c# - 从 JsonReader 读取 JObject 时出错。当前 JsonReader 项不是对象 : StartArray. 路径

Question

我正在开发一个涉及位置的 Windows Phone 8.1 应用程序。我正在从我的 API 接收 Json 数据。我的 API 返回的数据如下所示:

[{
    "country": "India",
    "city": "Mall Road, Gurgaon",
    "area": "Haryana",
    "PLZ": "122002",
    "street": "",
    "house_no": "",
    "POI": "",
    "type": "17",
    "phone": "",
    "lng": 77.08972334861755,
    "lat": 28.47930118040612,
    "formatted_address": "Mall Road, Gurgaon 122002, Haryana, India"
},
{
    "country": "India",
    "city": "Mall Road, Kanpur",
    "area": "Uttar Pradesh",
    "PLZ": "208004",
    "street": "",
    "house_no": "",
    "POI": "",
    "type": "17",
    "phone": "",
    "lng": 80.35783410072327,
    "lat": 26.46026740300029,
    "formatted_address": "Mall Road, Kanpur 208004, Uttar Pradesh, India"
},
{
    "country": "India",
    "city": "Mall Road Area, Amritsar",
    "area": "Punjab",
    "PLZ": "143001",
    "street": "",
    "house_no": "",
    "POI": "",
    "type": "17",
    "phone": "",
    "lng": 74.87286686897278,
    "lat": 31.64115178002094,
    "formatted_address": "Mall Road Area, Amritsar 143001, Punjab, India"
},
{
    "country": "India",
    "city": "Vasant Kunj (Mall Road Kishan Garh), New Delhi",
    "area": "Delhi",
    "PLZ": "110070",
    "street": "",
    "house_no": "",
    "POI": "",
    "type": "18",
    "phone": "",
    "lng": 77.1434211730957,
    "lat": 28.51363217008815,
    "formatted_address": "Vasant Kunj (Mall Road Kishan Garh), New Delhi 110070, Delhi, India"
}]

我正在反序列化我的 Json 数据并将其放入名为 LocationData 的类中。当我运行我的代码时，它给我一个错误:

Error reading JObject from JsonReader. Current JsonReader item is not an object: StartArray. Path

我哪里错了？这是我的代码:

private async void GetAPIData()
    {
        string _serviceUrl = "https://api.myweblinkapiprovider/v2&q=" + UserRequestedLocation;
        HttpClient client = new HttpClient();

        HttpResponseMessage responce = await client.GetAsync(new Uri(_serviceUrl));

        if (responce.Content != null)
        {
            var respArray = JObject.Parse(await responce.Content.ReadAsStringAsync());
            JsonSerializerSettings settings = new JsonSerializerSettings();
            settings.NullValueHandling = NullValueHandling.Ignore;
            settings.MissingMemberHandling = MissingMemberHandling.Ignore;
            var rcvdData = JsonConvert.DeserializeObject<LocationData>(respArray.ToString(), settings);
            UpdateMapData(rcvdData);
            UpdateTextData(rcvdData);
        }
    }

我还尝试使用 JArray。我的代码如下:

 private async void GetAPIData()
    {
        string _serviceUrl = "https://api.myweblinkprovider.com/v3?fun=geocode&lic_key=MyKey" + UserRequestedLocation;
        HttpClient client = new HttpClient();

        HttpResponseMessage responce = await client.GetAsync(new Uri(_serviceUrl));

        JArray arr = JArray.Parse(await responce.Content.ReadAsStringAsync());

        foreach (JObject obj in arr.Children<JObject>())
        {
            JsonSerializerSettings settings = new JsonSerializerSettings();
            settings.NullValueHandling = NullValueHandling.Ignore;
            settings.MissingMemberHandling = MissingMemberHandling.Ignore;
            var rcvdData = JsonConvert.DeserializeObject<LocationData>(arr.ToString(), settings);
            UpdateMapData(rcvdData);
            UpdateTextData(rcvdData);
        }
    }

它也给我一个错误:

Cannot deserialize the current JSON array (e.g. [1,2,3]) into type 'MMI_SpeechRecog.Model.LocationData' because the type requires a JSON object (e.g. {"name":"value"}) to deserialize correctly.

Answer 1

您问题的第一部分与 Why do I get a JsonReaderException with this code? 重复，但与(我的)答案最相关的部分是:

[A] JObject isn't the elementary base type of everything in JSON.net, but JToken is. So even though you could say,

object i = new int[0];

in C#, you can't say,

JObject i = JObject.Parse("[0, 0, 0]");

in JSON.net.

你要的是JArray.Parse ，它将接受您传递给它的数组(在您的 API 响应中用开头 [ 表示)。这就是错误消息中的“StartArray”告诉您的内容。

至于你使用JArray时发生了什么, 你正在使用 arr而不是 obj :

var rcvdData = JsonConvert.DeserializeObject<LocationData>(arr /* <-- Here */.ToString(), settings);

交换它，我相信它应该可以工作。

尽管我很想反序列化 arr直接作为 IEnumerable<LocationData> ，这将节省一些代码和遍历数组的工作量。如果您不打算单独使用解析后的版本，最好避免使用它。