Модель данных - Как определить два класса модели и метод свойства с отношением 1 ко многим между ними?

Question

Этот вопрос двоякий.

1)

В моем коде существуют две модели с отношением 1-ко-многим (1 пользователь имеет много элементов действий).Как настроить это соединение в классе PHP?

2)

Одной из моделей, actionitem, нужна функция свойства для получения полного имени (Last, First)из actionitem, составленного из 4 типов user s, этот метод свойства должен действительно происходить (зависеть от) user, определяемого идентификатором.

Как мне достичь этой цели?

<?php
    namespace data\model;

    class actionitem {
        //Users
        public $assignorid;          
        public $ownerid;      
        public $altownerid;
        public $approverid;
        //Additional Attributes
        public $actionitemtitle;
        public $actionitemstatement; 

        //Property Function 1
        //How do I create the property function for $assignorid?
        public function getAssignor(){
             return ??
        }
    }

Проблема в том, что у меня есть функция свойства, указанная в моем user классе

<?php
    namespace data\model;

    class user {
        public $userid;
        public $userlastname;
        public $userfirstname;

        //Property Function 2
        public function getUserLastFirst(){
             return trim($this->userlastname, ', ', $this->userfirstname);
        }
    }

Mapper class

<?php
    class actionitems {

        private $db = null;

        public function __construct(PDO $db){
            $this->db = $db;
        }

        protected function __populateFromCollection($results){
            $return = array();

            foreach($results as $result){
                $return = $this->mapFromArray($result);
            }

            return $return;
        }

        public function mapFromArray($array, \data\model\actionitem $actionitem = null){
            if (is_null($actionitem)) $actiontiem = new actionitem();
            //Mapping code
            if (is_null($array['assignor.lastname'])) $actionitem->assignorlastname = $array['assignor.lastname'];
            if (is_null($array['assignor.firstname'])) $actionitem->assignorfirstname = $array['assignor.firstname'];
            if (is_null($array['owner.lastname'])) $actionitem->ownerlastname = $array['owner.lastname'];
            if (is_null($array['owner.firstname'])) $actionitem->ownerfirstname = $array['owner.firstname'];
            if (is_null($array['altowner.lastname'])) $actionitem->altownerlastname = $array['altowner.lastname'];
            if (is_null($array['altowner.firstname'])) $actionitem->altownerfirstname = $array['altowner.firstname'];
            if (is_null($array['approver.lastname'])) $actionitem->altownerlastname = $array['approver.lastname'];
            if (is_null($array['approver.firstname'])) $actionitem->approverfirstname = $array['approver.firstname'];

        }

        public function get($id){

        }

        public function getAll($params = [])
        {
            $whereStrings = $whereParams = array();

            if (isset($params['Keyword'])){

                $searchCols = 
                   [
                    'assignor.lastname',
                    'assignor.firstname',
                    'owner.lastname',
                    'owner.firstname',
                    'altowner.lastname',
                    'altowner.firstname',
                    'approver.lastname',
                    'approver.firstname',
                    'actionitemtitle',
                    'criticality',
                    'actionitemstatement',
                    'closurecriteria',
                    'closurestatement',
                    'rejectionjustification',
                    'ownernotes',
                    'approvercomments',
                    'notes'
                    ];


                foreach ($searchCols as $col){
                    $whereStrings[] = "$col like ?";
                    $whereParams[] = $params['Keyword'];
                }
            }    

            $sql = "select
                        assignor.lastname  AS assignorlastname,
                        assignor.firstname AS assignorfirstname,
                        owner.lastname  AS ownerlastname,
                        owner.firstname AS ownerfirstname,
                        altowner.lastname  AS altownerlastname,
                        altowner.firstname AS altownerfirstname,
                        approver.lastname  AS approverlastname,
                        approver.firstname AS approverfistname,
                        a.*
                    from actionitems a
                    inner join users assignor
                        ON a.assignorid = assignor.userid
                    inner join users owner
                        ON a.approverid = owner.userid
                    inner join users altowner
                        ON a.altownerid = altowner.userid
                    inner join users approver
                        ON a.approverid = approver.userid";

            if (!empty($whereStrings)){
                $sql .= " where " . implode(' AND ' . $whereStrings);
            }
            if (isset($params['limit'])){
                $sql .= " limit " . intval($params['limit']);
            }

            $statement  = $this->db->prepare($sql);
            $statement->execute($whereParams);
            $resuls = $statement->fetchAll();
            return $this->__populateFromCollection($results);
        }
    }