Gravity Forms Conditional Required Fields PHP

<?php

/*  PHP for required fields
--------------------------------------------------------------------- */

add_filter("gform_validation", "my_validate_required_fields");

function my_validate_required_fields($validation_result) {


    // set up some empty arrays

    // this will be a list of the required fields, as set in the first foreach statement below
    $newly_required_fields = array();

    // This will be a comma separated list of the field IDs of the initial questions
    $initial_questions = array();

    // This will be a comma separated list of the field IDs of the followup questions.  Each item will
    // correspond with the items in the initial questions array, so they must be in the same position
    $followup_questions = array();

    // trigger responses are the answers that the question must be set to to make followup question valid.
    // These will correspond with the followup and initial questions arrays.
    $trigger_responses  = array();


    // an example with two different forms, 2 and 3.  Any other forms will skip validation
    if ( $validation_result["form"]["id"] == 2 ) {
        $initial_questions = array(11, 13, 20, 32);
        $followup_questions = array(12, 14, 21, 33);
        $trigger_responses = array('No', 'No', 'Very unlikely', 'Very unlikely');
    }
    else if ( $validation_result["form"]["id"] == 3 ) {
        $initial_questions = array(22, 28);
        $followup_questions = array(23, 29);
        $trigger_responses = array('Very unlikely', 'Very unlikely');
    }
    else {
        return $validation_result;
    }


    // loop through fields to create a list of required fields ($newly_required_fields)
    foreach( $validation_result["form"]["fields"] AS &$field ) {

        $field_value = null;

        // check if the field id is in the initial_questions array
        if ( in_array($field['id'], $initial_questions) ) {

            // get position of field id in initial_questions
            $position = array_search( $field['id'], $initial_questions );

            // get the current field value
            $field_value = rgpost("input_{$field['id']}");

            // if the current field value exists and is equal to the trigger_response
            // add the field id of the followup question to the newly_required_fields array
            // so we can loop through the fields again later and mark the followups as required.
            if ( $field_value && $field_value != '' && ($field_value == $trigger_responses[$position]) ) {
                $newly_required_fields[] = $followup_questions[$position];
            }


        } // end if field in initial questions array


    } // end first foreach fields

    // loop through fields again, and if the field ID is in newly_required_fields, set it as
    // required, and mark the field as invalid
    foreach($validation_result["form"]["fields"] AS &$field ) {
        // check that the field ID is in newly_required_fields
        if ( in_array($field['id'], $newly_required_fields) ) {
            // set field to be required
            $field['isRequired'] = 1;

            // get current value of the followup field
            $field_value = rgpost("input_{$field['id']}");

            // if the followup field value is empty, we mark the field as invalid,
            // set failed validation to true, and setup a validation message
            if (!$field_value) {
                $validation_result['is_valid'] = false;
                $field["failed_validation"] = true;
                $field["validation_message"] = 'This field is required.';
            }

        } // end if field ID is in newly_required_fields

    } // end foreach fields


    // return the updated validation_result
    return $validation_result ;
}


?>