WP_Model-helper-properties.php

<?php
$product = new Product;
$product->new;                 // Returns (bool) true
$product = Product::find(15);
$product->new;                 // Returns (bool) false

$product->color = 'red';
$product->dirty;   // Returns (bool) true
$product->save();
$product->dirty;   // Returns (bool) false

$product->title;   // Returns the post title

$product->content; // Returns the post content