Unable to parse JSON from Telnyx Api - asp.net-core

Question

I am developing an endpoint in C# to accept JSON posted from an external provider (Telnyx). Here is a sample of the data:
{
"data": {
"event_type": "fax.received",
"id": "e15c28d4-147e-420b-a638-2a2647315577",
"occurred_at": "2021-11-19T16:37:02.863682Z",
"payload": {
"call_duration_secs": 35,
"connection_id": "1771912871052051547",
"direction": "inbound",
"fax_id": "2a168c93-3db5-424b-a408-b70a3da625bc",
"from": "[phone]",
"media_url": "https://s3.amazonaws.com/faxes-prod/999",
"page_count": 1,
"partial_content": false,
"status": "received",
"to": "[phone]",
"user_id": "dc6e79fa-fe3b-462b-b3a7-5fb7b3111b8a"
},
"record_type": "event"
},
"meta": {
"attempt": 1,
"delivered_to": "https://webhook.site/27ef892c-c371-4976-ae22-22deea57080e"
}
}
I have verified this is valid JSON through https://jsonlint.com/. I created a model:
public class myDeserializedClass
{
public class Payload
{
public int call_duration_secs { get; set; }
public string connection_id { get; set; }
public string direction { get; set; }
public string fax_id { get; set; }
public string from { get; set; }
public string media_url { get; set; }
public int page_count { get; set; }
public bool? partial_content { get; set; }
public string status { get; set; }
public string to { get; set; }
public string user_id { get; set; }
}
public class Data
{
public string event_type { get; set; }
public string id { get; set; }
public DateTime occurred_at { get; set; }
public Payload payload { get; set; }
public string record_type { get; set; }
}
public class Meta
{
public int attempt { get; set; }
public string delivered_to { get; set; }
}
public class Root
{
public Data data { get; set; }
public Meta meta { get; set; }
}
}
The controller being posted to looks like:
[HttpPost]
public IActionResult InboundFax(myDeserializedClass json)
{
try
{
Root myDeserializedClass = JsonConvert.DeserializeObject<Root>(json.ToString().Trim());
return Content("OK");
}
catch(Exception ex)
{
return Content(ex.ToString());
}
}
I am receiving the error: Newtonsoft.Json.JsonReaderException: Unexpected character encountered while parsing value: K. Path '', line 0, position 0. each time the API tries to post to my endpoint. I have also tried posting data using Postman and receive the same error message. Additionally, there are examples of JSON posting on the API website at https://developers.telnyx.com/docs/v2/programmable-fax/tutorials/receive-a-fax-via-api. Since my application fails with both postman and real-time API calls, I'm am working on the assumption the problem is my code, but can't be 100% certain and don't know how to fix it. This is a mission critical problem that I need to solve. Any help would be appreciated.

Answer 1

First of all, the class is bad. Should be:
public class Payload
{
public int call_duration_secs { get; set; }
public string connection_id { get; set; }
public string direction { get; set; }
public string fax_id { get; set; }
public string from { get; set; }
public string media_url { get; set; }
public int page_count { get; set; }
public bool? partial_content { get; set; }
public string status { get; set; }
public string to { get; set; }
public string user_id { get; set; }
}
public class Data
{
public string event_type { get; set; }
public string id { get; set; }
public DateTime occurred_at { get; set; }
public Payload payload { get; set; }
public string record_type { get; set; }
}
public class Meta
{
public int attempt { get; set; }
public string delivered_to { get; set; }
}
public class myDeserializedClass
{
public Data data { get; set; }
public Meta meta { get; set; }
}
It depends on the data that you are getting, but if you are getting the object, you don't need to convert it to work:
[HttpPost]
public IActionResult InboundFax(myDeserializedClass json)
{
try
{
//Work directly with json as object, forget "root" is: myDeserializedClass
return Content("OK");
}
catch(Exception ex)
{
return Content(ex.ToString());
}
}
or if you are getting the json as string:
[HttpPost]
public IActionResult InboundFax(string json)
{
try
{
//Work directly with json as object
myDeserializedClass myInstance= JsonConvert.DeserializeObject<myDeserializedClass>(json);
return Content("OK");
}
catch(Exception ex)
{
return Content(ex.ToString());
}
}
UPDATE AFTER TESTING IT:
I test it with a dummy controller:
[HttpPost]
public ActionResult InboundFax(myDeserializedClass json)
{
try
{
//Just dummy test
if (json.meta.attempt == 1)
{
return Content("OK");
}
else {
return Content("NO");
}
//Work directly with json as object, forget "root" is: myDeserializedClass
}
catch (Exception ex)
{
return Content(ex.ToString());
}
}
in a HomeController (blank template from MVC Web just dummy)
So posting to:
https://localhost:44334/Home/InboundFax
METHOD: POST
With the following data:
{
"data": {
"event_type": "fax.received",
"id": "e15c28d4-147e-420b-a638-2a2647315577",
"occurred_at": "2021-11-19T16:37:02.863682Z",
"payload": {
"call_duration_secs": 35,
"connection_id": "1771912871052051547",
"direction": "inbound",
"fax_id": "2a168c93-3db5-424b-a408-b70a3da625bc",
"from": "[phone]",
"media_url": "https://s3.amazonaws.com/faxes-prod/999",
"page_count": 1,
"partial_content": false,
"status": "received",
"to": "[phone]",
"user_id": "dc6e79fa-fe3b-462b-b3a7-5fb7b3111b8a"
},
"record_type": "event"
},
"meta": {
"attempt": 1,
"delivered_to": "https://webhook.site/27ef892c-c371-4976-ae22-22deea57080e"
}
}
Little quickwatch you see it map everything:
Could mean the POSTMAN is wrong configurated?
I use the following header:
Content-Type: application/json
I'm using TALEND API TESTER for Chrome, but every REST client is similar
With POSTMAN, same result, OK. Check for body: raw, type JSON, and header with the content type applicantion/json

Answer 2

Well, I am not sure if I have an answer or not, however, I did manage to get the application working by changing the endpoint to a WebApi instead of a MVC controller. I was under the impression a MVC controller could accept json data, however, I was unable to ever get it working. Once I changed it, everyting worked perfectly.