Question

What’s the right way to send user input to a class?

Foo class:

<?php
class Foo
{
    private $_bar;

    private setBar($bar)
    {
        $this->_bar = $bar;
    }
}
?>

Using foo class…

<?php
$foo = new Foo();
$foo->setBar((int) $_POST['input']);
?>

Or should I do the following?

Foo class:

<?php
class Foo
{
    private $_bar;

    private setBar($bar)
    {
        $this->_bar = (int) $bar;
    }
}
?>

Using foo class…

<?php
$foo = new Foo();
$foo->setBar($_POST['input']);
?>

Should I convert data inside of the get method or pass data to classes already converted? What’s the best approach? Why?

Answer 1

Better yet would be to validate by an exception. If you add another method like:

public function calculateSalary() {
  // uses bar, wants int
  return 100 * $this->_bar;
}

and someone uses the class like this:

$foo = new Foo();
$foo->setBar('My Name Here');
echo $foo->calculateSalary(); // will give a result since php is forgiving

To avoid mishaps like these, I write setters similar to this:

public function setFoo($number) {
  if(!is_numeric($number)) {
    throw new Exception(__METHOD__." wants a number!");
  }
  $this->_foo = $number;
}

---

Arguments against #1: user might not include (int) and therefor data with the wrong type is set in the object.

Arguments against #2: (see example above). PHP is translating a string to 0 if used while calculating. That means you probably will get an error without even knowing about it until you check the results.