How to configure custom validation rules for kendo grid editor - kendo-grid

Question

We have ASP.NET MVC application using Telerik UI for ASP.NET MVC. On the page is set up a grid with popup editor, by kendo html helper.
Now I need to configure some custom validation rules for popup editor form. I can't find a way how to do it.
In validator documentation can be seen to get validator reference from $("form"). But there is no form in grid popup
If I configure rules on validator taken from $("gridName").kendoValidator().data("kendoValidator"), such rules are simply not fired when saving editor changes
If I get reference to validator from some editor container gridOnEditEvent.container.find("#editorcontent").kendoValidator().data("kendoValidator"), for example, I can extend rules, validate and send form data manually, but standard save button of the popup editor doesn't reflect such configuration
How can extend validation rules of the grid popup editor validator?

Answer 1

Kendo widgets built with an HTML helper, such as the Grid, initialize their own internal Validator. Custom rules must be added to the Validator class itself in order to run in these inaccessible instances of the Validator. Telerik has an example of how to do this:
$.extend(true, kendo.ui.validator, {
rules: { // custom rules
productnamevalidation: function(input, params) {
if (input.is("[name='ProductName']") && input.val() != "") {
input.attr("data-productnamevalidation-msg", "Product Name should start with capital letter");
return /^[A-Z]/.test(input.val());
}
return true;
}
},
messages: { //custom rules messages
productnamevalidation: function(input) {
// return the message text
return input.attr("data-val-productnamevalidation");
}
}
});