Question

I have 2 Action methods in one controller,

Index:

public ActionResult Index(string url)
{
   // take the url as a param and do long tasks here  
   ViewBag.PageTitle = "title";  
   ViewBag.Images = "images";  
   // and some more view bags  
   return View();
}

This index view contains a form which post to another method in the same controller.

public ActionResult PostMessage(string msg, string imgName)  
{  
   // save data in the db
   // but on error I want to navigate back to the Index view but without losing data the  user fielded before submit the form.
  // Also need to pass an error message to this index view to show
}

How to return back to Index view if something went wrong in the PostMessage method, and also don’t clear the form fields, plus showing an error message which the PostMessage method specified.

I need to know the best practice for doing such a scenario.

Answer 1

The best approach is usually to create a ViewModel type for your form. Add attributes to the properties of that model to define what would make it “wrong.” Make your form use methods like @Html.TextBoxFor the various fields. Then have your PostMessage class take an object of that type, rather than taking the message and image name directly. Then you can validate the model and return the view again if the model is invalid.

See http://weblogs.asp.net/scottgu/archive/2010/01/15/asp-net-mvc-2-model-validation.aspx for some code examples following this pattern.