You should use this plugin   to add snippets   (otherwise you should create child theme  and put code to  functions.php )

Following plugins supported: Checkout Add-ons, PDF Product Vouchers, Woocommerce Subscriptions, WooCommerce Bookings, WooCommerce Product Vendors, Local Pickup Plus, FooEvents, Tickera, Shipping Multiple Addresses, WooCommerce TM Extra Product Options

WooCommerce PDF Invoices & Packing Slips

// add Credit Note details
add_filter('woe_get_order_fields', 'woe_add_order_fields');
function woe_add_order_fields($fields) {
	$fields['credit_note_number'] = array( 'label' => 'Credit Note Number', 'colname' => 'Credit Note Number', 'checked' => 1 );
	$fields['credit_note_date'] = array( 'label' => 'Credit Note Date', 'colname' => 'Credit Note Date', 'checked' => 1 );
	$fields['formatted_credit_note_number'] = array( 'label' => 'Formatted Credit Note Number', 'colname' => 'Formatted  Credit Note Number', 'checked' => 1 );
	return $fields;
}
add_filter('woe_get_order_value_credit_note_number', 'woe_get_credit_note_field', 10, 3);
add_filter('woe_get_order_value_credit_note_date', 'woe_get_credit_note_field', 10, 3);
add_filter('woe_get_order_value_formatted_credit_note_number', 'woe_get_credit_note_field', 10, 3);
function woe_get_credit_note_field($value,$order, $field) {
	 $refunds = $order->get_refunds();
 	 if ( !empty( $refunds ) )  // take 1st!
		$value = get_post_meta( $refunds[0]->id, '_wcpdf_'.$field, true);
	return $value;
}

WooCommerce Checkout Add-ons

// "Checkout Add-ons" plugin
class WOE_Checkout_Addons_Mod {
	var $fields = array('Student Name','Student Grade Lavel','Teacher Name');// edit this line!!
	function __construct() {
		add_filter('woe_get_order_fields', array($this,'add_order_fields') );
		add_action('woe_order_export_started', array($this,'get_fee_details') );
		add_filter('woe_fetch_order_row', array($this,'fill_new_columns'), 10, 2);
	}
	
	function add_order_fields($fields) {
		foreach($this->fields as $pos=>$name) {
			$fields['fee_addon_'.$pos] = array('segment'=>'other','label'=>$name, 'colname'=>$name,'checked'=>1);
		}	
		return $fields;
	}
	
	function get_fee_details($order_id) {
		$this->fee_data = array();
		
		$order = new WC_Order($order_id);
		foreach($order->get_items("fee") as $item_id=>$item) {
			$pos = array_search($item['name'],$this->fields);
			if( $pos  !== false) {
				$item_meta = $order->get_item_meta( $item_id );
				$this->fee_data[$pos] = join(", ", $item_meta['_wc_checkout_add_on_value']); // many values?
			}
		}
		return $order_id; 
	}
	
	// add new values to row
	function fill_new_columns($row,$order_id) {
		foreach($this->fields as $pos=>$name) {
			if(isset($row['fee_addon_'.$pos]) AND isset($this->fee_data[$pos]) )
				$row['fee_addon_'.$pos] = $this->fee_data[$pos] ;
		}		
		return $row;
	}
}
new WOE_Checkout_Addons_Mod();

PDF Product Vouchers

// Export product "Vouchers"
class WOE_Product_Vouchers {
	function __construct() {
	
		// add new fields
		add_filter('woe_get_order_product_fields', function ($fields,$format) {
			$fields['voucher_number'] = array( 'label' => 'Voucher Number', 'colname' => 'Voucher Number', 'checked' => 1 );
			$fields['voucher_value'] = array( 'label' => 'Voucher Value', 'colname' => 'Voucher Value', 'checked' => 1);
			$fields['voucher_value_incl_tax'] = array( 'label' => 'Voucher Value (+Tax)', 'colname' => 'Voucher Value(+Tax)', 'checked' => 1);
			$fields['voucher_recipient_name'] = array( 'label' => 'Recipient Name', 'colname' => 'Recipient Name', 'checked' => 1 );
			$fields['voucher_message'] = array( 'label' => 'Message', 'colname' => 'Message', 'checked' => 1 );
			return $fields;
		}, 10, 2);
		
		// get voucher for item
		add_action( "woe_get_order_product_item", function ($item) {
			$this->voucher = false;
			$voucher_meta = $item->get_meta( '_voucher_id', false );
			if( $voucher_meta ) 
				$this->voucher = wc_pdf_product_vouchers_get_voucher( $voucher_meta[0]->value );
		});
		
		// just return fields 
		add_filter('woe_get_order_product_value_voucher_number', function ($value,$order, $item, $product) {
			if( $this->voucher )
				$value = $this->voucher->get_voucher_number();
			return $value;
		}, 10, 4);

		add_filter('woe_get_order_product_value_voucher_value', function ($value,$order, $item, $product) {
			if( $this->voucher )
				$value = $this->voucher->get_voucher_value();
			return $value;
		}, 10, 4);

		add_filter('woe_get_order_product_value_voucher_value_incl_tax', function ($value,$order, $item, $product) {
			if( $this->voucher )
				$value = $this->voucher->get_voucher_value_incl_tax();
			return $value;
		}, 10, 4);

		add_filter('woe_get_order_product_value_voucher_recipient_name', function ($value,$order, $item, $product) {
			if( $this->voucher )
				$value = $this->voucher->get_recipient_name();
			return $value;
		}, 10, 4);

		add_filter('woe_get_order_product_value_voucher_message', function ($value,$order, $item, $product) {
			if( $this->voucher )
				$value = $this->voucher->get_message();
			return $value;
		}, 10, 4);
	}	
}
new WOE_Product_Vouchers();

Woocommerce Subscriptions

// add status and dates as new columns
class WOE_Subscription_Fields_mod {
	function __construct() {
		add_filter('woe_get_order_fields', array($this,'add_order_fields') );
		add_action('woe_order_export_started', array($this,'get_subscription_details') );
		add_filter('woe_fetch_order_row', array($this,'fill_new_columns'), 10, 2);
	}
	
	function add_order_fields($fields) {
		$fields['sub_status'] = array('segment'=>'cart','label'=>'Sub. Status', 'colname'=>'Sub. Status', 'value'=>'','checked'=>1);
		$fields['sub_start_date'] = array('segment'=>'cart','label'=>'Sub. Start Date', 'colname'=>'Sub. Start Date', 'value'=>'','checked'=>1);
		$fields['sub_next_payment'] = array('segment'=>'cart','label'=>'Sub. Next Payment', 'colname'=>'Sub. Next Payment', 'value'=>'','checked'=>1);
		$fields['sub_last_order_date'] = array('segment'=>'cart','label'=>'Sub. Last Order Date', 'colname'=>'Sub. Last Order Date', 'value'=>'','checked'=>1);
		return $fields;
	}
	
	function get_subscription_details($order_id) {
		$this->sub = array();
		
		if(  WC_Order_Export_Data_Extractor::$object_type=='shop_order' ) {
			$subs = wcs_get_subscriptions_for_order($order_id, array('order_type'=>'any'));		
			$subs = array_values($subs); 
			if(!$subs)
				return $order_id;
			$sub = array_shift($subs);	
		} elseif(WC_Order_Export_Data_Extractor::$object_type=='shop_subscription' ) {
			$sub = wcs_get_subscription($order_id);
		} else {
			return $order_id;// unknow type
		}	
		$this->sub['status'] = $sub->get_status();
		//$this->sub['start_date'] = $sub->get_date_to_display("start_date"); //was 
		
		$this->sub['start_date'] = date_i18n( wc_date_format(), $sub->get_time( 'date_created', 'site' ) );
		$this->sub['next_payment'] = $sub->get_time( 'next_payment_date', 'site' ) ? date_i18n( wc_date_format(), $sub->get_time( 'next_payment_date', 'site' ) ) : '-';
		$this->sub['last_order_date'] = date_i18n( wc_date_format(), $sub->get_time( 'last_order_date_created', 'site' ) );
		return $order_id;
	}
	
	// add new values to row
	function fill_new_columns($row,$order_id) {
		foreach($this->sub as $k=>$v)
			if(isset($row['sub_'.$k]))
				$row['sub_'.$k] = $v;
		return $row;
	}
}
new WOE_Subscription_Fields_mod();

WooCommerce Bookings

class WOE_Bookings{
	function __construct() {
		add_filter('woe_get_order_product_fields',array($this,'add_product_fields') );
		add_filter('woe_get_order_product_item',array($this,'fetch_booking') );
		
		add_filter('woe_get_order_product_value_booking_status', array($this,'get_booking_field_status'), 10, 4 );
		add_filter('woe_get_order_product_value_booking_start_date', array($this,'get_booking_field_start_date'), 10, 4 );
		add_filter('woe_get_order_product_value_booking_start_time', array($this,'get_booking_field_start_time'), 10, 4 );
		add_filter('woe_get_order_product_value_booking_end_date', array($this,'get_booking_field_end_date'), 10, 4 );
		add_filter('woe_get_order_product_value_booking_end_time', array($this,'get_booking_field_end_time'), 10, 4 );
	}	
	
	function add_product_fields($fields) {
		$fields['booking_status'] = array('label'=>'Booking Status','colname'=>'Booking Status','checked'=>1,'segment'=>'cart');
		$fields['booking_start_date'] = array('label'=>'Booking Start Date','colname'=>'Booking Start Date','checked'=>1,'segment'=>'cart');
		$fields['booking_start_time'] = array('label'=>'Booking Start Time','colname'=>'Booking Start Time','checked'=>1,'segment'=>'cart');
		$fields['booking_end_date'] = array('label'=>'Booking End Date','colname'=>'Booking End Date','checked'=>1,'segment'=>'cart');
		$fields['booking_end_time'] = array('label'=>'Booking End Time','colname'=>'Booking End Time','checked'=>1,'segment'=>'cart');
		return $fields;
	}
	
	// booking for item 
	function fetch_booking($item) {
		global $wpdb;
		$this->booking = false;
		$booking_id = $wpdb->get_var( "SELECT post_id FROM {$wpdb->postmeta} WHERE meta_key= '_booking_order_item_id' AND meta_value=" . intval( $item->get_id() ) );
		if( $booking_id ) {
			$this->booking =  new WC_Booking($booking_id);
		}
		return $item;
	}
	
	function get_booking_field_status($value,$order, $item, $product) {
		return $this->booking ? $this->booking->get_status() : $value;
	}		
	function get_booking_field_start_date($value,$order, $item, $product) {
		return $this->booking ? date_i18n( wc_date_format(), $this->booking->start) : $value;
	}		
	function get_booking_field_start_time($value,$order, $item, $product) {
		return $this->booking ? date_i18n( wc_time_format(), $this->booking->start) : $value;
	}		
	function get_booking_field_end_date($value,$order, $item, $product) {
		return $this->booking ? date_i18n( wc_date_format(), $this->booking->end) : $value;
	}		
	function get_booking_field_end_time($value,$order, $item, $product) {
		return $this->booking ? date_i18n( wc_time_format(), $this->booking->end) : $value;
	}		
}	
new WOE_Bookings();

WooCommerce Product Vendors

 // add product fields "Vendor Email" and  "Vendor Name"
add_filter('woe_get_order_product_fields', function ($fields,$format) {
 $fields['vendor_email'] = array( 'label' => 'Vendor email', 'colname' => 'Vendor email', 'checked' => 1 );
 $fields['vendor_name'] = array( 'label' => 'Vendor email', 'colname' => 'Vendor email', 'checked' => 1 );
 return $fields;
}, 10, 2);

add_filter('woe_get_order_product_value_vendor_email', function ($value,$order, $item, $product,$itemmeta) {
 $vendor = WC_Product_Vendors_Utils::is_vendor_product( $item['product_id'] );
 if ( $vendor AND !empty( $vendor[0] ) ) {
  $vendor_data = WC_Product_Vendors_Utils::get_vendor_data_by_id($vendor[0]->term_id);
  if ( ! empty( $vendor_data ) ) 
   $value = $vendor_data['email'];
 }
 return $value;
}, 10, 5);

add_filter('woe_get_order_product_value_vendor_name', function ($value,$order, $item, $product,$itemmeta) {
 $vendor = WC_Product_Vendors_Utils::is_vendor_product( $item['product_id'] );
 if ( $vendor AND !empty( $vendor[0] ) ) {
  $vendor_data = WC_Product_Vendors_Utils::get_vendor_data_by_id($vendor[0]->term_id);
  if ( ! empty( $vendor_data ) ) 
   $value = $vendor_data['name'];
 }
 return $value;
}, 10, 5);

Local Pickup Plus

 // one location per order
class Woe_Pickup_Location_Fields_to_Order{
	var $shipping_info;
	
	function __construct() {
		add_filter('woe_get_order_fields', array($this,'add_shipping_fields') );
		add_filter('woe_order_export_started',array($this,'fetch_order_shipping'), 10, 1);
	}	
	
	function add_shipping_fields($fields) {
		$names = array("_pickup_location_id","_pickup_location_name","_pickup_location_address","_pickup_location_phone","_pickup_date","_pickup_items");
		foreach($names as $f) {
			$l = ucwords(trim(str_replace("_"," ",$f)));
			$fields[$f] = array('label'=>$l,'checked' => 1, 'colname'=>$l);
			add_filter('woe_get_order_value_'.$f, array($this,'get_shipping_value'), 10, 3 );
		}	
		return $fields;
	}
	
	function fetch_order_shipping($order_id) {
		//reset values
		$this->shipping_info = array();
		
		//take 1st ?
		$order = new WC_Order($order_id);
		foreach($order->get_items('shipping') as $shipping) {
			foreach($shipping->get_meta_data() as $meta) {
				$this->shipping_info[$meta->key] = $meta->value;
			}	
			break;
		}
		
		// convert some values
		if( is_array($this->shipping_info['_pickup_location_address']) ) {
			// MODIFY it?
			$_parts = array(
				$this->shipping_info['_pickup_location_address']['address_1'],
				$this->shipping_info['_pickup_location_address']['address_2'],
				$this->shipping_info['_pickup_location_address']['city'],
				$this->shipping_info['_pickup_location_address']['postcode'],
				$this->shipping_info['_pickup_location_address']['state'],
				$this->shipping_info['_pickup_location_address']['country'],
			);
			$this->shipping_info['_pickup_location_address'] = join(", ", array_filter($_parts));
		}	
		if( is_array($this->shipping_info['_pickup_items']) ){
			$items = $order->get_items('line_item');
			$item_names = array();
			foreach($this->shipping_info['_pickup_items'] as $id) {
				if(isset($items[$id]))
					$item_names[] = $items[$id]['name'] . ' x ' . $items[$id]['name'];
			}	
			$this->shipping_info['_pickup_items'] = join(",", $item_names);
		}	
		
		return $order_id;
	}
	
	function get_shipping_value($value,$order,$field) {
		if( isset($this->shipping_info[$field]) ) {
			$value = $this->shipping_info[$field];
		}
		return $value;
	}
	
}
new Woe_Pickup_Location_Fields_to_Order();

FooEvents For WooCommerce

You should EDIT  and TWEAK code , see comments!

class WOE_FooTickets_As_Products {
	var $fields = array("TicketType"=>"Ticket Type","Status"=>"Ticket Status","AttendeeName"=>"Attendee First Name","AttendeeLastName"=>"Attendee Last Name",
					"AttendeeEmail"=>"Attendee Email","AttendeeTelephone"=>"Attendee Phone","AttendeeCompany"=>"Attendee Company","AttendeeDesignation"=>"Attendee Designation",
					"PurchaserFirstName"=>"Purchaser First Name","PurchaserLastName"=>"Purchaser Last Name","PurchaserEmail"=>"Purchaser Email"); 
	var $custom_fields = array("nom_participant"=>"Nom participant","club_participant"=>"club Participant"); // ADD as "field"=>"label"
	function __construct() {
		add_filter('woe_get_order_product_fields', function ($fields) {
			foreach($this->fields as $field=>$label)
				$fields['ticket_standard_'.$field] = array( 'label' => $label, 'colname' => $label, 'checked' => 1 );
			foreach($this->custom_fields as $field=>$label)
				$fields['ticket_custom_'.$field] = array( 'label' => $label, 'colname' => $label, 'checked' => 1 );
			return $fields;
		});
		add_filter('woe_fetch_order_products',function ($products,$order,$labels, $format, $static_vals) {
			$tickets_set = get_post_meta($order->id, "WooCommerceEventsOrderTickets", true);
			$this->line_id = 1;
			$results = array();
			$pos = 0;
			$products = array_values($products);
			foreach ( $order->get_items('line_item') as $item_id=>$item ) {
				$found_ticket = false;
				// seek for assigned tickets
				$product_data = $products[$pos++]; // take already extracted data for product!
				foreach($tickets_set as $tickets) {
					foreach($tickets as $ticket) {
						// found assigned tickets??
						if(	$item['product_id'] AND !$item['variation_id'] AND ($ticket['WooCommerceEventsProductID'] == $item['product_id'])  
                                                  OR $item['variation_id'] AND ($ticket['WooCommerceEventsVariationID'] == $item['variation_id'])  ) {
							$this->add_ticket($results, $ticket,$labels,$product_data);
							$found_ticket = true;
						}	
					}
				}
				if( ! $found_ticket ) // not ticket, stay unchanaged!
					$results[] = $product_data;
			}
			return $results;
		},10,5);
	}// end __construct
	
	function add_ticket(&$results, $ticket,$labels,$product_data) {
		$row = array();
		foreach ( $labels as $field => $label ) {
			if ( $field == 'line_id' ) {
				$row[ $field ] = $this->line_id++;
			} elseif ( preg_match('#ticket_standard_(.+)$#',$field,$m) ) { // FooEvents field
				$row[ $field ] = $ticket["WooCommerceEvents".$m[1]];
			} elseif ( preg_match('#ticket_custom_(.+)$#',$field,$m) ) { // FooEvents custom field 
				$row[ $field ] = $ticket["WooCommerceEventsCustomAttendeeFields"]["fooevents_custom_".$m[1]];
			} elseif ( isset( $product_data[$field]) ) { // Item field ?
				$row[ $field ] = $product_data[$field];
			} else
				$row[ $field ] = '';
		}
		$results[] = $row;
	}
}
new WOE_FooTickets_As_Products();

Tickera

add_filter('woe_get_order_product_fields', 'woe_add_ticket_fields');
function woe_add_ticket_fields($fields) {
	$fields['event_name'] = array('label'=>'Event Name','colname'=>'Event Name','checked'=>1);
	$fields['event_start_at'] = array('label'=>'Event Start','colname'=>'Event Start','checked'=>1);
	$fields['event_end_at'] = array('label'=>'Event End','colname'=>'Event End','checked'=>1);
	$fields['event_location'] = array('label'=>'Event Location','colname'=>'Event Location','checked'=>1);
	$fields['ticket_type'] = array('label'=>'Ticket Type','colname'=>'Ticket Type','checked'=>1);
	$fields['ticket_owner'] = array('label'=>'Ticket Owner Name','colname'=>'Ticket Owner Name','checked'=>1);
	$fields['ticket_email'] = array('label'=>'Ticket Owner Email','colname'=>'Ticket Owner Email','checked'=>1);
	$fields['ticket_code'] = array('label'=>'Ticket Code','colname'=>'Ticket Code','checked'=>1);
	return $fields;
}

add_filter('woe_fetch_order_products', 'woe_fill_ticket_fields',10,5);
function woe_fill_ticket_fields($data, $order, $labels, $format, $static_vals ) {
	$args = array(
		'posts_per_page' => -1,
		'orderby' => 'post_date',
		'order' => 'ASC',
		'post_type' => 'tc_tickets_instances',
		'post_parent' => $order->get_id(),
	);
	$tickets = get_posts($args);
	$data = array_values($data); //we dont need item ids here!
	foreach($tickets  as $pos=>$ticket) {
		// copy data from first line
		if(!isset($data[$pos]))
			$data[$pos] = $data[0];
		//fill ticket data	
		$ticket_type_id = get_post_meta($ticket->ID, 'ticket_type_id', true);
		if( $ticket_type_id )  {
			$ticket_type = new TC_Ticket($ticket_type_id);
			if( $ticket_type  ) {
				$event_id = $ticket_type->get_ticket_event();
				$event = get_post($event_id, ARRAY_A);
				$data[$pos]['event_name']	=  $event['post_title'];
				$data[$pos]['event_start_at']	=  get_post_meta( $event_id , 'event_date_time', true);
				$data[$pos]['event_end_at']	=  get_post_meta( $event_id , 'event_end_date_time', true);
				$data[$pos]['event_location']	=  get_post_meta( $event_id , 'event_location', true);
				$data[$pos]['ticket_type']	=  $ticket_type->details->post_title;
				$data[$pos]['ticket_owner']	=  get_post_meta($ticket->ID, 'first_name', true) ." " .get_post_meta($ticket->ID, 'last_name', true); 
				$data[$pos]['ticket_email']	=  get_post_meta($ticket->ID, 'owner_email', true); 
				$data[$pos]['ticket_code']	=  get_post_meta($ticket->ID, 'ticket_code', true);
			}	
		}	
	}
	return $data;
}

Shipping Multiple Addresses

//this code adds shipping information for each product
class WOE_add_product_shipping{
	var $items_shipping;
	
	function __construct() {
		add_filter('woe_get_order_product_fields', array($this,'add_shipping_fields'), 10, 2);
		add_filter('woe_order_export_started',array($this,'fetch_product_shipping'), 10, 1);
		add_filter('woe_fetch_order_product',array($this,'fill_product_shipping'), 10, 5);
	}	
	
	function add_shipping_fields($fields,$format) {
		$names = array('first_name','last_name','full_name','company','country','address_1','address_2','city','state','postcode');
		foreach($names as $f) {
			$fields['shipping_'.$f] = array('label'=>"Product Shipping ".$f,'checked' => 1, 'colname'=>"Product Shipping ".$f);
		}	
		return $fields;
	}
	
	function fetch_product_shipping($order_id) {
		//reset values
		$this->items_shipping = array();
		
		$shipping_packages = get_post_meta($order_id, '_wcms_packages', true );
		foreach($shipping_packages  as $pack) {
			$addr = $pack['destination'];
			foreach($pack["contents"] as $item) {
				$key = $item['product_id']."-".$item['variation_id'];
				$addr['full_name'] = trim($addr['first_name'] . " " . $addr['last_name']); // new field
				$this->items_shipping[$key] = $addr;
			}
		}
		return $order_id;
	}
	
	function fill_product_shipping($row, $order, $item, $product, $item_meta) { 
		$key = $item['product_id']."-".$item['variation_id'];
		if( isset($this->items_shipping[$key]) ) {
			foreach($this->items_shipping[$key] as $k=>$v) {
				$k = 'shipping_'.$k;
				if( isset($row[$k]) )
					$row[$k] = $v; 
			}
		}
		return $row;
	}
}	
new WOE_add_product_shipping();

WooCommerce TM Extra Product Options

You should EDIT  and TWEAK code , see comments!

class WOE_add_extra_fields {
	var $tm_fields = array('Age','Sex'); // EDIT list here 
	function __construct() {
		add_filter('woe_get_order_product_fields',array($this,'add_product_fields') );
		add_filter('woe_get_order_product_item_meta', array($this,'fill_tm_fields') );
	}	
	
	function add_product_fields($fields) {
		foreach($this->tm_fields as $pos=>$name) {
			$fields['tm_field_'.$pos] = array('label'=>$name,'colname'=>$name,'checked'=>1);
		}	
		return $fields;
	}
	
	//TWEAK  output for each field 
	function format_line($tm_field) {
		return $tm_field['value'];  // can use $tm_field['name'], $tm_field['price'] , $tm_field['quantity'] 
	}	
	
	function fill_tm_fields($item_meta) {
		// Gather TM values to array
		$product_fields = array();
		$product_fields[] = array();
		
		//Cart Fees
		if( isset($item_meta["_tmcartfee_data"])   AND  is_array($tmfields = maybe_unserialize($item_meta["_tmcartfee_data"][0]))  ) {
			foreach($tmfields[0] as $tm_field) {
				$name = $tm_field['name'];
				if( !isset($product_fields[$name]) ) 
					$product_fields[$name] = array();
				$product_fields[$name][] = $this->format_line($tm_field); 
			}
		}
		
		//Cart Items
		if( isset($item_meta["_tmcartepo_data"])   AND  is_array($tmfields = maybe_unserialize($item_meta["_tmcartepo_data"][0]))  ) {
			foreach($tmfields as $tm_field) {
				$name = $tm_field['name'];
				if( !isset($product_fields[$name]) ) 
					$product_fields[$name] = array();
				$product_fields[$name][] = $this->format_line($tm_field); 
			}
		}
		
		//make list 
		foreach($product_fields as $name=>$values)
			$product_fields[ $name ] = join("\n", $values);
		
		// add to item meta 
		foreach($this->tm_fields as $pos=>$name) {
			 // it must be array !
			$item_meta['tm_field_'.$pos] = array( isset($product_fields[$name]) ? $product_fields[$name] : "" );
		}	
		return $item_meta;
	}
}	
new WOE_add_extra_fields();