namespace CompanyModuleModelResourceModelCustomGrid;

    use MagentoFrameworkApiSearchSearchResultInterface;
    use MagentoFrameworkSearchAggregationInterface;
    use CompanyModuleModelResourceModelCustomCollection as CustomCollection;


    class MyCollection extends CustomCollection implements SearchResultInterface{

         /**
         * @var AggregationInterface
         */
        protected $aggregations;
         protected $request;

        public function __construct(
            MagentoFrameworkDataCollectionEntityFactoryInterface $entityFactory,
            PsrLogLoggerInterface $logger,
            MagentoFrameworkDataCollectionDbFetchStrategyInterface $fetchStrategy,
            MagentoFrameworkEventManagerInterface $eventManager,
            MagentoStoreModelStoreManagerInterface $storeManager,
            MagentoFrameworkAppRequestInterface $request,
            $mainTable,
            $eventPrefix,
            $eventObject,
            $resourceModel,
            $model = 'MagentoFrameworkViewElementUiComponentDataProviderDocument',
            $connection = null,
            MagentoFrameworkModelResourceModelDbAbstractDb $resource = null

        ) {
            $this->addFilterToMap('customer_name','firstname');
            parent::__construct(
                $entityFactory,
                $logger,
                $fetchStrategy,
                $eventManager,
                $storeManager,
                $connection,
                $resource
            );
            $this->request = $request;
            $this->_eventPrefix = $eventPrefix;
            $this->_eventObject = $eventObject;
            $this->_init($model, $resourceModel);
            $this->setMainTable($mainTable);
        }

        /**
         * @return AggregationInterface
         */
        public function getAggregations()
        {
            return $this->aggregations;
        }

        /**
         * @param AggregationInterface $aggregations
         * @return $this
         */
        public function setAggregations($aggregations)
        {
            $this->aggregations = $aggregations;
        }


        /**
         * Retrieve all ids for collection
         * Backward compatibility with EAV collection
         *
         * @param int $limit
         * @param int $offset
         * @return array
         */
        public function getAllIds($limit = null, $offset = null)
        {
            return $this->getConnection()->fetchCol($this->_getAllIdsSelect($limit, $offset), $this->_bindParams);
        }

        /**
         * Get search criteria.
         *
         * @return MagentoFrameworkApiSearchCriteriaInterface|null
         */
        public function getSearchCriteria()
        {
            return null;
        }

        /**
         * Set search criteria.
         *
         * @param MagentoFrameworkApiSearchCriteriaInterface $searchCriteria
         * @return $this
         * @SuppressWarnings(PHPMD.UnusedFormalParameter)
         */
        public function setSearchCriteria(MagentoFrameworkApiSearchCriteriaInterface $searchCriteria = null)
        {
            return $this;
        }

        /**
         * Get total count.
         *
         * @return int
         */
        public function getTotalCount()
        {
            return $this->getSize();
        }

        /**
         * Set total count.
         *
         * @param int $totalCount
         * @return $this
         * @SuppressWarnings(PHPMD.UnusedFormalParameter)
         */
        public function setTotalCount($totalCount)
        {
            return $this;
        }

        /**
         * Set items list.
         *
         * @param MagentoFrameworkApiExtensibleDataInterface[] $items
         * @return $this
         * @SuppressWarnings(PHPMD.UnusedFormalParameter)
         */
        public function setItems(array $items = null)
        {
            return $this;
        }

        protected function _renderFiltersBefore() {


            $custId = $this->getRequest()->getParam('id');

            $this->addFieldToFilter('main_table.customer_id',$custId);
            $joinTable = $this->getTable('customer_entity');
            $this->getSelect()->join($joinTable.' as customer','main_table.customer_id = customer.entity_id',
                                array('customer_name'=>"CONCAT(firstname,' ',lastname)"));

            parent::_renderFiltersBefore();
        }
}