fg_fillablepdfs_pdf_args.php

<?php

add_filter( 'fg_fillable_pdf_args', 'add_list_field_to_pdf', 10, 4 );

function add_list_field_to_pdf( $pdf_meta, $feed, $entry, $form ) {

	// Prepare column names for each day of the week.
	$column_names = array(
		'Sunday %d',
		'Monday %d',
		'Tuesday %d',
		'Wednesday %d',
		'Thursday %d',
		'Friday %d',
		'Saturday %d',
	);

	// Set maximum number of rows.
	$max_rows = 4;

	// Get List items.
	$list_items = rgar( $entry, 4 ); // Replace 4 with your List field ID.
	$list_items = maybe_unserialize( $list_items );

	// If there are no List items, return.
	if ( empty( $list_items ) ) {
		return $pdf_meta;
	}

	// Loop through List rows up to the maximum row count.
	for ( $i = 0; $i < ( $max_rows + 1 ); $i++ ) {

		// Get List row.
		$list_row = rgar( $list_items, $i );

		// If List row is not found, skip.
		if ( ! $list_row ) {
			continue;
		}

		// Remove array keys from List row contents.
		$list_row = array_values( $list_row );

		// Loop through each column in the row.
		foreach ( $list_row as $col => $value ) {

			// Get the PDF key for this column.
			$pdf_key = sprintf( $column_names[ $col ], ( $i + 1 ) );

			// Add value if it is not empty.
			if ( ! rgblank( $value ) ) {
				$pdf_meta['field_values'][ $pdf_key ] = $value;
			}

		}

	}

	return $pdf_meta;

}