Magento 2 Import Export – Import Custom CSV to Custom Table

note: I get crystal clear explanation of custom import option from this link

Please first download the whole zip file from this github link then change the module name as per your requirement. Just alter the two files is enough to import your custom CSV to custom table.

step1: alter app/code/vendor/module_name/etc/import.xml from your download github folder.

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_ImportExport:etc/import.xsd">
    <entity name="chennai_event" label="Chennai Event" model="Gworks\Chennaievent\Model\Import\CustomerGroup" behaviorModel="Magento\ImportExport\Model\Source\Import\Behavior\Basic" />
</config>

step2: then you should need to create model class as per mention in the above import.xml

app/code/vendor/module_name/Model/Import/CustomerGroup.php

<?php
namespace Gworks\Chennaievent\Model\Import;

use Gworks\Chennaievent\Model\Import\CustomerGroup\RowValidatorInterface as ValidatorInterface;
use Magento\ImportExport\Model\Import\ErrorProcessing\ProcessingErrorAggregatorInterface;
use Magento\Framework\App\ResourceConnection;

class CustomerGroup extends \Magento\ImportExport\Model\Import\Entity\AbstractEntity
{

    const ID = 'id';
    const EVENTNAME = 'event_name';
    const IMGURL = 'event_imgurl';
    const BANNERIMGURL = 'event_bannerimgurl';
    const DESC = 'event_description';
    const LDESC = 'event_longdescription';
    const PLACE = 'event_place';
    const DATE = 'event_date';
    const GIFT = 'event_suggestgift';
    const TYPE = 'type';

    const TABLE_Entity = 'chennai_event';

    /**
     * Validation failure message template definitions
     *
     * @var array
     */
    protected $_messageTemplates = [
    ValidatorInterface::ERROR_TITLE_IS_EMPTY => 'TITLE is empty',
    ];

     protected $_permanentAttributes = [self::ID];
    /**
     * If we should check column names
     *
     * @var bool
     */
    protected $needColumnCheck = true;
    protected $groupFactory;
    /**
     * Valid column names
     *
     * @array
     */
    protected $validColumnNames = [
    self::ID,
    self::EVENTNAME,
    self::IMGURL,
    self::BANNERIMGURL,
    self::DESC,
    self::LDESC,
    self::PLACE,
    self::DATE,
    self::GIFT,
    self::TYPE,
    ];

    /**
     * Need to log in import history
     *
     * @var bool
     */
    protected $logInHistory = true;

    protected $_validators = [];


    /**
     * @var \Magento\Framework\Stdlib\DateTime\DateTime
     */
    protected $_connection;
    protected $_resource;

    /**
     * @SuppressWarnings(PHPMD.CouplingBetweenObjects)
     */
    public function __construct(
    \Magento\Framework\Json\Helper\Data $jsonHelper,
    \Magento\ImportExport\Helper\Data $importExportData,
    \Magento\ImportExport\Model\ResourceModel\Import\Data $importData,
    \Magento\Framework\App\ResourceConnection $resource,
    \Magento\ImportExport\Model\ResourceModel\Helper $resourceHelper,
    \Magento\Framework\Stdlib\StringUtils $string,
    ProcessingErrorAggregatorInterface $errorAggregator,
    \Magento\Customer\Model\GroupFactory $groupFactory
    ) {
    $this->jsonHelper = $jsonHelper;
    $this->_importExportData = $importExportData;
    $this->_resourceHelper = $resourceHelper;
    $this->_dataSourceModel = $importData;
    $this->_resource = $resource;
    $this->_connection = $resource->getConnection(\Magento\Framework\App\ResourceConnection::DEFAULT_CONNECTION);
    $this->errorAggregator = $errorAggregator;
    $this->groupFactory = $groupFactory;
    }
    public function getValidColumnNames()
    {
    return $this->validColumnNames;
    }

    /**
     * Entity type code getter.
     *
     * @return string
     */
    public function getEntityTypeCode()
    {
    return 'chennai_event';
    }

    /**
     * Row validation.
     *
     * @param array $rowData
     * @param int $rowNum
     * @return bool
     */
    public function validateRow(array $rowData, $rowNum)
    {

    $title = false;

    if (isset($this->_validatedRows[$rowNum])) {
        return !$this->getErrorAggregator()->isRowInvalid($rowNum);
    }

    $this->_validatedRows[$rowNum] = true;
    // BEHAVIOR_DELETE use specific validation logic
       // if (\Magento\ImportExport\Model\Import::BEHAVIOR_DELETE == $this->getBehavior()) {
        if (!isset($rowData[self::ID]) || empty($rowData[self::ID])) {
            $this->addRowError(ValidatorInterface::ERROR_TITLE_IS_EMPTY, $rowNum);
            return false;
        }

    return !$this->getErrorAggregator()->isRowInvalid($rowNum);
    }


    /**
     * Create Advanced price data from raw data.
     *
     * @throws \Exception
     * @return bool Result of operation.
     */
    protected function _importData()
    {
    if (\Magento\ImportExport\Model\Import::BEHAVIOR_DELETE == $this->getBehavior()) {
        $this->deleteEntity();
    } elseif (\Magento\ImportExport\Model\Import::BEHAVIOR_REPLACE == $this->getBehavior()) {
        $this->replaceEntity();
    } elseif (\Magento\ImportExport\Model\Import::BEHAVIOR_APPEND == $this->getBehavior()) {
        $this->saveEntity();
    }

    return true;
    }
    /**
     * Save newsletter subscriber
     *
     * @return $this
     */
    public function saveEntity()
    {
    $this->saveAndReplaceEntity();
    return $this;
    }
    /**
     * Replace newsletter subscriber
     *
     * @return $this
     */
    public function replaceEntity()
    {
    $this->saveAndReplaceEntity();
    return $this;
    }
    /**
     * Deletes newsletter subscriber data from raw data.
     *
     * @return $this
     */
    public function deleteEntity()
    {
    $listTitle = [];
    while ($bunch = $this->_dataSourceModel->getNextBunch()) {
        foreach ($bunch as $rowNum => $rowData) {
            $this->validateRow($rowData, $rowNum);
            if (!$this->getErrorAggregator()->isRowInvalid($rowNum)) {
                $rowTtile = $rowData[self::ID];
                $listTitle[] = $rowTtile;
            }
            if ($this->getErrorAggregator()->hasToBeTerminated()) {
                $this->getErrorAggregator()->addRowToSkip($rowNum);
            }
        }
    }
    if ($listTitle) {
        $this->deleteEntityFinish(array_unique($listTitle),self::TABLE_Entity);
    }
    return $this;
    }
 /**
     * Save and replace newsletter subscriber
     *
     * @return $this
     * @SuppressWarnings(PHPMD.CyclomaticComplexity)
     * @SuppressWarnings(PHPMD.NPathComplexity)
     */
    protected function saveAndReplaceEntity()
    {
    $behavior = $this->getBehavior();
    $listTitle = [];
    while ($bunch = $this->_dataSourceModel->getNextBunch()) {
        $entityList = [];
        foreach ($bunch as $rowNum => $rowData) {
            if (!$this->validateRow($rowData, $rowNum)) {
                $this->addRowError(ValidatorInterface::ERROR_TITLE_IS_EMPTY, $rowNum);
                continue;
            }
            if ($this->getErrorAggregator()->hasToBeTerminated()) {
                $this->getErrorAggregator()->addRowToSkip($rowNum);
                continue;
            }

            $rowTtile= $rowData[self::ID];
            $listTitle[] = $rowTtile;
            $entityList[$rowTtile][] = [
              self::ID => $rowData[self::ID],
              self::EVENTNAME => $rowData[self::EVENTNAME],
                self::IMGURL => $rowData[self::IMGURL],
                self::BANNERIMGURL => $rowData[self::BANNERIMGURL],
                self::DESC => $rowData[self::DESC],
                self::LDESC => $rowData[self::LDESC],
                self::PLACE => $rowData[self::PLACE],
                self::DATE => $rowData[self::DATE],
                self::GIFT => $rowData[self::GIFT],
                self::TYPE => $rowData[self::TYPE],
            ];
        }
        if (\Magento\ImportExport\Model\Import::BEHAVIOR_REPLACE == $behavior) {
            if ($listTitle) {
                if ($this->deleteEntityFinish(array_unique(  $listTitle), self::TABLE_Entity)) {
                    $this->saveEntityFinish($entityList, self::TABLE_Entity);
                }
            }
        } elseif (\Magento\ImportExport\Model\Import::BEHAVIOR_APPEND == $behavior) {
            $this->saveEntityFinish($entityList, self::TABLE_Entity);
        }
    }
    return $this;
    }
    /**
     * Save product prices.
     *
     * @param array $priceData
     * @param string $table
     * @return $this
     */
    protected function saveEntityFinish(array $entityData, $table)
    {
    if ($entityData) {
        $tableName = $this->_connection->getTableName($table);
        $entityIn = [];
        foreach ($entityData as $id => $entityRows) {
                foreach ($entityRows as $row) {
                    $entityIn[] = $row;
                }
        }
        if ($entityIn) {
            $this->_connection->insertOnDuplicate($tableName, $entityIn,[
                self::ID,
                self::EVENTNAME,
                self::IMGURL,
                self::BANNERIMGURL,
                self::DESC,
                self::LDESC,
                self::PLACE,
                self::DATE,
                self::GIFT,
                self::TYPE
        ]);
        }
    }
    return $this;
    }
    protected function deleteEntityFinish(array $listTitle, $table)
    {
    if ($table && $listTitle) {
            try {
                $this->countItemsDeleted += $this->_connection->delete(
                    $this->_connection->getTableName($table),
                    $this->_connection->quoteInto('customer_group_code IN (?)', $listTitle)
                );
                return true;
            } catch (\Exception $e) {
                return false;
            }

    } else {
        return false;
    }
    }
}

My table structure

thats it, for any clarity related to this answer please mention in comment.

@Atish Goshwami answer also correct, Why am I update? because with my way I could achieve result within twenty minutes its simple way to done this.