Create a CSV Export in Wordress

This code creates a sample plugin that can export users from word press based on roles

So logically the hook is as below

add_action( 'admin_post_{action_name}', 'action_name_callback' );

and the action name need to be specified as hidden field on form in backend

<input type="hidden" name="action" value="action_name">

<?php

/*

Plugin Name: Member export

Author: Nazrul Hassan

Description: Export Users

version:1.0

*/

if ( ! defined( 'ABSPATH' ) ) exit; // Exit if accessed directly

function export_member(){

 add_menu_page('Export Member Title', 'Member Member ', 'manage_options', 'export-member', 'export_member_callback','dashicons-awards');

}

add_action('admin_menu', 'export_member');

function export_member_callback(){

?>

		<form action="<?php echo admin_url(); ?>/admin-post.php" method="post">

			  <input type="hidden" name="action" value="export_member_csv1">

		<hr>

			 <input type="submit" value="Export Users" class="button button-primary button-large">

		</form>  

<?php

}

add_action( 'admin_post_export_member_csv1', 'export_member_csv_callback' );

function export_member_csv_callback() {

	if ( ! current_user_can( 'manage_options' ) )

        return;

    $csv_filename = 'member_'.date('D-M-d-Y-H:i:s-A-e',time()).'.csv' ;

    header('Content-Type: application/csv');

    header('Content-Disposition: attachment; filename='.$csv_filename);

    header('Pragma: no-cache');

    header('Expires: 0');

    $file = fopen('php://output', 'w');

    // send the column headers

    $csvheaders = array(

    	'S.No',

    	'User ID',

    	'Email',

    	'First Name',

    	'Last Name',

    );

     fputcsv($file, $csvheaders ,',');

 		$args = array(

				'role__in'   => array('Editor') ,

			);

    $user_query = new WP_User_Query($args );

	$users 		= $user_query->get_results();

		$i=1;

	foreach ( $users as $user ) {

		$email   					= $user->data->user_email ;

		$fname   					= get_user_meta($user->id,'first_name',true); 

		$lname	 					= get_user_meta($user->id,'last_name',true);

    $csvcolumns = array(

    		$i,

			$user->data->ID, 

			$email,

			$fname,

			$lname

		) ;

    fputcsv($file,$csvcolumns);

    $i++;

	}

	exit();

}