HttpClient POST response is not returning

I have created an http call to an API using httpclient. Request is sending to the end point but response is not receiving. No errors

public static async Task<List<BookingFeeResponseModel>> GetBookingFeeRuleDetailsAsync(string postData)
        {
            try
            {
                HttpRequestMessage request = GetRequest(BOOKING_FEE_RULES_API_URL, postData, HttpMethod.Post);
                var response = await _httpClient.SendAsync(request, CancellationToken.None);

                if (response.IsSuccessStatusCode)
                {
                    string responseContent = await response.Content.ReadAsStringAsync();
                    //JObject json = JObject.Parse(responseContent);

                    var bookingFeeRules = JsonConvert.DeserializeObject<List<BookingFeeResponseModel>>(responseContent);
                    return bookingFeeRules;
                }
            }
            catch (Exception ex)
            {
                Logger.Info($"Get Booking Fee Rule Details Err: {ex.Message}");
                throw;
            }
            return null;
        }

private static HttpRequestMessage GetRequest(string apiUrl, string postData, HttpMethod httpMethod)
        {
            var request = new HttpRequestMessage(httpMethod, apiUrl);
            request.Headers.Accept.Clear();
            request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
            request.Headers.Add("altHost", ALT_HOST);
            if(httpMethod != HttpMethod.Get)
                request.Content = new StringContent(postData, Encoding.UTF8, "application/json");
            return request;
        }

Here is the API which gets calling

        [HttpPost]
        public HttpResponseMessage GetBookingFeeAllRules([FromBody] BookingFeeRequestModel bookingFeeRequestModel)
        {
            try
            {
                Logger.Info("Getting Booking Fee All Rules");
                var bookingFeeRules = new List<EditRuleModel>();
                var mappedBookingFeeRules = new List<BookingFeeResponseModel>();

                var allRules = GetAllRules();
                var ruleIdArray = allRules.Where(r => r.ApplyOrder > 1700 && r.ApplyOrder < 1800)?.Select(a => a.Id).ToArray();
                GetBookingFeeRuleDetails(bookingFeeRequestModel, bookingFeeRules, mappedBookingFeeRules, ruleIdArray, allRules);
                mappedBookingFeeRules = mappedBookingFeeRules.Where(r => r.RuleModels != null)?.ToList();
                var result = Request.CreateResponse(HttpStatusCode.OK, mappedBookingFeeRules);
                return result;
            }
            catch (Exception ex)
            {
                Logger.Info("Error getting booking fee disclaimer {0}", ex);
                throw;
            }
        }

Can someone please help me with this.

I need to get the API response from GetBookingFeeAllRules. But now nothing is returning.
Is I am doing anything wrong here?

You have not provided some methods and models, so I built a simple example based on your logic, you can refer to it.

Model:

public class BookingFeeResponseModel
{ 
    public int Id { get; set; }
    public string Name { get; set; }
    public RuleModel RuleModels { get; set; }
}

public class BookingFeeRequestModel
{ 
    public string postData { get;set; }
}

public class EditRuleModel
{ 
    public int Id { get; set; }
}

public class RuleModel
{ 
    public int Id { get; set; }
    public int ApplyOrder { get; set; }
}

GetBookingFeeRuleDetailsAsync:

[HttpPost]
public async Task<List<BookingFeeResponseModel>> GetBookingFeeRuleDetailsAsync(string postData)
{
    try
    {
        HttpClient _httpClient = new HttpClient();
        HttpRequestMessage request = GetRequest("https://localhost:7247/api/Response", postData, HttpMethod.Post);
               
        var response = await _httpClient.SendAsync(request, CancellationToken.None);

        var ResultDetail = response.Content.ReadAsStringAsync().Result;

        if (response.IsSuccessStatusCode)
        {
            string responseContent = await response.Content.ReadAsStringAsync();
            //JObject json = JObject.Parse(responseContent);

            var bookingFeeRules = JsonConvert.DeserializeObject<List<BookingFeeResponseModel>>(responseContent);
            return bookingFeeRules;
        }
    }
    catch (Exception ex)
    {
        throw;
    }
    return null;
}
private static HttpRequestMessage GetRequest(string apiUrl, string postData, HttpMethod httpMethod)
{
    var request = new HttpRequestMessage(httpMethod, apiUrl);
    request.Headers.Accept.Clear();
    request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
    request.Headers.Add("altHost", "ALT_HOST");
    BookingFeeRequestModel bookingFeeRequestModel = new BookingFeeRequestModel() { postData = postData };
    if (httpMethod != HttpMethod.Get)
        request.Content = new StringContent(JsonConvert.SerializeObject(bookingFeeRequestModel), Encoding.UTF8, "application/json");
    return request;
}

In the GetRequest method, I use JsonConvert.SerializeObject(bookingFeeRequestModel) to replace postData, otherwise I will receive Bad Request and cannot enter GetBookingFeeAllRules. You can add breakpoints to see if you successfully get inside GetBookingFeeAllRules.

Also, you can add var ResultDetail = response.Content.ReadAsStringAsync().Result; before if (response.IsSuccessStatusCode) to see if there is an error message.

CreateResponse extension method:

public static IActionResult CreateResponse(this HttpRequest request, int status, object content)
{
    return new ObjectResult(content)
    {
        StatusCode = status
     };
}

GetBookingFeeAllRules:

[HttpPost]
public IActionResult GetBookingFeeAllRules([FromBody] BookingFeeRequestModel bookingFeeRequestModel)
{
    try
    {
        var bookingFeeRules = new List<EditRuleModel>();
        var mappedBookingFeeRules = new List<BookingFeeResponseModel>()
        { 
            new BookingFeeResponseModel(){ Id=1,Name = "Name1",RuleModels = new RuleModel(){ Id = 1,ApplyOrder = 1701} },
            new BookingFeeResponseModel(){ Id=2,Name = "Name2",RuleModels = new RuleModel(){ Id = 2,ApplyOrder = 1801} },
            new BookingFeeResponseModel(){ Id=3,Name = "Name3",RuleModels = new RuleModel(){ Id = 3,ApplyOrder = 1702} },
            new BookingFeeResponseModel(){ Id=4,Name = "Name4",RuleModels = new RuleModel(){ Id = 4,ApplyOrder = 1802} },
        };

        var allRules = GetAllRules();
        var ruleIdArray = allRules.Where(r => r.ApplyOrder > 1700 && r.ApplyOrder < 1800)?.Select(a => a.Id).ToArray();
        //GetBookingFeeRuleDetails(bookingFeeRequestModel, bookingFeeRules, mappedBookingFeeRules, ruleIdArray, allRules);
        mappedBookingFeeRules = mappedBookingFeeRules.Where(r => r.RuleModels != null)?.ToList();
                
        var result = Request.CreateResponse(200, mappedBookingFeeRules);
        return result;
    }
    catch (Exception ex)
    { 
        throw;
    }
}

private List<RuleModel> GetAllRules()
{
    List<RuleModel> ruleModel = new List<RuleModel>()
    {
        new RuleModel(){ Id = 1,ApplyOrder = 1701},
        new RuleModel(){ Id = 2,ApplyOrder = 1801},
        new RuleModel(){ Id = 3,ApplyOrder = 1702},
        new RuleModel(){ Id = 4,ApplyOrder = 1802},
    };
    return ruleModel;
}

You can first check whether the breakpoint of the called Api is hit, and then check whether the parameters can be received:

If there is no problem, you can debug step by step to ensure that there is no problem with each step:

If this breakpoint is not hit, you can view the corresponding error message to find out what the problem is:

If you don't find the problem, you can call your Api interface through Postman to see if the result is returned as you expected.

Hope this can help you.