Issue with RESTful webservice +JSON+SQL stored procedure project
<p>I know for a fact that there is something I miss. My whole project is somewhat copy&amp;paste of various "how to..."s, my knowledge of C# is basic at best and I need to have it working since our standard web service software is RESTful only when sending.</p>

<p>My main problem is that all solutions I've stumbled upon are actually code snippets, which don't work for me - my C# knowledge is basic so I don't understand how it all works, much less troubleshoot it. I'm pretty sure I'm not even capturing the JSON that's being posted with incoming request. But OTOH I may be wrong.</p>

<p>Requirement: something that works off IIS on WS2012R2, can accept JSON files via HTTPPost, dump content into a SQL Server table and return Id for the row that just was created to the sender of the JSON. I will have to build on it to get full-blown web service that sends and receives multiple JSON files containing different data, all have to end up in SQL Server.</p>

<p>What I have:</p>

<p>Class:</p>

<pre><code>    namespace NA.Models
{
    public class Note
    {
        public Note() { }

        //public Guid id { get; set; }
        public static string Client { get; set; }
        public static int Case { get; set; }
        public static string Text { get; set; }
        public static int NoteId { get; set; }
        public static string R1 { get; set; }
        public static string R2 { get; set; }
        public static string S1 { get; set; }
        public static DateTime Date { get; set; }
        public static bool Type { get; set; }
      }
    }
</code></pre>

<p><strong>Interface</strong>:</p>

<pre><code>    namespace NA.Models
{
    interface INoteRepository
    {
        IEnumerable&lt;Note&gt; GetAll();
        void Add(Note item);
    }
}
</code></pre>

<p>Repository:</p>

<pre><code>namespace NA.Models
{
  class NoteDataRepository : INoteRepository
  {
     public void Add(Note item)
     {
        if (item == null)
        {
            throw new ArgumentNullException("item");
        }
        else
        {
            String strConnString = ConfigurationManager.ConnectionStrings["conString"].ConnectionString;
            SqlConnection con = new SqlConnection(strConnString);
            SqlCommand cmd = new SqlCommand();
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.CommandText = "BL_IntegrationInsertNote";
            cmd.Parameters.Add("@Client", SqlDbType.VarChar).Value = item.Client.Trim();
            cmd.Parameters.Add("@Case", SqlDbType.VarChar).Value = item.case;
            cmd.Parameters.Add("@Text", SqlDbType.VarChar).Value = item.Text.Trim();
            cmd.Parameters.Add("@When", SqlDbType.DateTime).Value = item.Date;
            cmd.Parameters.Add("@Ext", SqlDbType.Bit).Value = item.Type;
            cmd.Parameters.Add("@return", SqlDbType.Int).Direction = ParameterDirection.Output;
            cmd.Connection = con;

            try
            {
                con.Open();
                cmd.ExecuteNonQuery();
                string id = cmd.Parameters["@return"].Value.ToString();
                string lblMessage = null;
                lblMessage = "Record inserted successfully. ID = " + id;
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                con.Close();
                con.Dispose();
            }
        }    
        return item;
    }

    IEnumerable&lt;Note&gt; INoteRepository.GetAll()
    {
        throw new NotImplementedException("getitems");
    }
}
}
</code></pre>

<p>Controller:</p>

<pre><code>namespace NA.Controllers
{
   public class NC : ApiController
   {
      [Route("AddNote")]
      [HttpPost]
    public HttpResponseMessage PostNote(List&lt;Note&gt; item)
    {
        //NoteJson deserializednote = JsonConvert.DeserializeObject&lt;NoteJson&gt;(item);
        //Note notesdata = new Note(item);
        //foreach (deserializednote   
        NotesAccept.Models.INoteRepository Repository = new NotesAccept.Models.NoteDataRepository();
        item = Repository.Add(item);
        var response = Request.CreateResponse &lt; NotesAccept.Models.Note&gt;(HttpStatusCode.Created, item);

        return response;
    }
   }
}
</code></pre>

<p>When trying to send test json to the service I get an error in return:</p>

<blockquote>
  <p>500: Internal server error, Value cannot be null at Parameter item</p>
</blockquote>

<p>This is posttestserver.com dump of request sent:</p>

<pre><code>Headers (Some may be inserted by server)
REQUEST_URI = /post.php
QUERY_STRING = 
REQUEST_METHOD = POST
GATEWAY_INTERFACE = CGI/1.1
REMOTE_PORT = 56926
REMOTE_ADDR = ip
HTTP_CONNECTION = close
HTTP_CACHE_CONTROL = max-age=259200
HTTP_X_FORWARDED_FOR = 172.16.3.87
HTTP_VIA = 1.1 koenig.local (squid/3.3.13)
HTTP_EXPECT = 100-continue
CONTENT_LENGTH = 153
HTTP_HOST = posttestserver.com
HTTP_ACCEPT = application/json
CONTENT_TYPE = application/json
UNIQUE_ID = Vri0cUBaMGUAABvGeesAAAAL
REQUEST_TIME_FLOAT = 1454945393.4611
REQUEST_TIME = 1454945393

No Post Params.

== Begin post body ==
[{
    "Client": "Client1",
    "Case": 1,
    "Text": "Text",
    "NoteId": 2,
    "R1": "R1",
    "R2": "R2",
    "S1": "S1",
    "Date": "2015-10-26T09:06:46",
    "Type":"1"
}]
== End post body ==

Upload contains PUT data:
[{
    "Client": "Client1",
    "Case": 1,
    "Text": "Text",
    "NoteId": 2,
    "R1": "R1",
    "R2": "R2",
    "S1": "S1",
    "Date": "2015-10-26T09:06:46",
    "Type":"1"
}]
</code></pre>

<p>The above dump is from POST request which is identical to one I'm sending to my web service, with exception of URL. So can be treated as actual request.
And here is an IIS log:</p>

<blockquote>
  <p>Fields: date time s-ip cs-method cs-uri-stem cs-uri-query s-port cs-username c-ip cs(User-Agent) cs(Referer) sc-status sc-substatus
  sc-win32-status time-taken 2016-02-08 15:49:52 ::1 POST /blz/AddNote -
  80 - ::1 - - 500 0 0 2937</p>
</blockquote>