HttpClient {StatusCode: 415, ReasonPhrase: 'Unsupported Media Type'

Question

I try to call my API in a method but i get the error: {StatusCode: 415, ReasonPhrase: 'Unsupported Media Type'. I have been looking around and found a lot of people have had the same problem but it have been solved by adding the media type when creating the StringContent. I have set the string content and i still get the error.

Here is my method where i try to call the API:

    [HttpGet]
    public async Task<ActionResult> TimeBooked(DateTime date, int startTime, int endTime, int id)
    {

        var bookingTable = new BookingTableEntity
        {
            BookingSystemId = id,
            Date = date,
            StartTime = startTime,
            EndTime = endTime
        };

        await Task.Run(() => AddBooking(bookingTable));

        var url = "http://localhost:60295/api/getsuggestions/";

        using (var client = new HttpClient())
        {
            var content = new StringContent(JsonConvert.SerializeObject(bookingTable), Encoding.UTF8, "application/json");
            var response = await client.GetAsync(string.Format(url, content));
            string result = await response.Content.ReadAsStringAsync();

            var timeBookedModel = JsonConvert.DeserializeObject<TimeBookedModel>(result);

            if (response.IsSuccessStatusCode)
            {
                return View(timeBookedModel);
            }
        }

And my API method:

    [HttpGet]
    [Route ("api/getsuggestions/")]
    public async Task<IHttpActionResult> GetSuggestions(BookingTableEntity bookingTable)
    {
        //code
    }

I have been using the same code to call my other method and it has been working fine except in this case. I don't understand the difference between them.

Here is an example where i use basicly the same code and it works.

[HttpGet]
    public async Task<ActionResult> ChoosenCity(string city)
    {
        try
        {
            if (ModelState.IsValid)
            {
                var url = "http://localhost:60295/api/getbookingsystemsfromcity/" + city;

                using (var client = new HttpClient())
                {
                    var content = new StringContent(JsonConvert.SerializeObject(city), Encoding.UTF8, "application/json");
                    var response = await client.GetAsync(string.Format(url, content));
                    string result = await response.Content.ReadAsStringAsync();

                    var bookingSystems = JsonConvert.DeserializeObject<List<BookingSystemEntity>>(result);
                    var sortedList = await SortListByServiceType(bookingSystems);

                    if (response.IsSuccessStatusCode)
                    {
                        return View(sortedList);
                    }
                }
            }
        }

        catch (Exception ex)
        {
            throw ex;
        }

        return RedirectToAction("AllServices");
    }

And the API:

[HttpGet]
    [Route("api/getbookingsystemsfromcity/{city}")]
    public async Task<IHttpActionResult> GetBookingSystemsFromCity(string city)
    {
        //code
    }

Answer 1

Web API expects client to specify Content-Type header, but you cannot specify this header for HttpClient while making GET request because it doesn't have a body. Even though you specified application/json in StringContent you passed the object incorrectly into request. Consider using POST to fix you problem. And it's a common practice to use POST to transfer complex objects.

Update api to accept POST

[HttpPost]
[Route ("api/getsuggestions/")]
public async Task<IHttpActionResult> GetSuggestions(BookingTableEntity bookingTable)

Update request code

var content = new StringContent(JsonConvert.SerializeObject(city), Encoding.UTF8, "application/json");
var response = await client.PostAsync(url, content);
string result = await response.Content.ReadAsStringAsync();

Note

Don't dispose HttpClient on each request, it's intended to be reused.