MyProject/app/controllers/controller_main.php

<?php
class controller_main extends Controller
{
    public function __construct()
    {
        parent::__construct();
        if(empty($_SESSION['user'])){
            header('Location: /user/login');
        }
        $this->model = new Model_main();

    }

    function index()
    {


        $data['users'] = $this->get_users();

        $data['posts'] = $this->model->get_posts();


        $this->view->generate('main_view.php', $data);

    }

    public function createpost(){
        if(isset($_POST['caption'], $_POST['post'])){
            $this->model->create_post($_POST['caption'], $_POST['post']);
        }
        header('Location: /');
    }

    public function post($id){
        if(!$id) Route::ErrorPage404();
        $data['post'] = $this->model->get_post($id);
        $data['users'] = $this->get_users();
        var_dump($data);

    }

    private function get_users(): array
    {
        include 'app/models/model_user.php';
        $users_model = new Model_user();
        $users = $users_model->get_users();
        $ret = [];
        foreach ($users as $u)
            $ret[$u['id']] = $u['login'];
        return $ret;
    }
}