public IActionResult Post([FromBody] JsonFormVal value)
 {
     if (!ModelState.IsValid)
     {
         //throw new System.InvalidOperationException("잘못된 값");
         return(BadRequest(ModelState)); //400 BadRequest
     }
     value.Id++;
     // 데이터 저장 ,
     return(CreatedAtAction("Get", new { id = value.Id }, value));
 }
 public void Put(int id, [FromBody] JsonFormVal value)
 {
 }