反序列化Json Web API响应-嵌套对象
本文关键字：嵌套 对象 响应 API Json Web 反序列化 | 更新日期: 2023-09-27 18:17:18
我正在通过SSIS脚本组件获得Web API JSON响应，该响应以以下格式返回:
{
"Success": true,
"Response": {
"Applications": [
{
"App_ID": 1638486,
"App_Ref": "Test Example",
"Status": "Complete",
"Error_Code": null,
"Error_Message": null,
"Create_Dt": "2014-05-14 03:09:01.030 +00:00",
"Modify_Dt": "2014-05-14 03:10:59.757 +00:00",
"Client_Name": "Silver Chef",
"Client_Code": "SLVC01",
"Centrelink_Status": "Receiving_Logons"
},
{
"App_ID": 1637906,
"App_Ref": "SME Demo",
"Status": "Complete",
"Error_Code": null,
"Error_Message": null,
"Create_Dt": "2015-10-08 03:07:26.793 +00:00",
"Modify_Dt": "2015-10-08 03:23:32.833 +00:00",
"Client_Name": "Silver Chef",
"Client_Code": "SLVC01",
"Centrelink_Status": "Receiving_Logons"
},
{
"App_ID": 1585286,
"App_Ref": "Test",
"Status": "Receiving_Logons",
"Error_Code": null,
"Error_Message": null,
"Create_Dt": "2015-12-04 03:12:49.617 +00:00",
"Modify_Dt": "2015-12-04 03:12:49.617 +00:00",
"Client_Name": "Silver Chef",
"Client_Code": "SLVC01",
"Centrelink_Status": "Receiving_Logons"
}
],
"Current_Dt": "2016-11-11 01:01:01.743 +00:00",
"Last_App_Dt": "2016-10-03 22:48:56.397 +00:00",
"Count": 500,
"Total": 1870
}
}
public class Application
{
public int App_ID { get; set; }
public string App_Ref { get; set; }
public string Status { get; set; }
public int Error_Code { get; set; }
public string Error_Message { get; set; }
public DateTime Create_Dt { get; set; }
public DateTime Modify_Dt { get; set; }
public string Client_Name { get; set; }
public string Client_Code { get; set; }
public int Centrelink_Status { get; set; }
}
public class Response
{
public List<Application> Applications { get; set; }
public string Current_Dt { get; set; }
public string Last_App_Dt { get; set; }
public int Count { get; set; }
public int Total { get; set; }
}
public class RootObject
{
public bool Success { get; set; }
public Response Response { get; set; }
}
And this is the method that I am using to get the response.
private RootObject GetWebServiceResult(string vAPIUrl)
{
string vAPIToken = Variables.APIToken;
//Create Web Request
HttpWebRequest apireq = (HttpWebRequest)WebRequest.Create(vAPIUrl);
apireq.ContentType = "application/json";
apireq.Method = "POST";
string jsonPostStr = "{'"Settings'": {'"API_Token'": '"" + vAPIToken + "'"}, '"Payload'": {}}";
byte[] postString = Encoding.UTF8.GetBytes(jsonPostStr);
apireq.ContentLength = postString.Length;
Stream jsonStream = apireq.GetRequestStream();
jsonStream.Write(postString, 0, postString.Length);
jsonStream.Close();
// Get Web Response
HttpWebResponse apirsp = (HttpWebResponse)apireq.GetResponse();
RootObject jsonResponse = null;
Stream jsonRspStream = apirsp.GetResponseStream();
string apiResponseString = null;
using (StreamReader reader = new StreamReader(jsonRspStream))
{
apiResponseString = reader.ReadToEnd();
Console.WriteLine(apiResponseString);
reader.Close();
}
JavaScriptSerializer returnJson = new JavaScriptSerializer();
//var serialJsonStr = returnJson.Serialize(apiResponseString);
System.Windows.Forms.MessageBox.Show(apiResponseString);
jsonResponse = returnJson.Deserialize<RootObject>(apiResponseString);
return jsonResponse;
}
我的问题是returnJson.Deserialize(apiResponseString);似乎返回null，随后使此失败。
我错过了什么?我想我在这个阶段有点代码盲。
Thanks in advance
Application类有几个问题:
-
您已将
Application.Error_Code定义为整数:public int Error_Code { get; set; }但实际上，在JSON中，它有一个空值:
"Error_Code": null,因此，
Error_Code需要是引用类型(string)或可空值类型(int?)，这取决于它在非空时所持有的内容。 -
你已经定义了
Centrelink_Status作为int，但在JSON中它是一个字符串:"Centrelink_Status": "Receiving_Logons"因此在数据模型中也需要是字符串
因此你的Application类应该看起来像:
public class Application
{
public int App_ID { get; set; }
public string App_Ref { get; set; }
public string Status { get; set; }
public int? Error_Code { get; set; } // Or string, if not numeric
public string Error_Message { get; set; }
public DateTime Create_Dt { get; set; }
public DateTime Modify_Dt { get; set; }
public string Client_Name { get; set; }
public string Client_Code { get; set; }
public string Centrelink_Status { get; set; }
}
如果JSON中有null值的机会，您可能还希望将这些DateTime属性设置为可空。
顺便说一下，当我试图反序列化这个JSON时，我得到了一个异常，而不是一个空值返回:
System.InvalidOperationException was unhandled
Message="Cannot convert null to a value type."
Source="System.Web.Extensions"
StackTrace:
在实际的代码中，您是否捕获并吞下异常?这是一个坏主意，因为它往往会隐藏诸如此类的错误。至少，在调试时，只要抛出任何异常(包括第一次异常)，您就应该中断异常——即使这是而不是的默认行为。请参阅使用调试器管理异常。如果您发现某些类型的异常经常被抛出，并且与调试无关，您可以选择性地重新忽略它们。如果你这样做了，这个bug就会更容易追踪。诚然，这个错误不能很好地解释，但它确实给了一个提示。如果使用json.net对JSON进行反序列化，则错误消息将更加清晰:
Newtonsoft.Json.JsonSerializationException occurred
Message="Error converting value {null} to type 'System.Int32'. Path 'Response.Applications[0].Error_Code', line 9, position 26."
Source="Newtonsoft.Json"
StackTrace:
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.EnsureType(JsonReader reader, Object value, CultureInfo culture, JsonContract contract, Type targetType) in C:'Development'Releases'Json'Working'Newtonsoft.Json'Working-Signed'Src'Newtonsoft.Json'Serialization'JsonSerializerInternalReader.cs:line 986
InnerException: System.InvalidCastException
Message="Null object cannot be converted to a value type."
Source="mscorlib"
StackTrace:
at System.Convert.ChangeType(Object value, Type conversionType, IFormatProvider provider)
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.EnsureType(JsonReader reader, Object value, CultureInfo culture, JsonContract contract, Type targetType) in C:'Development'Releases'Json'Working'Newtonsoft.Json'Working-Signed'Src'Newtonsoft.Json'Serialization'JsonSerializerInternalReader.cs:line 979
InnerException: