gf-populate.php

<?php
	if ( !class_exists( 'GFForms' ) || !defined( 'WPINC' ) ) {
		return;
	}

	class BTFunds {
		
		/**
		 * Dashboard-only initialization.
		 */
		public static function admin_init() {
            // ...
		}
		
		/**
		 * Initialization.
		 */
		public static function init() {
		    // ...
			add_filter( 'gform_field_value_paymentoption', array( __CLASS__, 'populate_paymentoption' ) );
			// ...
		}
		
		public static function populate_paymentoption( $value ) {
			if ( !isset( $_POST["input_264"] ) ) {
				return;
			}

            // get selected fund options
			$funds = self::unserialize( $_POST["input_264"] );
			
			$reinvest = 0;
			$paytobank = 0;
			
			foreach ( $funds as $fund ) {
				if ( isset( $fund['selected'] ) && isset( $fund['reinvest'] ) && isset( $fund['pay_to_bank'] ) && $fund['selected'] == 'true' ) {
					if ( $fund['reinvest'] == 'true' ) {
						$reinvest++;
					}
					
					if ( $fund['pay_to_bank'] == 'true' ) {
						$paytobank++;
					}
				}
			}
			
			if ( $reinvest > 0 ) { $value = 'reinvest'; }
			if ( $paytobank > 0 ) { $value = 'paytobank'; }
			if ( $reinvest > 0 && $paytobank > 0 ) { $value = 'both'; }

			return $value;
		}

	}

	add_action( 'admin_init', array( 'BTFunds', 'admin_init' ) );
	add_action( 'init', array( 'BTFunds', 'init' ) );
	?>