ImportExport module: can't work custom file adapter in magento2?

Question

I have rewrite \Magento\ImportExport\Model\Import class with function:

 protected function _getSourceAdapter($sourceFile)
{
 return 
 \Namespace\DownloadableImport\Model\Import\Adapter::findAdapterFor(
 $sourceFile,
 $this->_filesystem->getDirectoryWrite(DirectoryList::ROOT),
 $this->getData(self::FIELD_FIELD_SEPARATOR)
 );
}
i have replce adapter 

Magento\ImportExport\Model\Import\Adapter with \Namespace\DownloadableImport\Model\Import\Adapter

but when i uploading csv and check data process it's give me error but if i replace original adapter it works fine

my custom adapter code:

namespace Namespace\DownloadableImport\Model\Import;
use Magento\Framework\Filesystem\Directory\Write;
 class Adapter 
{
/**
 * Adapter factory. Checks for availability, loads and create instance of import adapter object.
 *
 * @param string $type Adapter type ('csv', 'xml' etc.)
 * @param Write $directory
 * @param string $source
 * @param mixed $options OPTIONAL Adapter constructor options
 *
 * @return AbstractSource
 *
 * @throws \Magento\Framework\Exception\LocalizedException
 */
public static function factory($type, $directory, $source, $options = null)
{
 if (!is_string($type) || !$type) {
 throw new \Magento\Framework\Exception\LocalizedException(
 __('The adapter type must be a non-empty string.')
 );
 }
 // $adapterClass = 'Magento\ImportExport\Model\Import\Source\\' . ucfirst(strtolower($type));
 $adapterClass = 'Namespace\DownloadableImport\Model\Import\Source\\' . ucfirst(strtolower($type));
 if (!class_exists($adapterClass)) {
 throw new \Magento\Framework\Exception\LocalizedException(
 __('\'%1\' file extension is not supported', $type)
 );
 }
 $adapter = new $adapterClass($source, $directory, $options);
 if (!$adapter instanceof AbstractSource) {
 throw new \Magento\Framework\Exception\LocalizedException(
 __('Adapter must be an instance of \Magento\ImportExport\Model\Import\AbstractSource')
 );
 } 
 return $adapter;
}
/**
 * Create adapter instance for specified source file.
 *
 * @param string $source Source file path.
 * @param Write $directory
 * @param mixed $options OPTIONAL Adapter constructor options
 *
 * @return AbstractSource
 */
public static function findAdapterFor($source, $directory, $options = null)
{
 return self::factory(pathinfo($source, PATHINFO_EXTENSION), $directory, $source, $options);
}

if (!$adapter instanceof AbstractSource) { throw new \Magento\Framework\Exception\LocalizedException( __('Adapter must be an instance of \Magento\ImportExport\Model\Import\AbstractSource') ); } if i am removing this piece of code it's working fine My custom csv code:

<?php

/** * Copyright © Magento, Inc. All rights reserved. * See COPYING.txt for license details. */ namespace Namespace\DownloadableImport\Model\Import\Source;

 class Csv extends \Magento\ImportExport\Model\Import\AbstractSource
 {
 const COL_ATTR_SET="attribute_set_code";
 const VAL_COL_TYPE="downloadable";
 const VAL_ATTR_SET="Migration_Default";
 /**
 * @var \Magento\Framework\Filesystem\File\Write
 */
protected $_file;
/**
 * Delimiter.
 *
 * @var string
 */
protected $_delimiter = ',';
/**
 * @var string
 */
protected $_enclosure = '';
public function __construct(
 $file,
 \Magento\Framework\Filesystem\Directory\Read $directory,
 $delimiter = ',',
 $enclosure = '"'
) {
 register_shutdown_function([$this, 'destruct']);
 try {
 $this->_file = $directory->openFile($directory->getRelativePath($file), 'r');
 } catch (\Magento\Framework\Exception\FileSystemException $e) {
 throw new \LogicException("Unable to open file: '{$file}'");
 }
 if ($delimiter) {
 $this->_delimiter = $delimiter;
 }
 $this->_enclosure = $enclosure;
 $this->_counter = 0;
 parent::__construct($this->_getNextRow());
}
protected function _getNextRow()
{
 $parsed = $this->_file->readCsv(0, $this->_delimiter, $this->_enclosure);
 if (is_array($parsed) && count($parsed) != $this->_colQty) {
 $counter = $this->_counter;
 if($counter == 0)
 {
 $parsed[]= \Magento\CatalogImportExport\Model\Import\Product::COL_TYPE;
 $parsed[]= \Magento\CatalogImportExport\Model\Import\Product::COL_ATTR_SET;
 $parsed[]= self::COL_ATTR_SET; 
 }
 elseif($counter > 0){
 $parsed[]= self::VAL_COL_TYPE;
 $parsed[]= self::VAL_ATTR_SET;
 $parsed[]= self::VAL_ATTR_SET; 
 }
 $this->_counter = ++$counter;
 foreach ($parsed as $element) {
 if (strpos($element, "'") !== false) {
 $this->_foundWrongQuoteFlag = true;
 break;
 }
 }
 } else {
 $this->_foundWrongQuoteFlag = false;
 }
 return is_array($parsed) ? $parsed : [];
}
public function destruct()
{
 if (is_object($this->_file)) {
 $this->_file->close();
 }
}
 public function rewind()
{
 $this->_file->seek(0);
 $this->_getNextRow();
 // skip first line with the header
 parent::rewind();
}

}

• Feedlay Technologies: What error that give? can you write that.
• Rutvee Sojitra: The file "D:/Projects/xampp/htdocs/m2/var/importexport/catalog_product.csv" cannot be deleted Warning!unlink(D:/Projects/xampp/htdocs/m2/var/importexport/catalog_product.csv): Permission denied
• Feedlay Technologies: Can you write whole error log trace because above is warning and you have written unlink ?
• Rutvee Sojitra: yes this warning is occur due to custom adapter when i replace it with original one it's not giving any warning
• Feedlay Technologies: can you check header name is proper in csv file may this message is misleading as per: github.com/magento/magento2/issues/6658

Answer 1

In file

Namespace\DownloadableImport\Model\Import\Adapter

if (!$adapter instanceof AbstractSource) replace with if (!$adapter instanceof Magento\ImportExport\Model\Import\AbstractSource)