400 Bad Request submitting Json to WebApi via HttpClient.PutAsync

Question

Normally, serialized objects would be used from the services to the webapi calls but in this instance I have to use a json representation for the call.

The process would be to deserialize the json to the proper class, then process as usual.

HttpClient Put

Method is called from within a console app

   public async Task<ApiMessage<string>> PutAsync(Uri baseEndpoint, string relativePath, Dictionary<string, string> headerInfo, string json)
    {
        HttpClient httpClient = new HttpClient();
        if (headerInfo != null)
        {
            foreach (KeyValuePair<string, string> _header in headerInfo)
                _httpClient.DefaultRequestHeaders.Add(_header.Key, _header.Value);
        }

        httpClient.DefaultRequestHeaders.Accept.Clear();
        httpClient.DefaultRequestHeaders.Accept.Add(
            new MediaTypeWithQualityHeaderValue("application/json-patch+json"));

        var content = new StringContent(json, Encoding.UTF8, "application/json-patch+json");

        var response = await httpClient.PutAsync(CreateRequestUri(relativePath, baseEndpoint), content);
        var data = await response.Content.ReadAsStringAsync();

        ... 
    }

Endpoint

The call never hits the endpoint. The endpoint is hit if I remove the [FromBody] tag but as expected, the parameter is null. There seems to be some sort of filtering happening.

    [HttpPut()]
    [Route("")]
    [SwaggerResponse(StatusCodes.Status200OK)]
    [SwaggerResponse(StatusCodes.Status400BadRequest)]
    public async Task<IActionResult> UpdatePaymentSync([FromBody] string paymentSyncJson)
    {
        if (string.IsNullOrEmpty(paymentSyncJson))
            return BadRequest();
         //hack: don't have access to models so need to send json rep
         var paymentSync = JsonConvert.DeserializeObject<PaymentSync>(paymentSyncJson);
       ....
    }

This is the json payload. I thought [FromBody] took care of simple types but this is proving me wrong.

  {
    "paymentSyncJson": {
      "id": 10002,
      "fileName": "Empty_20190101.csv",
      "comments": "Empty File",
      "processingDate": "2019-01-02T19:43:11.373",
      "status": "E",
      "createdDate": "2019-01-02T19:43:11.373",
      "createdBy": "DAME",
      "modifiedDate": null,
      "modifiedBy": null,
      "paymentSyncDetails": []
    }
  }

Answer 1

Your payload is not a string, it's a json, that's why the runtime can't parse the body to your requested string paymentSyncJson .

To solve it, create a matching dto which reflects the json

public class PaymentDto
{
    public PaymentSyncDto PaymentSyncJson { get; set; }
}
public class PaymentSyncDto
{
    public int Id { get; set; }
    public string FileName { get; set; }
    public string Comments { get; set; }
    public DateTime ProcessingDate { get; set; }
    public string Status { get; set; }
    public DateTime CreatedDate { get; set; }
    public string CreatedBy { get; set; }
    public DateTime ModifiedDate { get; set; }
    public string ModifiedBy { get; set; }
    public int[] PaymentSyncDetails { get; set; }
}

Then use it in the controller method to read the data from the request body

public async Task<IActionResult> UpdatePaymentSync([FromBody] PaymentDto payment)

Answer 2

Just expanding on my Comment.

The OP did:

[HttpPut()]
[Route("")]
[SwaggerResponse(StatusCodes.Status200OK)]
[SwaggerResponse(StatusCodes.Status400BadRequest)]
public async Task<IActionResult> UpdatePaymentSync([FromBody] string paymentSyncJson)
{
    if (string.IsNullOrEmpty(paymentSyncJson))
        return BadRequest();
     //hack: don't have access to models so need to send json rep
     var paymentSync = JsonConvert.DeserializeObject<PaymentSync>(paymentSyncJson);
   ....
}

Where they have put [FromBody] string paymentSyncJson , FromBody will try and deserialise into the type you specify, in this case string . I suggest doing:

public async Task<IActionResult> UpdatePaymentSync([FromBody] JObject paymentSyncJson)

Then you can change this line:

var paymentSync = JsonConvert.DeserializeObject<PaymentSync>(paymentSyncJson);

To:

var paymentSync = paymentSyncJson.ToObject<PaymentSync>();