PHP Class Dependent on another Class

Question

I have the following problem - lets say I have a class named Database

class Database
{
   public function insert(...)
   {
    //insert something in the database
   }
}

And I have a class named User

class User
{
   public function register(..)
   {
       //validate the user , and insert him
       //here i need to call insert() function from Database class
   }
}

Is there a simple way in which I can call the insert method inside the User class?

`dependency injection` - perhaps might be of interest http://php-di.org/doc/understanding-di.html and / or https://stackoverflow.com/questions/130794/what-is-dependency-injection — Professor Abronsius, Feb 11 '18 at 14:35
Does your `Database` class need to be instanciated? Why not make it static? — Syscall, Feb 11 '18 at 14:37
Syscall , no i can make it static , then just include it and call Database::insert(...) ? Is this correct , i`m new to OOP — Ivan Ivanov, Feb 11 '18 at 14:41
Yes. `static public function insert()`, then in `register()`, use `Database::insert(...)`. — Syscall, Feb 11 '18 at 14:42
PetarPirev, @RamRaider is right, dependency injection is the way to go. **Make your classes' dependencies explicit**. — ishegg, Feb 11 '18 at 14:43
Syscall , thanks , how to mark your comment as a correct answer ? — Ivan Ivanov, Feb 11 '18 at 14:43
ishegg , i heard about that , but it`s like complex to me , with these controllers and such — Ivan Ivanov, Feb 11 '18 at 14:45
Petar, it certainly has a learning curve, but trust me, you will be thanking yourself in the long run. It'll be much more maintainable and readable. — ishegg, Feb 11 '18 at 14:47

score 2 · Accepted Answer · answered Feb 11 '18 at 14:47

using dependency injection you would typically do it something like this

class Database
{
   public function insert(...)
   {
    //insert something in the database
   }
}


class User
{
   private $db;
   public function __construct($db){
        $this->db=$db
   }
   public function register(..)
   {
       //validate the user , and insert him
       //here i need to call insert() function from Database class

       $this->db->insert();
   }
}

$db=new Database();
$usr=new User( $db );
$usr->register();

score 0 · Answer 2 · answered Feb 11 '18 at 14:40

Just make an object in the user class and call the method in it like

class User
{
public function register(..)
 {
   //validate the user , and insert him
   //here i need to call insert() function from Database class
 $useit= new Database; //assign an object of type database
  $useit->insert();  //call the method like this
 }
}

score -1 · Answer 3 · answered Feb 11 '18 at 14:49

Create an instance of the class you want to import in the constructor of the class you're importing it to.

class User {
    private $database;

    public function __construct() {
        $this->database = new Database;
    }

    public function register() {
        $this->database->insert();
    }
}

class Database {
    public function insert() {
    }
}

$user = new User;
$user->register();

This answer should help. You can access all methods and properties of the Database class by referencing $this->database.

Clear way to do this is dependency injection through constructor method. otherwise you can't do unit testing and this is bad pattern — Alex, Jun 22 '23 at 08:43

PHP Class Dependent on another Class

3 Answers3