问题描述

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

I am working on a Windows Phone 8.1 application involving location. I am receiving Json data from my API. My API returns data that looks like:

[{
    "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，它给了我一个错误:

I am deserializing my Json data and putting it into a class named LocationData. When I run my code, it gives me an error:

从 JsonReader 读取 JObject 时出错.当前 JsonReader 项不是对象:StartArray.路径

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:

Where am I going wrong? Here is my code:

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);
        }
    }

我也尝试使用 JArray.我的代码如下:

I also tried to use a JArray. My code is as below:

 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);
        }
    }

这也给了我一个错误:

无法将当前 JSON 数组(例如 [1,2,3])反序列化为 'MMI_SpeechRecog.Model.LocationData' 类型，因为该类型需要 JSON 对象(例如 {"name":"value"}) 正确反序列化.

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.

推荐答案

你的问题的第一部分是 为什么我会用这个代码得到一个 JsonReaderException?，但是这个(我的)答案中最相关的部分是:

The first part of your question is a duplicate of Why do I get a JsonReaderException with this code?, but the most relevant part from that (my) answer is this:

[A] JObject 不是 JSON.net 中所有内容的基本基本类型，但 JToken 是.所以即使你可以说，

[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];

在 C# 中，你不能说，

in C#, you can't say,

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

在 JSON.net 中.

in JSON.net.

您想要的是 JArray.Parse，它将接受您传递给它的数组(由 API 响应中的开头 [ 表示).这就是StartArray"的内容.在错误信息中告诉你.

What you want is JArray.Parse, which will accept the array you're passing it (denoted by the opening [ in your API response). This is what the "StartArray" in the error message is telling you.

至于你使用JArray时发生了什么，你使用的是arr而不是obj:

As for what happened when you used JArray, you're using arr instead of obj:

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

交换它，我相信它应该可以工作.

Swap that, and I believe it should work.

虽然我很想将 arr 直接反序列化为 IEnumerable<LocationData>，这样可以节省一些代码和遍历数组的工作量.如果不打算单独使用解析后的版本，最好避免使用.

Although I'd be tempted to deserialize arr directly as an IEnumerable<LocationData>, which would save some code and effort of looping through the array. If you aren't going to use the parsed version separately, it's best to avoid it.

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