public void PutInstructor(int id, Instructor instr)
 {
     instr.Id = id;
     dbCtxt.Instructors.Attach(instr);
     dbCtxt.Entry(instr).State = System.Data.EntityState.Modified;
     dbCtxt.SaveChanges();
 }
        public HttpResponseMessage PostInstructor(Instructor instr)
        {
            if (!ModelState.IsValid)
            {
                throw new HttpResponseException(Request.CreateErrorResponse(HttpStatusCode.BadRequest, this.ModelState));
            }

            dbCtxt.Instructors.Add(instr);
            int records = dbCtxt.SaveChanges();

            var response = Request.CreateResponse(HttpStatusCode.Created, instr);
            response.Headers.Location = new Uri(Url.Link(ODataRouteNames.GetById, new { Controller = "Instructors", Id = instr.Id }));
            return response;
        }