PostAsync 参数始终为空

Question

I am calling an API Post method, however, I am not sure what I am doing wrong but the value in the API is always null. The method I am calling the API from is below. When I hit this I can see Ids is list of ints with 5 values for example.

private void Save(List<int> Ids)
{
  var myAPI = ConfigurationManager.AppSettings["MyAPI"];

  string myIds = string.Join(",", Ids);

  using (var client = new HttpClient())
  {

    int result = client.PostAsync(myAPI, new { test = myIds }, new JsonMediaTypeFormatter())
                        .Result
                        .Content
                        .ReadAsAsync<int>()
                        .Result;
  }
}

My API signature is like below - with a breakpoint on I can see it is getting hit but test the parameter I am trying to pass is always null

    [HttpPost]
    [Route("api/MyController/SaveData")]
    public HttpResponseMessage SaveData([FromBody]List<string> test)
    {
        try
        {
        //Rest of method removed for brevity

I have tried removing the [FromBody] Annotation from the WebAPI controller but test still is getting null with breakpoint in the SaveData API method

Answer 1

Try this:

private void Save(List<int> Ids)
{
    var myAPI = ConfigurationManager.AppSettings["MyAPI"];

    using (var client = new HttpClient())
    {
        var requestBody = JsonConvert.SerializeObject(Ids);
        var postRequest = new StringContent(requestBody, Encoding.UTF8, "application/json");

        var response = client.PostAsync(myAPI, postRequest).GetAwaiter().GetResult();
        var rawResponse = response.Content.ReadAsStringAsync().GetAwaiter().GetResult();
        // Do something with the answer
    }
}

I also suggest to make the method private Task Save and replace .GetAwaiter().GetResult(); with await in front of that calls.

Answer 2

In my case i used System.Web.Http.ApiController instead of System.Web.Mvc.Controller. So over all code looks like

public class YourAppController : ApiController
{
    [System.Web.Http.Route("publish-message")]
    public HttpResponseMessage Post([System.Web.Http.FromBody] string msges)
    {
        //Your Code
        return Request.CreateResponse(HttpStatusCode.OK, "");

    }
}


public async Task<string> PublishMessageCall(string publishMessage){                
        var returnval = "";
        string httpWebRqst = "http://localhost:543134535/publish-message";

        using (HttpClient myClient = new HttpClient())
        {
            var jsonString = JsonConvert.SerializeObject(publishMessage);
            var content = new StringContent(jsonString, Encoding.UTF8, "application/json");

            var response = await myClient.PostAsync(httpWebRqst, content);

            var responseString = await response.Content.ReadAsStringAsync();

        }
        return await Task.FromResult(returnval);}