Custom Sidecar field component for displaying related data

detail.hbs

{{!--
/*	File: ./custom/clients/base/fields/related-info/detail.hbs
*	Author: Angel Magaña -- cheleguanaco@cheleguanaco.com
*	Date: August 17, 2018
*
*	Description: Handlebars template for related info field component
*/
--}}

{{#each fields}}
    <div class="fieldset-field">
        {{fieldValue ../relatedData this}}
    </div>
{{/each}}

en_us.related-info.ext.php

<?php

/* File: ./custom/Extension/modules/Cases/Ext/Language/en_us.related-info.ext.php */

$mod_strings['LBL_RELATED_INFO'] = 'Account Address';

?>

related-info.js

({
/* 
*	File: ./custom/clients/base/fields/related-info/related-info.js
*	Author: Angel Magaña -- cheleguanaco@cheleguanaco.com 	 
*	Date: August 17, 2018
*
*	Description: Custom Sidecar field component to pull related 
*	Account data from child records. 
* 
*	e.g. Display Account address info on Case record
*/

    extendsFrom: 'BaseField',

    showNoData: false,
    relatedData: {},
    fields: [],

    initialize: function(options) {
        options.def.readonly = true;
        options.def.name = 'related-info';

        this._super('initialize', [options]);
        
        this.model.on('change:account_id', this.getRelatedAccount, this);
    },
	
	getRelatedAccount: function() {
        var self = this,
        	account_id = this.model.get('account_id');
        	
        if (_.isEmpty(account_id)) {
        	return;
        }
        	
        this.fields = ['billing_address_street', 'billing_address_city', 'billing_address_state', 'billing_address_postalcode', 'billing_address_country'];
        
        var relatedAccount = app.data.createBean('Accounts', {id: account_id});
        relatedAccount.fetch({
        	fields: this.fields,
        	success: function(data){
        		self.relatedData = data;
        		self.render();
        	}
        }); 
    }
})

After adding the field component, you need to reference it in the view metadata, as such:

            array(
            	'name' => 'related-info',
            	'type' => 'related-info',
            	'label' => 'LBL_RELATED_INFO',
            	'span' => 12,
            )

The above example is based off the Cases RecordView, for the default Accounts/Cases relationship.