Object to array

[xionhack]

Hello. I have a problem, when I instantiate an object from inside the class and then pass it to any page, then it appears as an array, and for me to echo it i have to do something like $array[0][name]->whatever, and Its really annoying. Im very new at object oriented programming and I think there is something Im missing, any help? Thanks!

[leehanken]

I am not sure what you mean about an object turning into an array. Have you tried using print_r, for example:

<?php

class x {
public $p;
public $q;
function __construct() {
$this->p=10;
$this->q=20;
}
};

$a = new x();

print_r($a);

?>

 

produces

 

x Object
(
    [p] => 10
    [q] => 20
)

 

[xionhack]

[syntax=php]

class DatabaseObject {

public static function find_by_sql($sql="") {

    global $database;

    $result_set = $database->query($sql);

    $object_array = array();

    while ($row = $database->fetch_array($result_set)) {

      $object_array[] = static::instantiate($row);

    }

    return $object_array;

  }

 

 

protected static function instantiate($record) {

// Could check that $record exists and is an array

    $object = new static;

// Simple, long-form approach:

// $object->id = $record['id'];

// $object->username = $record['username'];

// $object->password = $record['password'];

// $object->first_name = $record['first_name'];

// $object->last_name = $record['last_name'];

 

// More dynamic, short-form approach:

foreach($record as $attribute=>$value){

  if($object->has_attribute($attribute)) {

    $object->$attribute = $value;

  }

}

return $object;

}

 

private function has_attribute($attribute) {

  // We don't care about the value, we just want to know if the key exists

  // Will return true or false

  return array_key_exists($attribute, $this->attributes());

}

 

protected function attributes() {

// return an array of attribute names and their values

  $attributes = array();

  foreach(static::$db_fields as $field) {

    if(property_exists($this, $field)) {

      $attributes[$field] = $this->$field;

    }

  }

  return $attributes;

}

 

[/syntax]

 

 

 

 

 

[syntax=php]

class Schedule extends DatabaseObject {

protected static $id_name = "schedule_id";

protected static $table_name="scheduled_studies";

protected static $db_fields = array('schedule_id', 'student_id', 'teacher_id', 'lesson', 'date' , 'time');

 

public $schedule_id;

public $student_id;

public $teacher_id;

public $date;

public $time;

public $lesson;

 

      public static function find_last_study($student_id) {

$sql =  "SELECT * FROM " . self::$table_name . " WHERE stuent_id= {$stuent_id}

  ORDER BY date, time DESC";

 

$last_study = parent::find_by_sql($sql);

 

return $last_study;

}

[/syntax]

 

Then If I do this

 

[syntax=php]

<?php echo $last_study = Schedule::find_last_study(1); ?>

 

 

[/syntax]

 

It will return an array with the object in it, not just the object. Let me know if it makes sense.

[KevinM1]

It returns an array because find_by_sql returns an array.

 

As an aside, are you sure that you're getting objects back from your instantiate method?  'Static' is a PHP keyword.  I doubt it can be used as the name of a class (i.e., '$object = new static;').

[xionhack]

its because im using late static binding.

[leehanken]

Nightslyr is right that the function returns an array. I think the following will give what you want, limiting the query to 1 record, and returning just the first (and only) element in the array - your object.

 

class Schedule extends DatabaseObject {
protected static $id_name = "schedule_id";
   protected static $table_name="scheduled_studies";
   protected static $db_fields = array('schedule_id', 'student_id', 'teacher_id', 'lesson', 'date' , 'time');
   
   public $schedule_id;
   public $student_id;
   public $teacher_id;   
   public $date;
   public $time;
   public $lesson;

       public static function find_last_study($student_id) {      
      $sql =  "SELECT * FROM " . self::$table_name . " WHERE stuent_id= {$stuent_id}
              ORDER BY date, time DESC LIMIT 1";
              
            $last_study = parent::find_by_sql($sql);
                     
            return $last_study[0];
   }
...

 

Also you will need to declare __toString in the Schedule class definition so you can print the object with echo.

 

public function __toString() {
return  $this->schedule_id . " " . $this->student_id . " " . $this->teacher_id . " " . $this->date . " " . $this->time . " " . $this->lesson;
}

 

[xionhack]

Thats what I was doing, but because im new at this i diddnt know if thats the best way to do it. Anybody has a better way? Thanks!

[leehanken]

One way of doing things, would be to get find_by_sql() to return an array if there are multiple rows, but return an object if there is just one row.

 

public static function find_by_sql($sql="") {
    global $database;
    $result_set = $database->query($sql);
    $object_array = array();
    while ($row = $database->fetch_array($result_set)) {
      $object_array[] = static::instantiate($row);
    }
    if (count($object_array)==1) return $object_array[0];
    else return $object_array;
  }

 

I don't know if this solution is aesthetically perfect, but I have seen it done in other people's code and it is the best I can think of.