Magento 2 Custom UI grid form.php validate upload file extension

Question

I want to check the upload file extension in form.php, I have three upload file options I want to check the upload file is pdf or not. Thanks in advance. my form.php file is

namespace Vendor\Extension\Block\Adminhtml\Blog\Edit;

use Magento\Backend\Block\Template\Context;
use Magento\Framework\Registry;
use Magento\Framework\Data\FormFactory;
use Vendor\Extension\Block\Adminhtml\Status;


class Form extends \Magento\Backend\Block\Widget\Form\Generic
{
    protected $_systemStore;

    public function __construct(
        Context $context,
        Registry $registry,
        FormFactory $formFactory,
        Status $options,
        array $data = []
    )
    {
        $this->options = $options;
        parent::__construct($context, $registry, $formFactory, $data);
    }

    protected function _prepareForm()
    {
        $dateFormat = $this->_localeDate->getDateFormat(\IntlDateFormatter::SHORT);
        $model = $this->_coreRegistry->registry('row_data');
        $form = $this->_formFactory->create(
            ['data' => [
                'id' => 'edit_form',
                'enctype' => 'multipart/form-data',
                'action' => $this->getData('action'),
                'method' => 'post'
            ]
            ]
        );

        $form->setHtmlIdPrefix('mtgrid_');
        if ($model->getId()) {
            $fieldset = $form->addFieldset(
                'base_fieldset',
                ['legend' => __('Edit Row Data'), 'class' => 'fieldset-wide']
            );
            $fieldset->addField('id', 'hidden', ['name' => 'id']);
        } else {
            $fieldset = $form->addFieldset(
                'base_fieldset',
                ['legend' => __('Add Row Data'), 'class' => 'fieldset-wide']
            );
        }

        $fieldset->addField(
            'prapproveno',
            'text',
            [
                'name' => 'prapproveno',
                'label' => __('Prior Approve No.'),
                'id' => 'prapproveno',
                'title' => __('Prior Approve No.'),
                'class' => '',
            ]
        );

        //$wysiwygConfig = $this->_wysiwygConfig->getConfig(['tab_id' => $this->getTabId()]);

        $fieldset->addField(
            'submitdate',
            'date',
            [
                'name' => 'submitdate',
                'label' => __('Submit Date'),
                'date_format' => $dateFormat,
                'time_format' => 'HH:mm:ss',
                'class' => 'validate-date validate-date-range date-range-custom_theme-from',
                'class' => 'required-entry',
            ]
        );
        $fieldset->addField(
            'chnlmanager',
            'text',
            [
                'name' => 'chnlmanager',
                'label' => __('Channel Maneger'),
                'id' => 'chnlmanager',
                'title' => __('Channel Manager'),
                'class' => 'required-entry',
            ]
        );
        $fieldset->addField(
            'status',
            'select',
            [
                'name' => 'status',
                'label' => __('Status'),
                'id' => 'status',
                'title' => __('Status'),
                'values' => [1=>"Enable",0=>"Disable"],
                'class' => 'status',
                'required' => true,
            ]
        );
        $fieldset->addField(
            'company',
            'select',
            [
                'name' => 'company',
                'label' => __('Company'),
                'id' => 'company',
                'title' => __('Company'),
                'values' => $this->options->getOptionArray(),
                'class' => 'required-entry',
                'required' => true,
            ]
        );
        $fieldset->addField(
            'branch',
            'text',
            [
                'name' => 'branch',
                'label' => __('Branch'),
                'id' => 'branch',
                'title' => __('Branch'),
                'class' => 'required-entry',
            ]
        );
        $fieldset->addField(
            'avpno',
            'text',
            [
                'name' => 'avpno',
                'label' => __('AVP/Reseller No.'),
                'id' => 'avpno',
                'title' => __('AVP/Reseller No.'),
                'class' => 'required-entry',
            ]
        );
        $fieldset->addField(
            'budgetfrom',
            'select',
            [
                'name' => 'budgetfrom',
                'label' => __('Budget From'),
                'id' => 'budgetfrom',
                'title' => __('Budget From'),
                'values' => $this->options->getOptionArray(),
                'class' => 'required-entry',
                'required' => true,
            ]
        );
        $fieldset->addField(
            'marketingactivity',
            'select',
            [
                'name' => 'marketingactivity',
                'label' => __('Marketing Activity'),
                'id' => 'budgetfrom',
                'title' => __('Budget From'),
                'values' => $this->options->getOptionArray(),
                'class' => 'required-entry',
                'required' => true,
            ]
        );
        $fieldset->addField(
            'description',
            'text',
            [
                'name' => 'description',
                'label' => __('Description'),
                'id' => 'description',
                'title' => __('Description'),
                'class' => 'required-entry',
            ]
        );
        $fieldset->addField(
            'file1',
            'file',
            [
                'name' => 'file1',
                'label' => __('Attachments'),
                'id' => 'file1',
                'title' => __('Attachments'),
                'note' => 'PDF format only'
            ]
        );
        $fieldset->addField(
            'file2',
            'file',
            [
                'name' => 'file2',
                'id' => 'file2',
                'note' => 'PDF format only'
            ]
        );
        $fieldset->addField(
            'file3',
            'file',
            [
                'name' => 'file3',
                'id' => 'file3',
                'note' => 'PDF format only'
            ]
        );
        $form->setValues($model->getData());
        $form->setUseContainer(true);
        $this->setForm($form);
        return parent::_prepareForm();
    }
} 

Answer 1

You can validate the file extension in the controller before saving the form.

app/code/Vendor/Extension/Controller/Adminhtml/Blog/Save.php

Check the below code.

<?php

namespace Vendor\Extension\Controller\Adminhtml\Blog;

use Magento\Backend\App\Action;
use Magento\Framework\App\Filesystem\DirectoryList;
use Magento\Framework\Exception\LocalizedException;
use Magento\Framework\Filesystem;
use Magento\MediaStorage\Model\File\UploaderFactory;

class Save extends Action
{
    protected $fileSystem;

    protected $uploaderFactory;

    protected $allowedExtensions = ['csv'];

    protected $fileId = 'file';

    public function __construct(
        Action\Context $context,
        Filesystem $fileSystem,
        UploaderFactory $uploaderFactory
    ) {
        $this->fileSystem = $fileSystem;
        $this->uploaderFactory = $uploaderFactory;
        parent::__construct($context);
    }

    public function execute()
    {
        $destinationPath = $this->getDestinationPath();

        try {
            $uploader = $this->uploaderFactory->create(['fileId' => $this->fileId])
                ->setAllowCreateFolders(true)
                ->setAllowedExtensions($this->allowedExtensions)
                ->addValidateCallback('validate', $this, 'validateFile');
            if (!$uploader->save($destinationPath)) {
                throw new LocalizedException(
                    __('File cannot be saved to path: $1', $destinationPath)
                );
            }
        } catch (\Exception $e) {
            $this->messageManager->addError(
                __($e->getMessage())
            );
        }
    }

    public function validateFile($filePath)
    {
        // @todo
        // your custom validation code here
    }

    public function getDestinationPath()
    {
        return $this->fileSystem
            ->getDirectoryWrite(DirectoryList::TMP)
            ->getAbsolutePath('/');
    }
}