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Thread: Double Dependency Injection?

  1. #1
    Private Whiskas's Avatar
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    Double Dependency Injection?

    Maybe someone smart can help figure it out for me.

    I am making some website with accounts etc. On the index page, there is a form to login. After clicking Sign in button, this is executed:
    PHP Code:
    $userService = new UserService($mysqli$_POST['identity_number'], $_POST['password']);
        if (
    $userService->login()) {
            
    $_SESSION[user] = $userService->getUser();        
            
    header("Location: home.php");
        } 
    I am creating object of UserService class, which looks like this:

    PHP Code:
    class UserService
    {
        protected 
    $_id;
        protected 
    $_passwd;

        public 
    $_db;
        public 
    $_user;

        public function 
    __construct(mysqli $db$id$passwd)
        {
            
    $this->_db $db;
            
    $this->_id $id;
            
    $this->_passwd $passwd;
        }

        public function 
    login()
        {
            
    $user $this->_checkCredentials();
            if (
    $user) {
                
    $this->_user = new User($this->_db$user->iduzytkownika$user->imie$user->nazwisko$user->idgrupy$user->idpodgrupy);
                
    print_r($this->_db);
                
    print_r($this->_user);
                return 
    $user;
            }
            return 
    false;
        }

        protected function 
    _checkCredentials()
        {
            
    $this->_id $this->_db->real_escape_string($this->_id);
            
    $this->_passwd $this->_db->real_escape_string($this->_passwd);
            
    $result $this->_db->query("SELECT * FROM uzytkownicy WHERE iduzytkownika = $this->_id AND passwd = '$this->_passwd'");

            if(
    $result)
                return 
    $result->fetch_object();

            return 
    false;
        }

        public function 
    getUser()
        {
            return 
    $this->_user;
        }

    Everything is working fine, if the id and password is properly, new User class object is created, which looks like this:

    PHP Code:
    class User
    {
        public 
    $_id;
        public 
    $_name;
        public 
    $_lastname;
        public 
    $_groupID;
        public 
    $_subgroupID;
        public 
    $_db;

        public function 
    __construct(mysqli $db$id$name$lastname$groupID$subgroupID)
        {
            
    $this->_db $db;
            
    $this->_id $id;
            
    $this->_name $name;
            
    $this->_lastname $lastname;
            
    $this->_groupID $groupID;
            
    $this->_subgroupID $subgroupID;
        }

        public function 
    __toString()
        {
            return 
    $this->_name " " $this->_lastname;
        }

        public function 
    getUserGroups()
        {
            
    print_r($this->_db); // For the debug purposes        
        
    }

    And there comes the problem with $db mysqli object, which despites having proper structure (of mysqli class), all the values are empty. print_r from getUserGroups() returns:

    PHP Code:
     mysqli Object
    (
        [
    affected_rows] =>
        [
    client_info] =>
        [
    client_version] => 50012
        
    [connect_errno] => 0
        
    [connect_error] => 
        [
    errno] => 
        [
    error] => 
        [
    error_list] => 
        [
    field_count] => 
        [
    host_info] => 
        [
    info] => 
        [
    insert_id] => 
        [
    server_info] => 
        [
    server_version] => 
        [
    stat] => 
        [
    sqlstate] => 
        [
    protocol_version] => 
        [
    thread_id] => 
        [
    warning_count] => 

    I would like to note that mysqli object in UserService ain't empty.

    Anyone got a clue to fix it or even properly name that problem. Cause I have trouble finding similar posts to mine.

    Thanks in advance,

    Whisky

  2. #2
    Assadministrator kung foo man's Avatar
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    PHP Code:
    $_SESSION[user] = $userService->getUser(); 
    A session entry is a serialized piece of data, which cannot hold any resource variables. Either read the stuff you need directly at login time and serialize it into $_SESSION (when the resource is still valid), or, better way IMHO, read the stuff you need every time a user opens the page, so you don't have any out-of-sync data.
    i scroll at stuff

  3. The Following User Says Thank You to kung foo man For This Useful Post:

    Whiskas (20th November 2016)

  4. #3
    Private Whiskas's Avatar
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    Quote Originally Posted by kung foo man View Post
    PHP Code:
    $_SESSION[user] = $userService->getUser(); 
    A session entry is a serialized piece of data, which cannot hold any resource variables.
    Thanks this is the thing I needed to know. I was wrongly thinking that mysqli object was the main problem.

    Quote Originally Posted by kung foo man View Post
    read the stuff you need every time a user opens the page, so you don't have any out-of-sync data.
    I wanted to make global user class object that would have functions (with mysql queries) returning appropriate data.

    Like $user->getSomething(); and it would return information from the database about that something (groups this user belongs etc).

    So, now my problem is finding a way to make global object.
    Attempt:

    index.php
    PHP Code:
    global $user;

    if (isset(
    $user)) {
        
    header("Location: home.php");
    }

    if (isset(
    $_POST['btn-login'])) {

        
    $userService = new UserService($mysqli$_POST['identity_number'], $_POST['password']);
        if (
    $userService->login()) {
            
    $user $userService->getUser();
            
    header("Location: home.php");
        }

    home.php
    PHP Code:
    global $user;

    if (!isset(
    $user))
        
    header("Location: index.php"); 
    After moving to home.php variable $user isn't set..

    Reading most comments over this problem directs to Singleton Pattern, but personally I have no clue, how to pass parameters to the instance, so it could contain $id, $name etc.

    PHP Code:
    class Singleton {
        private static 
    $instance;

        private function 
    __construct() {}
        private function 
    __clone() {}

        public static function 
    getInstance() {
            if (!
    Singleton::$instance instanceof self) {
                 
    Singleton::$instance = new self();
            }
            return 
    Singleton::$instance;
        }

        public function 
    DoSomething() {
            ...
        }

    Any known sollution to make class object globl score?

    Thanks again for your help.

    EDIT:

    I found sollution:

    PHP Code:
    <?php

    /**
     * Created by PhpStorm.
     * User: Meh
     * Date: 20.11.2016
     * Time: 12:51
     */
    class DB extends MySQLi {
        private static 
    $instance null ;

        private 
    $host 'localhost';
        private 
    $user "root";
        private 
    $password "Wilki0101";
        private 
    $database "mydb";

        public function 
    __construct($host$user$password$database){
            
    parent::__construct($host$user$password$database);
        }

        public static function 
    getInstance(){
            if (
    self::$instance == null){
                
    self::$instance = new self('localhost'"user""pass""db");
            }
            return 
    self::$instance ;
        }
    }
    Now, when the Class user needs to make queries, it just get's an instance like that:

    PHP Code:
    include "DB.php";

    class 
    User
    {
        
    //private static $instance;
        
    public $_id;
        public 
    $_name;
        public 
    $_lastname;
        public 
    $_groupID;
        public 
    $_subgroupID;
        protected 
    $_db;

        public function 
    __construct($id$name$lastname$groupID$subgroupID)
        {
            
    $this->_id $id;
            
    $this->_name $name;
            
    $this->_lastname $lastname;
            
    $this->_groupID $groupID;
            
    $this->_subgroupID $subgroupID;
        }

        public function 
    __toString()
        {
            return 
    $this->_name " " $this->_lastname;
        }

        public function 
    getUserGroups()
        {
            
    $this->_db DB::getInstance();

            
    $result $this->_db->query("select p.idpodgrupy, p.nazwapodgrupy from podgrupy p
                                    join grupy_podgrupy g
                                    on p.idpodgrupy=g.idpodgrupy
                                    join grupy gp
                                    on gp.idgrupy = g.idgrupy
                                    join uzytkownicy u
                                    on u.idgrupy = gp.idgrupy
                                    where u.iduzytkownika = 16"
    );

            
    print_r($result);    
        }

    And the $results aren't empty.

    Thanks anyway kung for your tip with $_SESSION!
    Last edited by Whiskas; 20th November 2016 at 13:29.

  5. #4
    Assadministrator kung foo man's Avatar
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    What you try is not possible with PHP, the interpreter is basically resetted for every page request. That's why you need to reinitialize the needed data at every page request via new database queries.

    When you need "sticky" variables, you could try node.js http server. The interpreter isn't "detached" behind by e.g. a FastCGI wall from the web server.

    For PHP, just make a table relation between the $_COOKIE["PHPSESSID"] and the stuff you want to cache (e.g. which groups the user belongs to). Normally tho you just save the most important stuff like the session expiration time of the session and the user id, so the home.php has a way to know that the user is logged in via checking the cookie session ID against the session table.

    You are welcome ^^
    i scroll at stuff

  6. The Following User Says Thank You to kung foo man For This Useful Post:

    Whiskas (20th November 2016)

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