ValidationSummary displays duplicate messages

Question

If two of textboxes fail validation at once then the ValidationSummary displays the same message twice.

Am I doing something wrong? Or is there a setting I can change to hide duplicate messages?

I have broken it down to the simplest example:

View:

@model MyModel
@Html.ValidationSummary()
@Html.TextBoxFor(model => model.A)
@Html.TextBoxFor(model => model.B)

Model:

public class MyModel : IValidatableObject
{
    public int A { get; set; }
    public int B { get; set; }

    public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
    {
        //Some logic goes here.        
        yield return new ValidationResult("Validation failed", new[] { "A", "B" });
    }
}

Result:

enter image description here

rouen · Accepted Answer · 2011-10-14T17:46:12.827

They are not duplicate from the point of view of ValidationSummary - you are assigning model state error to both fields A and B, so there must be 2 errors in validation summary. It doesnt "know" that they are the same.

Easy solutions :

assign model only to one of them
exclude property-assigned errors from summary - Html.ValidationSummary(true)

A little bit harder solution :

make your own ValidationSummary helper, call standard validation summary logic in it, and then filter the result in "select distinct" way (linq is your friend here).

EDIT:

something like this for example :

public static class ValidationExtensions
{
    public static MvcHtmlString FilteredValidationSummary(this HtmlHelper html)
    {
        // do some filtering on html.ViewData.ModelState 
        return System.Web.Mvc.Html.ValidationExtensions.ValidationSummary(html);
    }
}

Thanks, I have managed to create my custom helper and it is working great for now. The only problem is that most of it hard coded. You mentioned "standard validation summary logic". Did you have anything specific in mind or was it just a general statement? — Buh Buh, Oct 14 '11 at 14:27

Stuart Dobson · Answer 2 · 2012-04-24T04:22:51.223

Whack this is your View

<ul class="validation-summary-errors">
    @{
        string errorMessage = "", previousError = "";
        foreach (ModelState modelState in (ViewContext.ViewData.ModelState.Values)){

            foreach (ModelError modelError in modelState.Errors)
            {
                errorMessage = modelError.ErrorMessage;
                if (errorMessage != previousError)
                {
                    <li>@modelError.ErrorMessage</li>
                    previousError = modelError.ErrorMessage;
                }                            
            }    
        }
    }
</ul>

You might be able to improve this as it only works when 2 consecutive errors are the same, if it jumbles the order this might not work, but this will start you off. I suppose you could build an array of error messages and check the error off it each run through, but this solution seems to work most of the time.

This particular solution works better if you use a List of errors. As you loop through the errors, use list.Contains() to check if you have already processed an error. If you have not, put it in the list and then display it with

Yaschur · Answer 3 · 2011-10-14T13:24:07.767

ValidationSummary method returns property-level and model-level errors. It just enumerates all validation messages if you don't specify any arguments.

You can: 1) Use different message for field A and B

// logic here
yield return new ValidationResult("Validation failed for left field", new[] { "A" });
// logic here
yield return new ValidationResult("Validation failed for right field", new[] { "B" });

or, in your view

2) Call ValidationSummary with excludePropertyErrors argument set to true - ValidationSummary(true). And place call Html.ValidationMessage[For] near each of your fields.

UPDT: ... and third case:

In your model add common message (model-level):

//logic here
yield return new ValidationResult("Validation failed");
yield return new ValidationResult("any text or empty string", new[] { "A", "B" });

In your view exclude property messages but don't add ValidationMessage for fields:

@model MyModel
@Html.ValidationSummary(true)
@Html.TextBoxFor(model => model.A)
@Html.TextBoxFor(model => model.B)

So you'll get single message and both red boxes.

Thanks. Excluding ALL property errors seams a bit extreame when it is only one pair of fields that are causing me a problem. I don't understand why they would have built in a method for validating multiple fields which has such an obvious problem. — Buh Buh, Oct 14 '11 at 14:30
I agree it's not much convenient in situation like yours. But typical usage validation helper is `ValidationSummary(true)` with 'ValidationFor' like `@model MyModel @Html.ValidationSummary(true) @Html.TextBoxFor(model => model.A) @Html.ValidationFor(model => model.A) @Html.TextBoxFor(model => model.B) @Html.ValidationFor(model => model.B)` — Yaschur, Oct 14 '11 at 16:08

ValidationSummary displays duplicate messages

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