repo.php

<?php

class Repository
{

	const TABLE = 'contacts';

/* snip */

	public function edit(Contact $contact)
	{
		$data = array_filter($contact->asArray());
		unset($data['id']); // never update id
		$query = DB::update(self::TABLE)
			->set($data)
			->where('id', '=', $contact->id)
			;
		$count = $query->execute();
		return TRUE;
	}
}