You're already doing it!
save() will check if something in the model has changed. If it hasn't it won't run a db query.
Here's the relevant part of code in Illuminate\Database\Eloquent\Model@performUpdate:
protected function performUpdate(Builder $query, array $options = [])
{
$dirty = $this->getDirty();
if (count($dirty) > 0)
{
// runs update query
}
return true;
}
The getDirty() method simply compares the current attributes with a copy saved in original when the model is created. This is done in the syncOriginal() method:
public function __construct(array $attributes = array())
{
$this->bootIfNotBooted();
$this->syncOriginal();
$this->fill($attributes);
}
public function syncOriginal()
{
$this->original = $this->attributes;
return $this;
}
If you want to check if the model is dirty just call isDirty():
if($product->isDirty()){
// changes have been made
}
Or if you want to check a certain attribute:
if($product->isDirty('price')){
// price has changed
}