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"

    }
}