Sitecore WFFM MVC Custom Cross Control validation - validation

Question

Is there a way in Sitecore WFFM MVC to implement a custom validation on a field which is conditionally required based on the selection of another field
"DynamicValidationBase":- This is a attributerized validation where this validation is applied on the field, which does have the access to the form details(other controls on the form).
"FormCustomValidator":- This never gets triggered as this is a "MVC Form".
Ex:
<style>
div{padding:10px 0;}
ul{
list-style:none;
}
</style>
<div>
<label for="Email">Email:</label>
<input type="text" name="Email"/>
</div>
<div>
<label for="Phone">Phone:</label>
<input type="text" name="Phone"/>
</div>
<div>
<label for="IPrefer">I Prefer:</label>
<ul>
<li>
<input type="radio" id="rdo_email" checked="checked" name="rdoPreferType"/>
<label for="rdo_email">Email</label>
</li>
<li>
<input type="radio" id="rdo_phone" name="rdoPreferType"/>
<label for="rdo_phone">Phone</label>
</li>
</ul>
</div>

Answer 1

RequiredIfPopulatedAttribute -
First, a custom attribute is needed to decorate the custom field. This feeds necessary data from the form to the client side to build the validation and validation error message.
Custom Field Class -
Next, create a custom field that inherits from the desired field but add the attribute above to the Value property.
Custom Field View -
Add any customizations to the presentation in this mvc view. Ensure that the model is the custom class above. Save this .cshtml file with the other WFFM views.
Javascript -
Add the following js validators:
$scw.validator.addMethod()
$scw.validator.unobtrusive.adapters.add()
Sitecore updates -
Create a FieldType referencing the custom class in the MVC Type field.
Reference this new custom FieldType as the Type field in the Form Designer.
The form field’s Parameters field contains a list of values that feed the custom field’s properties.
Above is an outline of the steps to accomplish this. For illustrations, please see: https://soyouwannasitecore.wordpress.com/2016/10/27/sitecore-wffm-required-if-outlined/