public async Task addUitnodiging(string username, string wishlist)
{
HttpClient client = new HttpClient();
var myContent = JsonConvert.SerializeObject(username);
var stringContent = new StringContent(myContent, UnicodeEncoding.UTF8, "application/json");
var result = await client.GetStringAsync(baseUrl + "/gebruiker/" + username);
Gebruiker gebruiker = JsonConvert.DeserializeObject <Gebruiker>(result);
gebruiker.addUitnodiging(wishlist);
myContent = JsonConvert.SerializeObject(gebruiker);
stringContent = new StringContent(myContent, UnicodeEncoding.UTF8, "application/json");
var rst = await client.PutAsync(baseUrl + "/gebruiker/" + gebruiker.name, stringContent);
rst.EnsureSuccessStatusCode();
}