Json.NET获取嵌套的jToken值

问题描述：

我正在使用Json.NET解析json http响应，并且具有正常工作的代码，但是可以肯定的是，我将以一种过于复杂的方式进行处理.我的问题是，是否有更直接的方法可以通过路径获取子jToken和/或反序列化它，而无需遍历每个级别.

I am working at parsing a json http response with Json.NET and have working code, but am pretty sure I am going about it in an overly complicated way. My question is if there is a more direct way to get a child jToken by path and/or de-serialize it without foreaching every level.

我尝试了这种方法，但是它返回null:

I tried this approach but it returns null:

  JObject jObj = JObject.Parse( text );
  JToken myVal;
  jObj.TryGetValue( "response.docs", out myVal );

这是我工作过于复杂的代码，包括反序列化:

Here is my working overly complicated code, including de-serialization:

  JObject jObj = JObject.Parse( text );

  foreach( var kv in jObj ) {
    if( kv.Key == "response" ) {
      foreach( JToken jt in kv.Value ) {
        if( jt.Path == "response.docs" ) {
          JEnumerable<JToken> children = jt.Children();
          foreach( JToken t in children ) {       
            //THIS WORKS BUT IS NOT ELEGANT 
            Solr_User[] su = t.ToObject<Solr_User[]>();
          }
        }
      }
    }
  }

这是JSON原始响应，仅供参考:

And here is the JSON raw response just for reference:

{
  "responseHeader":{
    "status":0,
    "QTime":0,
    "params":{
      "q":"*:*",
      "indent":"on",
      "wt":"json"}},
  "response":{"numFound":4,"start":0,"docs":[
      {
        "id":3,
        "first_name":"Bob",
        "_version_":"1558902640594649088"},
      {
        "id":4,
        "first_name":"Sam",
        "_version_":"1558902640613523456"},
      {
        "id":2,
        "first_name":"Fred",
        "_version_":"1558902640613523457"},
      {
        "id":1,
        "first_name":"Max",
        "_version_":"1558902640613523458"}]
  }}

答

您可以使用

You can use SelectToken() to select a token from deep within the LINQ-to-JSON hierarchy for deserialization. In two lines:

var token = jObj.SelectToken("response.docs");
var su = token == null ? null : token.ToObject<Solr_User []>();

或者在一行中，当缺少所选令牌时，有条件地反序列化空JToken :

Or in one line, by conditionally deserializing a null JToken when the selected token is missing:

var su = (jObj.SelectToken("response.docs") ?? JValue.CreateNull()).ToObject<Solr_User []>();

样本小提琴.

在c#6或更高版本中，使用

In c# 6 or later it's even easier to deserialize a nested token in one line using the null conditional operator:

var su = jObj.SelectToken("response.docs")?.ToObject<Solr_User []>();

甚至

var su = jObj?["response"]?["docs"]?.ToObject<Solr_User []>();

请注意，SelectTokens()比 JToken索引稍微宽容，因为SelectTokens()对于错误类型的查询(例如，如果"response"的值是字符串文字而不是嵌套对象)将返回null，而索引运算符将引发异常.

Note that SelectTokens() is slightly more forgiving than the JToken index operator, as SelectTokens() will return null for a query of the wrong type (e.g. if the value of "response" were a string literal not a nested object) while the index operator will throw an exception.

Json.NET获取嵌套的jToken值

相关推荐