How to create constructor with optional parameters? [duplicate]

Answer 1

public function __construct() {
    // allocate your stuff
}

public static function withRow( array $row ) {
    $instance = new self();
    $instance->fill( $row );
    return $instance;
}

protected function fill( array $row ) {
    // fill all properties from array
}

For details check this answer : Best way to do multiple constructors in PHP

Answer 2

Thank you very much for your answer. I have solved the problem with my way.

public function __construct($nick) {
    if($nick != NULL) {//for user 
        $query = "SELECT * FROM Users WHERE nick='".$nick."'";
        $result = App::runQuery($query);
        $user = $result->fetch_object();

        $this->id = $user->id;
        $this->nick = $user->nick;
        $this->email = $user->email;
        $this->password = $user->password;
        $this->birthDay = $user->birthDay;
        $this->sex = $user->sex;
        $this->about = $user->about;
        $this->city = $user->city;
        $this->photo = $user->photo;
        $this->following = $user->following;
        $this->followers = $user->followers;
        $this->statu = $user->statu; 
    }else {//for null
        $this->id = NULL;
        $this->nick = NULL;
        $this->email = NULL;
        $this->password = NULL;
        $this->birthDay = NULL;
        $this->sex = NULL;
        $this->about = NULL;
        $this->city = NULL;
        $this->photo = NULL;
        $this->following = NULL;
        $this->followers = NULL;
        $this->statu = NULL;
    }

}

It works!

Answer 3

1. There is no overloading in PHP; you cannot have methods with the same names but different parameters

2. Since all of your properties will default to null, there's no reason to do it yourself. I would suggest doing the following:

   public function __construct($nick = null) {
       if ($nick != null) {
           $query = "SELECT * FROM Users WHERE nick='".$nick."'";
           $result = App::runQuery($query);
           $user = $result->fetch_object();
   
           $this->id = $user->id;
           $this->nick = $user->nick;
           $this->email = $user->email;
           $this->password = $user->password;
           $this->birthDay = $user->birthDay;
           $this->sex = $user->sex;
           $this->about = $user->about;
           $this->city = $user->city;
           $this->photo = $user->photo;
           $this->following = $user->following;
           $this->followers = $user->followers;
           $this->statu = $user->statu; 
       }
   }
   

3. An alternative to the above code is to have multiple, static constructor methods, and use a private constructor:

   private function __construct() {
   }
   
   public static function createFromNick($nick) {
       $self = new self();
   
       $query = "SELECT * FROM Users WHERE nick='".$nick."'";
       $result = App::runQuery($query);
       $user = $result->fetch_object();
   
       $self->id = $user->id;
       $self->nick = $user->nick;
       $self->email = $user->email;
       $self->password = $user->password;
       $self->birthDay = $user->birthDay;
       $self->sex = $user->sex;
       $self->about = $user->about;
       $self->city = $user->city;
       $self->photo = $user->photo;
       $self->following = $user->following;
       $self->followers = $user->followers;
       $self->statu = $user->statu;
   
       return $self;
   }
   
   public static function createEmpty() {
       return new self();
   }