为API调用Xml2Json建立Json模型

Question

我正在调用一个在XMl中返回数据的Api

然后，我使用XML将其从Json转换为Xml2Json，然后解码并获取一个JsonMap，这将很好地返回一个映射。

然后，当我去做locations.fromJson，以便能够从我的模型中调用数据时，它是作为null返回的。

我想从XML转换可能会很复杂，但我已经尝试了所有的可能性，解析了整个响应，分析了我需要的部分，并以所有可能的方式修改了模型。

数据以Json的形式返回很好，但是当使用通过quicktype.io生成的模型解析它时，只会有一些断开。

当我以任何方式调用它时，无论是print还是数据检索，它都会在null上返回vehicleActivity

打电话

Future<Locations> fetchLiveLocations() async {
    var client = http.Client();
    var locations;
    Xml2Json xml2Json = new Xml2Json(); 

    
 try{
    var response = await client.get(
    'https_call');    
    if (response.statusCode == 200) {
    xml2Json.parse(response.body);
    var jsonString = xml2Json.toGData();
    var jsonMap = json.decode(jsonString);
    //jsonMap is returning fine

    locations = Locations.fromJson(jsonMap);
    //Returning as null

  }
 } catch(Exception) {
  return locations;
 }

  return locations;
 }   

Json模型的上部

import 'dart:convert';

Locations locationsFromJson(String str) => Locations.fromJson(json.decode(str));

String locationsToJson(Locations data) => json.encode(data.toJson());

class Locations {
    Locations({
        this.vehicleActivity,
    });

    List<VehicleActivity> vehicleActivity;

    factory Locations.fromJson(Map<String, dynamic> json) => Locations(
        vehicleActivity: List<VehicleActivity>.from(json["VehicleActivity"].map((x) => VehicleActivity.fromJson(x))),
    );

    Map<String, dynamic> toJson() => {
        "VehicleActivity": List<dynamic>.from(vehicleActivity.map((x) => x.toJson())),
    };
}

class VehicleActivity {
    VehicleActivity({
        this.recordedAtTime,
        this.itemIdentifier,
        this.validUntilTime,
        this.monitoredVehicleJourney,
        this.extensions,
    });

    DateTime recordedAtTime;
    String itemIdentifier;
    DateTime validUntilTime;
    MonitoredVehicleJourney monitoredVehicleJourney;
    Extensions extensions;

    factory VehicleActivity.fromJson(Map<String, dynamic> json) => VehicleActivity(
        recordedAtTime: DateTime.parse(json["RecordedAtTime"]),
        itemIdentifier: json["ItemIdentifier"],
        validUntilTime: DateTime.parse(json["ValidUntilTime"]),
        monitoredVehicleJourney: MonitoredVehicleJourney.fromJson(json["MonitoredVehicleJourney"]),
        extensions: Extensions.fromJson(json["Extensions"]),
    );

返回的XML文件

<Siri xmlns="http://www.siri.org.uk/siri" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.siri.org.uk/siri http://www.siri.org.uk/schema/2.0/xsd/siri.xsd" version="2.0">
<ServiceDelivery>
<ResponseTimestamp>2021-12-03T18:11:05.408806+00:00</ResponseTimestamp>
<ProducerRef>ItoWorld</ProducerRef>
<VehicleMonitoringDelivery>
<ResponseTimestamp>2021-12-03T18:11:05.408806+00:00</ResponseTimestamp>
<RequestMessageRef>5747b24f</RequestMessageRef>
<ValidUntil>2021-12-03T18:16:05.408806+00:00</ValidUntil>
<ShortestPossibleCycle>PT5S</ShortestPossibleCycle>

<VehicleActivity>
<RecordedAtTime>2021-12-03T18:10:01+00:00</RecordedAtTime>
<ItemIdentifier>ad2c7031-ceac-4e7c-bc0c-9e667ad00dfe</ItemIdentifier>
<ValidUntilTime>2021-12-03T18:16:05.408968</ValidUntilTime>
<MonitoredVehicleJourney>
<LineRef>4</LineRef>
<DirectionRef>inbound</DirectionRef>
<FramedVehicleJourneyRef>
<DataFrameRef>2021-12-03</DataFrameRef>
<DatedVehicleJourneyRef>4_20211203_18_04</DatedVehicleJourneyRef>
</FramedVehicleJourneyRef>
<PublishedLineName>4</PublishedLineName>
<OperatorRef>FTVA</OperatorRef>
<DestinationRef>03700324</DestinationRef>
<VehicleLocation>
<Longitude>-0.719601</Longitude>
<Latitude>51.520305</Latitude>
</VehicleLocation>
<Bearing>30.0</Bearing>
<BlockRef>801312</BlockRef>
<VehicleRef>69921</VehicleRef>
</MonitoredVehicleJourney>
<Extensions>
<VehicleJourney>
<Operational>
<TicketMachine>
<TicketMachineServiceCode>B4</TicketMachineServiceCode>
<JourneyCode>1815</JourneyCode>
</TicketMachine>
</Operational>
<VehicleUniqueId>69921</VehicleUniqueId>
<DriverRef>801312</DriverRef>
</VehicleJourney>
</Extensions>
</VehicleActivity>

Answer 1

下面是一个示例VehicleActivity类--注意它不处理任何错误，比如缺少XML标记或不可解析的日期，您应该自己添加这些错误。

class VehicleActivity {
  VehicleActivity({
    this.recordedAtTime,
    this.itemIdentifier,
    this.validUntilTime,
  });

  DateTime? recordedAtTime;
  String? itemIdentifier;
  DateTime? validUntilTime;

  factory VehicleActivity.fromElement(XmlElement vaElement) => VehicleActivity(
        recordedAtTime: DateTime.parse(
          vaElement.findElements('RecordedAtTime').first.text,
        ),
        itemIdentifier: vaElement.findElements('ItemIdentifier').first.text,
        validUntilTime: DateTime.parse(
          vaElement.findElements('ValidUntilTime').first.text,
        ),
      );
}

对于它找到的每个vehicle活动标记，您可以使用封装标记中的工厂方法(类似于JSON解析器的编写方式)。(请注意，XML可以有多个同名标记，这就是为什么代码使用first查找(希望)一个也是唯一的标记的原因。如果您想正确地解析XML，就需要处理这个问题--并且注意，通过JSON的过程可能会打破这个问题--但是不能用简单的模式。)

下面是一个简单的示例，它只找到所有的车辆活动标记：

  final doc = XmlDocument.parse(utf8.decode(response.bodyBytes));
  final allActivities = doc
      .findAllElements('VehicleActivity')
      .map((e) => VehicleActivity.fromElement(e))
      .toList();
  print(allActivities);