I have a unit length that accept entering cm, inch and ft. I know how to set-up the input validation in one limit. Let say, I want to have max limit to 100cm. I can set the field validation to the following:

<input name="length" type="text" data-validate="{required:true, max:100}" />

And let say, I have a select field that contain the unit of length:

<select name="unit">
    <option value="cm">cm</option>
    <option value="inch">inch</option>
    <option value="ft">ft</option>

The problem is: If I enter 100ft or 100inch, the validation still pass. How can I adjust the max value when I switch the unit? So that 100ft or 100inch cannot pass the validation.

1 Answer 1


Finally it's just the matter of JS. First of all, modify the select list a bit:

<select name="unit">
    <option value="cm" data-conversion="0.03280840">cm</option>
    <option value="inch"data-conversion="0.08333333">inch</option>
    <option value="ft" data-conversion="1.00000000">ft</option>

Then, write the following JS. You can load it right under the select list, or via requirejs:

<script type="text/javascript">
    ], function($){
        //Change the value depends on the size unit        
        $("select[name='unit']").change(function () {
            var selected = $(this).find('option:selected');
            curr_price = selected.data("conversion");
            curr_max = $('input[name="length]"').rules("max");
            cm_price = $('option[value=cm]').data("price");
            new_max_range = curr_max * cm_price / curr_price;
            $('input[name="length]"').rules("remove", "max");
            $('input[name="productoptions[<?php echo $option->getOptionCode() ?>]"').rules("add", {
                    max: new_max_range

I just solved it long time ago, but forgot to answer it till now.

  • Which File ?? I Will Chnage attribute value inch to semi . Commented Feb 25, 2019 at 6:28
  • I forgot the exact file. Just remember on category product page
    – PY Yick
    Commented Feb 26, 2019 at 1:21

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