Enabling MVC client side validation - asp.net-mvc

Question

I have
<add key="ClientValidationEnabled" value="true" />
<add key="UnobtrusiveJavaScriptEnabled" value="true" />
in my config and
Html.EnableClientValidation(true);
Html.EnableUnobtrusiveJavaScript(true);
in my view and
<script src="~/js/jquery.validate.min.js"></script>
<script src="~/js/jquery.validate.unobtrusive.min.js"></script>
are in the HTML source (as is jQuery) (no JS errors in the browser)
I have one form element with [Required] and the form element seems to be rendering OK with the associated data- attributes
<div class='form-group'>
<label class="col-md-2 control-label" for="Username">en-gb(Username)</label>
<div class='col-md-10'>
<div class='input-group'>
<div class='input-group-addon'><span class='fa fa-user'></span></div>
<input class="input-validation-error form-control" id="Username" name="Username" type="text" value="" />
</div>
<span class="field-validation-error help-block" data-valmsg-for="Username" data-valmsg-replace="true">en-gb(The en-gb(Username) field is required.)</span>
</div>
</div>
But no client side validation is occurring; the form is always submitted to the server.
What am I missing? What should I be checking?
Edit
TextBoxFor is in System.Web.Mvc.Html.InputHelpers and calls TextBoxHelper which in turn calls InputHelper in the same file. This calls
htmlHelper.GetUnobtrusiveValidationAttributes(name, metadata) which looks like this:
public IDictionary<string, object> GetUnobtrusiveValidationAttributes(string name, ModelMetadata metadata)
{
Dictionary<string, object> results = new Dictionary<string, object>();
// The ordering of these 3 checks (and the early exits) is for performance reasons.
if (!ViewContext.UnobtrusiveJavaScriptEnabled)
{
return results;
}
FormContext formContext = ViewContext.GetFormContextForClientValidation();
if (formContext == null)
{
return results;
}
string fullName = ViewData.TemplateInfo.GetFullHtmlFieldName(name);
if (formContext.RenderedField(fullName))
{
return results;
}
formContext.RenderedField(fullName, true);
IEnumerable<ModelClientValidationRule> clientRules = ClientValidationRuleFactory(name, metadata);
UnobtrusiveValidationAttributesGenerator.GetValidationAttributes(clientRules, results);
return results;
}
(Source: http://aspnetwebstack.codeplex.com/SourceControl/changeset/view/5cb74eb3b2f3#src/System.Web.Mvc/HtmlHelper.cs)
The problem I have is that formContext.RenderedField(fullName) returns true and therefore no validation attributes are added to my input element.

Answer 1

In your views, are you rendering the following code?
#section Scripts {
#Scripts.Render("~/bundles/jqueryval")
}
Assuming you're using the default project template, you'll need to include that within the view that you're rendering to enable client side validation... Alternatively, add Scripts.Render("~/bundles/jqueryval") to the bottom of your layout file to enable it across all your views.
Also do ensure that bundles/jqueryval is defined in the Bundles configuration file.

Answer 2

formContext.RenderedField(fullName) was a red herring, I really don't know what all that was about.
The problem is that I've subclassed the ValidationAttribute classes in order to provide globalisation with lookup from a database rather than from resx. This means that they do not appear in the ModelMetadata.
One solution is to implement the interface System.Web.Mvc.IClientValidatable on the overridden attributes. However, the base classes do not implement this interface, so they must be configuring client side validation by some other mechanism -- and it's this other mechanism that isn't smart enough to pick up subclasses of the out-of-the-box ValidationAttributes.