title: MVC Entity Framework validation to prevent duplicate records
body: <p>Hi i'm new to MVC and EF so this may be a really simple question but what is the best way to prevent the user from trying to enter duplicate records?</p>
  
  <p>I have a simple look up table with one column which is the primary key. I'm creating a maintenance screen so admins can add extra items to the look up list. My controller looks like :</p>
  
  <pre><code>public ActionResult Index(string NewRow)
      {
          try
          {
              CaseType t = new CaseType { ID = NewRow };
              if (ModelState.IsValid)
              {
                  UOW.CaseTypes.Add(t);
                  UOW.Save();
              }
          }
          catch (Exception ex)
          {
              ModelState.AddModelError("", ex.Message);
          }
          return View(UOW.CaseTypes.All());
      }
  </code></pre>
  
  <p>Which stops the duplicate records and stops the yellow screen of death but the message displayed is : "An error occurred while updating the entries. See the inner exception for details." which is no good for the users. </p>
  
  <p>I was just wondering if there is a better way to catch the error.</p>