Added new experimental snippet: Nested Form Field Listener.

gp-nested-forms/gpnf-listener-field.php

@@ -0,0 +1,74 @@
+<?php
+/**
+ * Gravity Perks // Nested Forms // Nested Form Field Listener
+ *
+ * Add a form field that will listen for changes in a Nested Form field and update to pull the value of a designated
+ * child form field.
+ *
+ * # Current Limitations
+ *
+ * 1. The value will only be retrieved from the last submitted child entry in the designed Nested Form field.
+ * 2. The Listener field's value will only update on the first submission.
+ *
+ * @version  0.1
+ * @author   David Smith <[email protected]>
+ * @license  GPL-2.0+
+ * @link     http://gravitywiz.com/documentation/gravity-forms-nested-forms/
+ *
+ * Plugin Name:  GPNF Listener Field
+ * Plugin URI:   http://gravitywiz.com/documentation/gravity-forms-nested-forms/
+ * Description:  Add a form field that will listen for changes in a Nested Form field and update to pull the value of a designated child form field.
+ * Author:       Gravity Wiz
+ * Version:      0.1
+ * Author URI:   http://gravitywiz.com
+ */
+class GPNF_Listener_Field {
+
+	public function __construct( $args = array() ) {
+
+		// set our default arguments, parse against the provided arguments, and store for use throughout the class
+		$this->_args = wp_parse_args( $args, array(
+			'form_id'              => false,
+			'nested_form_field_id' => false,
+			'target_field_id'      => false,
+			'source_field_id'      => false,
+		) );
+
+		// do version check in the init to make sure if GF is going to be loaded, it is already loaded
+		add_action( 'init', array( $this, 'init' ) );
+
+	}
+
+	public function init() {
+
+		// carry on
+		add_filter( "gform_save_field_value_{$this->_args['form_id']}_{$this->_args['nested_form_field_id']}", array( $this, 'refresh_value_on_save' ), 10, 5 );
+
+	}
+
+	public function refresh_value_on_save( $value, $entry, $field, $form, $input_id ) {
+
+		$child_entry_ids = explode( ',', $value );
+		if ( empty( $child_entry_ids ) ) {
+			return $value;
+		}
+
+		$target_child_entry = GFAPI::get_entry( array_pop( $child_entry_ids ) );
+		if ( is_wp_error( $target_child_entry ) ) {
+			return $value;
+		}
+
+		$target_value = rgar( $target_child_entry, $this->_args['source_field_id'] );
+		GFAPI::update_entry_field( $entry['id'], $this->_args['target_field_id'], $target_value );
+
+		return $value;
+	}
+
+	public function is_applicable_form( $form ) {
+
+		$form_id = isset( $form['id'] ) ? $form['id'] : $form;
+
+		return empty( $this->_args['form_id'] ) || $form_id == $this->_args['form_id'];
+	}
+
+}