIdentifiant": 1924589682265245,
                    "boxName": "Box Sfax",
                    "alert_date": "2021-05-30",
                    "alert_time": "09:40",
                    "alert_description": "Panne Pression",
                    "alert_level": "warning"
                },
                {
                    "id": 61,
                    "user_id": 53,
                    "boxIdentifiant": 1924589682265243,
                    "boxName": "Box Tunis",
                    "alert_date": "2021-05-30",
                    "alert_time": "09:40",
                    "alert_description": "Panne Pression Roux",
                    "alert_level": "info"
                },
                {
                    "id": 58,
                    "user_id": 53,
                    "boxIdentifiant": 1924589682265244,
                    "boxName": "Box Office",
                    "alert_date": "2021-05-30",
                    "alert_time": "09:40",
                    "alert_description": "Panne Pression Roux",
                    "alert_level": "warning"
                },

我的代码：

 var response =
        await http.get(Uri.parse(ApiUtil.GET_ALERT), headers: headers);
    print("here================");
    // print(response);
    var data = json.decode(response.body);
    print(data['data']['data']['data']);
    if (data['status'] == 200) {
      showNotification(data['message'], flp);
    } else {
      print("no message");
    }

    return Future.value(true);
  });
}

Answer 1

用于解码这样的 JSON

{
"id":"xx888as88",
"timestamp":"2020-08-18 12:05:40",
"sensors":[
    {
     "name":"Gyroscope",
     "values":[
         {
          "type":"X",
          "value":-3.752716,
          "unit":"r/s"
         },
         {
           "type":"Y",
           "value":1.369709,
           "unit":"r/s"
         },
         {
           "type":"Z",
           "value":-13.085,
           "unit":"r/s"
         }
       ]
    }
  ]
}

你可以这样做：

void setReceivedText(String text) {
    Map<String, dynamic> jsonInput = jsonDecode(text);
    
    _receivedText = 'ID: ' + jsonInput['id'] + '\n';
    _receivedText += 'Date: ' +jsonInput['timestamp']+ '\n';
    _receivedText += 'Device: ' +jsonInput['sensors'][0]['name'] + '\n';
    _receivedText += 'Type: ' +jsonInput['sensors'][0]['values'][0]['type'] + '\n';
    _receivedText += 'Value: ' +jsonInput['sensors'][0]['values'][0]['value'].toString() + '\n';
    _receivedText += 'Type: ' +jsonInput['sensors'][0]['values'][1]['type'] + '\n';
    _receivedText += 'Value: ' +jsonInput['sensors'][0]['values'][1]['value'].toString() + '\n';
    _receivedText += 'Type: ' +jsonInput['sensors'][0]['values'][2]['type'] + '\n';
    _receivedText += 'Value: ' +jsonInput['sensors'][0]['values'][2]['value'].toString();
     _historyText = '\n' + _receivedText;
}

Answer 2

我不知道 Http 库是如何工作的，但是在 Dio 库中你不需要解码任何东西，它非常简单。看看这是否对您有帮助：

var response = await Dio().post(yourUrl, data: { param1: value1, param2: value2 });

for (var item in response.data['data']['data']['data'])
{
    print(item['alert_description']);
}

由于您使用的是GET方法，因此请分别使用Dio().get() 和queryParameters: 而不是Dio().post() 和data:。