ASP.NET HttpClient request returns 409 Error

Question

I am doing a HTTP call like so:

[HttpGet]
public HttpResponseMessage updateRegistrant(string token, string registrantId, string firstname, string lastname, string postalCode, string phoneNumber, string city, string email)
{
    using (HttpClient httpClient = new HttpClient())
    {
        httpClient.BaseAddress = new Uri("https://api.example.com/v1/registrants/" + registrantId + "/");
        httpClient.DefaultRequestHeaders.Accept.Clear();
        httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
        httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);

        HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Put, "person/contact-information");

        request.Content = new StringContent("{\"firstName\":\"" + firstname + "\", \"lastName\":\"" + lastname + "\", \"phones\":[{\"phone\":\"" + phoneNumber + "\", \"type\":\"Home\", \"primary\":true}], \"emails\":[{\"email\":\"" + email + "\", \"type\":\"Personal\", \"primary\":true}], \"addresses\":[{\"city\":\"" + city + "\", \"zipCode\":\"" + postalCode + "\"}]}", Encoding.UTF8, "application/json");

        //request.Content = new StringContent("{\"firstName\":\"" + firstname + "\", \"lastName\":\"" + lastname + "\"}", Encoding.UTF8, "application/json");

        HttpResponseMessage response = httpClient.SendAsync(request).Result;

        return response;
    }
}

Now when I run this method, I get 409 Error call, however if I comment out the first request.Content and uncomment the second request.Content it works, I get response code of 200.

I would assume that these are causing the 409 error:

\"phones\":[{\"phone\":\"" + phoneNumber + "\", \"type\":\"Home\", \"primary\":true}]

But why and how do I fix this?

Answer 1

Rather than trying to manually build the JSON string, consider an approach like this.

string firstname = "";
string lastName = "";
string phoneNumber = "";
string primary = "";
string phoneNumber2 = "";

var registrant = new
{
    firstName = firstname,
    lastName = lastName,
    phones = new[]
    {
        new { phone = phoneNumber, type = "Home", primary = true },
        new { phone = phoneNumber2, type = "Work", primary = false }
    }
};

JavaScriptSerializer js = new JavaScriptSerializer();
string jsonData = js.Serialize(registrant);

Structuring your request in a way that you can more easily self-troubleshoot, may help you answer your own question and find out specifically which part of the data is causing the error. It will also help you avoid any basic typos when you're building the JSON.

The 409 could be anything. Check the response object for a human readable error message that might contain more information. In general, it means that your updated data conflicts with something. The phones, the addresses, etc. Start with a known working request and add elements one at a time.

If you can narrow down specifically which data is causing the server to return 409, then go back and look more carefully at their API documentation. You're on the right track.