Passing ModelState to RedirectToAction into a ViewModel

Question

How can I pass back the validation errors I find when using DbEntityValidationException

            try
            {
                db.SaveChanges();
            }
            catch (DbEntityValidationException dbEx)
            {
                foreach (var validationErrors in dbEx.EntityValidationErrors)
                {
                    foreach (var validationError in validationErrors.ValidationErrors)
                    {
                        this.ModelState.AddModelError(validationError.PropertyName, 
                        validationError.ErrorMessage);
                    }
                }
                return RedirectToAction("AccessDetail", "Home", new { IDValue = access.ID });
            }

It appears that when I do this RedirectToAction my ModelState refreshes and I can not view the errors it found.

The AccessDetail populates a view model that has many different sources of data in it. So passing just the access to the View does not work.

I was looking at this question but it didn't fit my needs as my view is populated with a ViewModel

Answer 1

RedirectToAction helper method issues a 302 response to the client which makes the clients to issue a new GET request to the new url.

If you want to persist some data between these 2 requests, Use TempData.

TempData["Errors"] = yourListOfErrors;
return RedirectToAction("AccessDetail", "Home", new { IDValue = access.ID });

And in your GET action, read the TempData values and display it.

But If you do not want to do the RedirecToAction, You may simply return the viewmodel back to the view and if you have the ValidationSummary helper method, it will show the validation error messages.

simply use

return View(model);