I’m currently working on an API that should be adding a client in the database and basically my controller looks like this:

[ApiController]
[Route("api/[controller]")]
[Authorize()]
public class ClientController : ControllerBase
{
    private readonly IClientService ClientService;

    public ClientController(IClientService clientService)
    {
        this.ClientService = clientService;
    }

    [HttpPost("AddClient")]
    [Consumes("application/json")]
    public async Task<IActionResult> AddClient([FromBody]AddNewClientDTO client)
    {
        if (ModelState.IsValid)
        {
            await this.ClientService.AddClient(client);
        }

        return Ok();
    }
}

However this code is not working. I have tried multiple things and the only time it’s working is when I change the AddNewClientDTO to object or dynamic.

This API is being called via the Web interface which is a ASP.NET application. When the I fill out the form, the controller is making the API call which is being handled by API Gateway. For the gateway, I’m using Ocelot.

I also have authentication with Auth0, but for it I know it’s working as I’m not having issues with the GET for example. When I was testing to make the call via Postman it’s working and the client is being added in the database.

Here is the code that is calling the API:

var jsonModel = JsonConvert.SerializeObject(model);

using (HttpClient httpClient = new HttpClient())
{
    httpClient.DefaultRequestHeaders.Accept.Clear();
    httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
    httpClient.DefaultRequestHeaders.Add("authorization", $"Bearer {authenticationProviderKey}");
    httpClient.DefaultRequestHeaders.Add("client", jsonModel);
    StringContent kpcontent = new StringContent(jsonModel, Encoding.UTF8, "application/json");

    var kpresponse = await httpClient.PostAsync("https://localhost:7022/api/Client/AddClient", kpcontent);
}

When I’m using Postman to manually pass the client parameters, I’m getting the AddNewClientDTO object when calling the API, but when using the web app, it’s returning “Error 400 – Bad Request” and the only way I can make it working is when I use dynamic or object.

How can I make the AddClient method to receive the AddNewClientDTO object instead of dynamic? Am I doing something wrong when calling the API?