在 Newtonsoft.Json.Linq 中使用 Jobject 解析多个对象

Question

我正在尝试将 google 语音的结果解析为文本 API。 json 响应是：

{"result":[]}
{"result":[
          {"alternative":[
                         {"transcript":"hello Google how are you     feeling","confidence":0.96274596},
                         {"transcript":"hello Google how are you today","confidence":0.97388196},
                         {"transcript":"hello Google how are you picking","confidence":0.97388196},
                         {"transcript":"hello Google how are you kidding","confidence":0.97388196}
                         ]
         ,"final":true}]
,"result_index":0
}

现在我试图通过 JObject 解析它。问题发生在解析出现两次的 Result 对象时，我该如何解析第二个 Result 对象。这是我正在尝试的代码：

              StreamReader SR_Response = new StreamReader(HWR_Response.GetResponseStream());
              Console.WriteLine(SR_Response.ReadToEnd()+SR_Response.ToString());
              String json_response = SR_Response.ReadToEnd() + SR_Response.ToString();
              JObject joo = JObject.Parse(json_response);
              JArray ja = (JArray)joo["result"];

                        foreach (JObject o in ja)
                        {
                            JArray ja2 = (JArray)o["alternative"];
                            foreach (JObject h in ja2)
                            {
                                Console.WriteLine(h["transcript"]);
                            }
                        }

我尝试使用反序列化目标代码的下一个解决方案是：

                string responseFromServer = (SR_Response.ReadToEnd());
                String[] jsons = responseFromServer.Split('\n');
                String text = "";
                foreach (String j in jsons)
                {
                    dynamic jsonObject = JsonConvert.DeserializeObject(j);
                    if (jsonObject == null || jsonObject.result.Count <= 0)
                    {
                        continue;
                    }
                    Console.WriteLine((string)jsonObject["result"]["alternative"][0]["transcript"]);
                    text = jsonObject.result[0].alternative[0].transcript;
                }
                Console.WriteLine("MESSAGE : "+text);

Answer 1

您拥有的是一系列 JSON 根对象，它们连接在一起成为一个流。如 Read Multiple Fragments With JsonReader such a stream can be deserialized by setting JsonReader.SupportMultipleContent = true 中所述。因此，要反序列化您的流，您应该首先引入以下扩展方法：

public static class JsonExtensions
{
    public static IEnumerable<T> DeserializeObjects<T>(Stream stream, JsonSerializerSettings settings = null)
    {
        var reader = new StreamReader(stream); // Caller should dispose
        return DeserializeObjects<T>(reader, settings);
    }

    public static IEnumerable<T> DeserializeObjects<T>(TextReader textReader, JsonSerializerSettings settings = null)
    {
        var ser = JsonSerializer.CreateDefault(settings);
        var reader = new JsonTextReader(textReader); // Caller should dispose

        reader.SupportMultipleContent = true;

        while (reader.Read())
        {
            if (reader.TokenType == JsonToken.None || reader.TokenType == JsonToken.Undefined || reader.TokenType == JsonToken.Comment)
                continue;
            yield return ser.Deserialize<T>(reader);
        }
    }
}

接下来，使用 code-generation 实用程序，例如 http://json2csharp.com/，为单个 JSON 根对象生成 c# 类，如下所示：

public class Alternative
{
    public string transcript { get; set; }
    public double confidence { get; set; }
}

public class Result
{
    public List<Alternative> alternative { get; set; }
    public bool final { get; set; }
}

public class RootObject
{
    public List<Result> result { get; set; }
    public int result_index { get; set; }
}

并反序列化如下：

List<RootObject> results;
using (var stream = HWR_Response.GetResonseStream())
{
    results = JsonExtensions.DeserializeObjects<RootObject>(stream).ToList();
}

完成此操作后，您可以使用标准的 c# 编程技术，例如 Linq 来枚举 transcript 值，例如：

var transcripts = results
    .SelectMany(r => r.result)
    .SelectMany(r => r.alternative)
    .Select(a => a.transcript)
    .ToList();

如果您不想为 JSON 集合定义固定数据模型，您可以直接反序列化为 JObject 的列表，如下所示：

List<JObject> objs;
using (var stream = HWR_Response.GetResonseStream())
{
    objs = JsonExtensions.DeserializeObjects<JObject>(stream).ToList();
}

然后您可以使用 SelectTokens() 来 select 每个对象内嵌套的所有 "transcript" 属性的值：

var transcripts = objs
    // The following uses the JSONPath recursive descent operator ".." to pick out all properties named "transcript".
    .SelectMany(o => o.SelectTokens("..transcript")) 
    .Select(t => t.ToString())
    .ToList();

更新的示例 fiddle 显示了两个选项。

在 Newtonsoft.Json.Linq 中使用 Jobject 解析多个对象

Parsing multiple objects using Jobject in Newtonsoft.Json.Linq

c#

linq

json

json.net

google-speech-api