Hello,

1. Create a javascript module like below for your custom field

2. Create a qweb template for the custom field

3. You can access all fields on the form like shown below.

4. Then you can pass the value to the template
   Finally add the field to the form like <widget type="customwidget"/>
   
   
   

The Script

odoo.define('module.module_title', function (require) {

"use strict";

var core = require('web.core');

var common = require('web.form_common');

var CustomWidget = common.FormWidget.extend({

    template: 'CustomWidget',

     events: {

    },

    start: function() {

      var self=this;

// You can get the values of all fields on the form like this

      var field_value=self.field_manager.get_field_value('field_name');

self.color_class=field_value;

        this._super();

    },

    })

core.form_custom_registry.add('customwidget', CustomWidget);

return {

  CustomWidget:CustomWidget,

};

});

The Template

  <t t-name="CustomWidget">

<td t-att-style=""  t-att-class="widget.color_class">Some Thig</td>    

    </t>

To display the widget on the form view

<widget type="customwidget"/>

Thank You

Hello,

This module creates a new widget for adding map.You can refer it