WordPress Generate Downloadable File

generate-downloadable-file.php

/**
 * Add below code in themes functions.php OR you can add this in your plugin too.
 *
 * Here,
 * 
 * - We generate the `.json` file.
 * - We can change the file type as per requirement.
 */

/**
 * Step 1: Add Download Button
 */
add_action( 'wp_head', 'my_prefix_download_button' );
function my_prefix_download_button() {
	?>
	<a href="<?php echo esc_url( admin_url( 'admin-ajax.php?action=my_prefix_download_file' ) ); ?>" class="button button-primary" ><i class="dashicons dashicons-download"></i> <?php _e( 'Download', 'astra-theme' ); ?></a>
	<?php
}

/**
 * Step 2: Register AJAX
 *
 * Here, We generate the `.json` file.
 *
 * For other file types
 */
add_action( 'wp_ajax_my_prefix_download_file', 'my_prefix_download_file' );
add_action( 'wp_ajax_nopriv_my_prefix_download_file', 'my_prefix_download_file' );

function my_prefix_download_file() {

	// File name.
	$file_name = 'my-file-' . date( 'd-m-Y' );

	// File contents.
	$my_array = array(
		'one' => __( 'One', 'my-textdomain' ),
		'two' => __( 'Two', 'my-textdomain' ),
		'three' => __( 'Three', 'my-textdomain' ),
	);

	$file_contents = json_encode( $my_array );

	// Generate downloadable file.
	header( 'Content-Description: File Transfer' );
	header( 'Content-type: text/json' );
	header( 'Content-Disposition: attachment; filename="'.$file_name.'.json"' );
	header( 'Content-Transfer-Encoding: binary' );
	header( 'Expires: 0' );
	header( 'Cache-Control: must-revalidate' );
	header( 'Pragma: public' );

	echo $file_contents;
	exit;
}