Add a custom field to the members list CSV export in Paid Memberships Pro.

my_pmpro_members_list_csv_extra_columns.php

<?php
/*
   Add employer, title, and department columns to the members list CSV export.
   Just add this code to your functions.php or a custom plugin.

   The first function here defines the column headers and a callback function for each column.
*/
function my_pmpro_members_list_csv_extra_columns($columns)
{
	$columns["employer"] = "my_extra_column_employer";
	$columns["title"] = "my_extra_column_title";
	$columns["department"] = "my_extra_column_department";
	
	return $columns;
}
add_filter("pmpro_members_list_csv_extra_columns", "my_pmpro_members_list_csv_extra_columns", 10);

/*
  These are the callback functions which take the $user object from the CSV code (which includes an array of meta data in ->metavalues, and returns the value you want.
  I expanded the code for this first function for readability, but if you have a bunch of these, you may want to scrunch them up onto one line each.
*/
function my_extra_column_employer($user)
{
  if(!empty($user->metavalues->employer))
  {
    return $user->metavalues->employer;
  }
  else
  {
    return "";
  }
}
function my_extra_column_title($user){if(!empty($user->metavalues->title)){return $user->metavalues->title;}else{return "";}}
function my_extra_column_department($user){if(!empty($user->metavalues->department)){return $user->metavalues->department;}else{return "";}}
?>