Add error message to @Html.ValidationSummary

Question

I'm using standard MVC3 Razor views with unobtrusive Javascript validation, using @Html.ValidationSummary to show them at the top of the form. If the standard validations (things like [Required]) pass, I then run some very custom client-side validation that fires when the user hits the Submit button. (The validation looks across a number of form elements to make sure that the proper set of them have been checked, etc., so it's not as simple as just creating a new custom validator for a single field).

I'd like the possible error(s) I construct there to be shown in the ValidationSummary list, but I can't figure out how to get the error message to appear there.

Answer 1

In client-side:

function YourCustomValidator() {
    // do your validation logic here via JavaScript
    return true; // or false based on your validation logic
}
$(document).ready(function () {
    // take your own form-selector like ("form", this)
    $("form", this).first().submit(function () {
        return (YourCustomValidator() && $(this).valid());
    });
});

OR In server-side:

Think you have a model like this:

public class Test {
    [Required]
    [StringLength(100)]
    public string FullName { get; set; }
}

and when you are validating it:

if(ModelState.IsValid) { // default validations run here
    if(/* some custom validations run here, there is an error about "FullName" */){
        // you should set the "key" for Model-Error to "FullName"
        ModelState.AddModelError("FullName","error-message goes here")
    }
    if(/* some custom validations run here, the error is global, not on "FullName" */){
        // you should set the "key" for Model-Error to an empty-string
        ModelState.AddModelError("","error-message goes here")
    }
    // also you can test for model-errors again like this:
    if(ModelState.IsValid) { // if you add any error above, this will be "false"

    }
}

Answer 2

You can do so just adding the Error Message to the ModelState should display the error message for you, provided that you have ValidationSummary() called on your view.

To add the error to the ModelState just do this:

ModelState.AddModelError("ColumnNameOrErrorMessageKeyInState","error message goes here")