Jtoken as Post Parameter in aspnet Core 3.1

Question

User718448626 posted

I have an application that was written in aspnet core 2.1 and I did an upgrade to core 3.1 the web API failed.  Why is JToken now not valid parameter?  

// This works on core 2.1 but failed on 3.1

[HttpPost]
public async Task<IActionResult> PostAsync([FromBody] JToken value)
{  

// code here

  return Ok();

}

// This works with Core 3.1

[HttpPost]
public async Task<IActionResult> PostAsync([FromBody] JObject jvalue)
{

// code here

return Ok();

}

//error return 

{"errors":{"":["Unexpected character encountered while parsing value: {. Path '', line 1, position 1."]},"type":"https://tools.ietf.org/html/rfc7231#section-6.5.1","title":"One or more validation errors occurred.","status":400,"traceId":"|8ab7b30f-40b939694d56c1ec."}

Answer 1

User711641945 posted

Hi Albertk89,

Why is JToken now not valid parameter?  

As part of the work to improve the ASP.NET Core shared framework, Newtonsoft.Json has been removed from the ASP.NET Core shared framework for asp.net core 3.x.

To reuse JToken,follow the steps below:

• Install the Microsoft.AspNetCore.Mvc.NewtonsoftJson package on nuget.

  Install-Package Microsoft.AspNetCore.Mvc.NewtonsoftJson
  

• Update Startup.ConfigureServices to call AddNewtonsoftJson.

  services.AddControllersWithViews().AddNewtonsoftJson();

Reference:

https://docs.microsoft.com/en-us/aspnet/core/migration/22-to-30?view=aspnetcore-3.1&tabs=visual-studio#newtonsoftjson-jsonnet-support

Best Regards,

Rena

Answer 2

User718448626 posted

Yes, that is what I did.   The JObject and JToken belongs to Newtonsoft library.  What I am confused is that in Core 3.1 JToken cannot be used as the parameter of the "Post", it just errors out during runtime.

May I know if there is an equivalent for the the two classes in System.Text.Json ?

Answer 3

User711641945 posted

Hi Albertk89,

May I know if there is an equivalent for the the two classes in System.Text.Json ?

I think you could try JsonDocument,refer to:

https://docs.microsoft.com/en-us/dotnet/standard/serialization/system-text-json-migrate-from-newtonsoft-how-to#jsondocument-and-jsonelement-compared-to-jtoken-like-jobject-jarray

Best Regards,

Rena