How to figure out which key of ModelState has error

Question

How do I figure out which of the keys in ModelState that contains an error when ModelState.IsValid is false? Usually I would just hover the mouse thru the ModelState.Values list checking item by item for error count > 0. But now I'm working on a view that has some lists of complex objects, totalling 252 ModelState items(each item of each object of each list has an entry on ModelState.Keys).

So, is there an easier way to point out the error source?

Answer 1

You can check the ViewData.ModelState.Values collection and see what are the Errors.

[Httpost]
public ActionResult Create(User model)
{
   if(ModelState.IsValid)
   {
     //Save and redirect
   }
   else
   {
     foreach (var modelStateVal in ViewData.ModelState.Values)
     {
       foreach (var error in modelStateVal.Errors)
       {               
          var errorMessage = error.ErrorMessage;
          var exception = error.Exception;
          // You may log the errors if you want
       }
     }
   }         
   return View(model);
 }
}

If you really want the Keys(the property name), You can iterate through the ModelState.Keys

foreach (var modelStateKey in ViewData.ModelState.Keys)
{
    var modelStateVal = ViewData.ModelState[modelStateKey];
    foreach (var error in modelStateVal.Errors)
    {
        var key = modelStateKey; 
        var errorMessage = error.ErrorMessage;
        var exception = error.Exception;
        // You may log the errors if you want
    }
}

Answer 2

ModelState.Values.SelectMany(v => v.Errors);

is considered cleaner.