With ASP.NET MVC, how to display errors when outside controller?

Question

I'm trying to easily display errors in my View from anywhere in my code using :

@Html.ValidationSummary("", new { @class = "text-danger" })

Before MVC, I used :

ValidationError.Display("My error message");

And my ValidationError class looks like this:

public class ValidationError : IValidator
{
    private ValidationError(string message)
    {
        ErrorMessage = message;
        IsValid = false;
    }

    public string ErrorMessage { get; set; }
    public bool IsValid { get; set; }

    public void Validate()
    {
        // no action required
    }

    public static void Display(string message)
    {
        // here is the only part I would like to change ideally
        var currentPage = HttpContext.Current.Handler as Page;                
        currentPage.Validators.Add(new ValidationError(message));
    }

}

Now with MVC, to add errors, I can't use currentPage.Validators. I need to use ModelState but my problem is that I can't access ModelState when I'm not in the Controller. I tried accessing the controller or the ModelState via HttpContext but I've not found a way to do it. Any idea ?

ModelState.AddModelError("", "My error message");

yes for the Views but I would prefer not to modify the Models, I think the solution would become too "heavy/complex" — JP Tétreault
– JP Tétreault, Commented May 7, 2017 at 6:11
So can you modify ValidationError class? BTW where IValidator come from? — CodeNotFound
– CodeNotFound, Commented May 7, 2017 at 6:17
yes I can, my goal is to modify only the ValidationError class ideally, IValidator comes from using System.Web.UI; — JP Tétreault
– JP Tétreault, Commented May 7, 2017 at 6:39
I think your question need some updates :) How do you actually use ValidationError into your ASP.Net MVC ? Show us one action that use it. Is it necessary to always ValidationError or we can get rid of it? — CodeNotFound
– CodeNotFound, Commented May 7, 2017 at 6:43

Community · Accepted Answer · 2017-05-23 10:31:26Z

3

1. You can access it through `ViewContext.ViewData.ModelState`. Then use

@if (!ViewContext.ViewData.ModelState.IsValid)
{
    <div>There are some errors</div>
}

OR

ViewData.ModelState.IsValidField("NameOfInput")

get a list of inputs:

var errors = ViewData.ModelState.Where(n => n.Value.Errors.Count > 0).ToList();

2. You can pass your model state around like this:

public class MyClass{
    public static void errorMessage(ModelStateDictionary ModelState) {
        if (something) ModelState.AddModelError("", "Error Message");
    }
}

Use in controller:

MyClass.errorMessage(ModelState);

Use in view:

MyClass.errorMessage(ViewContext.ViewData.ModelState.IsValid);

3. `ModelState` via `ActionFilter`

public class ValidateModelAttribute : ActionFilterAttribute
{
     public override void OnActionExecuting(ActionExecutingContext filterContext)
     {
          if (filterContext.Controller.ViewData.ModelState.IsValid)
          {
                //Do Something 
          }
     }
}

You can get more help from this and this links.

edited May 23, 2017 at 10:31

CommunityBot

11 silver badge

answered May 7, 2017 at 2:02

Ashiquzzaman

5,3144 gold badges30 silver badges40 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

JP Tétreault Over a year ago

thanks ... I tried it but ViewData is only accessible when in Controller or View, it's not accessible when outside (example : a custom class responsible for importing some data). I think a workaround would be to pass the ModelState to that class in the Constructor but I was hoping to keep it more simple.

Ashiquzzaman Over a year ago

@JohnMarston I update my answer. can you please try?

JP Tétreault Over a year ago

thanks for the updated answer ... indeed this would work but my goal is to avoid passing the ModelState and getting it via HttpContext or something like that but it might not be possible ... it might sound picky but imagine you have 300 calls to .errorMessage() to change :P I marked your answer as helpful since it can be used as a workaround

Collectives™ on Stack Overflow

With ASP.NET MVC, how to display errors when outside controller?

1 Answer 1

1. You can access it through `ViewContext.ViewData.ModelState`. Then use

2. You can pass your model state around like this:

3. `ModelState` via `ActionFilter`

3 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1. You can access it through ViewContext.ViewData.ModelState. Then use

2. You can pass your model state around like this:

3. ModelState via ActionFilter

3 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related

1. You can access it through `ViewContext.ViewData.ModelState`. Then use

3. `ModelState` via `ActionFilter`