ORO platform - how to pass collection of related entities to datagrid column template?

I have an entity with related entities in ORO platform. Built-in User entity can have many built-in Access Roles. I want to display those roles in Users datagrid using custom twig template so I can wrap them in some labels or styling.

This is my section datagrids.yaml that overrides the default users datagrid:

    users-grid:
        source:
            query:
                select:
                    - What to pass here?
                join:
                    left:
                        - { join: u.roles, alias: r }
                groupBy: u.id
        columns:
            roles:
                inline_editing:
                    enable: false
                label: 'Roles'
                type: twig
                frontend_type: html
                template: 'MyBundle:User:Property/roles.html.twig'

What do I have to do to be able to access Collection of Role object in roles.html.twig?

It's not possible to do just with the YAML configuration. Instead, you have to create a datagrid listener that will populate the roles column with the data on the "result after" event. Here is an example:

• AcmeDemoBundle/EventListener/UserRolesGridListener.php

<?php

namespace AcmeDemoBundle\EventListener;

use Oro\Bundle\DataGridBundle\Datasource\ResultRecord;
use Oro\Bundle\DataGridBundle\Event\OrmResultAfter;
use Oro\Bundle\EntityBundle\ORM\DoctrineHelper;
use Oro\Bundle\UserBundle\Entity\User;

class UserRolesGridListener
{
    /** @var DoctrineHelper */
    protected $doctrineHelper;

    /**
     * @param DoctrineHelper $doctrineHelper
     */
    public function __construct(DoctrineHelper $doctrineHelper)
    {
        $this->doctrineHelper = $doctrineHelper;
    }

    /**
     * @param OrmResultAfter $event
     */
    public function onResultAfter(OrmResultAfter $event)
    {
        $userIds = [];
        /** @var ResultRecord[] $records */
        $records = $event->getRecords();
        foreach ($records as $record) {
            $userIds[] = $record->getValue('id');
        }

        $repository = $this->doctrineHelper->getEntityRepository(User::class);
        $userRoles = $repository->createQueryBuilder('user')
            ->select('partial user.{id}, partial roles.{id, label}')
            ->indexBy('user','user.id')
            ->leftJoin('user.roles','roles')
            ->where('user.id in (:userIds)')
            ->setParameter('userIds', $userIds)
            ->getQuery()
            ->getArrayResult();
        foreach ($records as $record) {
            $id = $record->getValue('id');
            $record->addData(['roles' => $userRoles[$id]['roles']]);
        }
    }
}

• AcmeDemoBundle/Resources/config/services.yml

services:
    AcmeDemoBundle\EventListener\UserRolesGridListener:
        arguments:
            - '@oro_entity.doctrine_helper'
        tags:
            - { name: kernel.event_listener, event: oro_datagrid.orm_datasource.result.after.users-grid, method: onResultAfter }

• AcmeDemoBundle/Resources/config/oro/datagrids.yml

datagrids:
    users-grid:
        columns:
            roles:
                inline_editing:
                    enable: false
                label: 'Roles'
                type: twig
                frontend_type: html
                template: 'AcmeDemoBundle:User:Column/roles.html.twig'

• AcmeDemoBundle/Resources/views/User/Column/roles.html.twig

{% for role in record.getValue('roles') %}
  <div class="role-{{ role.id }}">{{ role.label }}</div>
{% endfor %}