- [Comparing Cast Values](#comparing-cast-values)

<a name="comparing-cast-values"></a>

If you would like to define how two given cast values should be compared to determine if they have been changed, your custom cast class may implement the `Illuminate\Contracts\Database\Eloquent\ComparesCastableAttributes` interface. This allows you to have fine-grained control over which values Eloquent considers changed and thus saves to the database when a model is updated.

This interface states that your class should contain a `compare` method which should return `true` if the given values are different:

/**

* Determine if the given values are equal.

*

* @param \Illuminate\Database\Eloquent\Model $model

* @param string $key

* @param mixed $firstValue

* @param mixed $secondValue

* @return bool

*/

public function compare(

Model $model,

string $key,

mixed $firstValue,

mixed $secondValue

): bool {

return $firstValue !== $secondValue;

}