private void ButtonDodaj(object sender, RoutedEventArgs e)
 {
     if (TextBoxImie.Text != "" & TextBoxNazwisko.Text != "" & TextBoxPesel.Text != "" & DatePickerDataUrodzenia.Text != "" & TextBoxNumerTelefonu.Text != "")
     {
         var webAddr = "http://192.168.23.128:3000/api/events";
         var httpWebRequest = (HttpWebRequest)WebRequest.Create(webAddr);
         httpWebRequest.ContentType = "application/json; charset=utf-8";
         httpWebRequest.Method = "POST";
         using (var streamWriter = new StreamWriter(httpWebRequest.GetRequestStream()))
         {
             ListaKlientow Klient = new ListaKlientow();
             Klient.Imie = TextBoxImie.Text;
             Klient.Nazwisko = TextBoxNazwisko.Text;
             Klient.Pesel = int.Parse(TextBoxPesel.Text);
             Klient.DataUrodzenia = DatePickerDataUrodzenia.Text;
             Klient.NumerTelefonu = int.Parse(TextBoxNumerTelefonu.Text);
             string jsonString = JsonHelper.JsonSerializer(Klient);
             streamWriter.Write(jsonString);
             streamWriter.Flush();
         }
         var httpResponse = (HttpWebResponse)httpWebRequest.GetResponse();
         using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
         {
             var result = streamReader.ReadToEnd();
             System.Windows.MessageBox.Show(result);
         }
     }
     else
     {
         System.Windows.MessageBox.Show("Wypełnij wszystkie pola");
     }
 }