Get previous attribute value in Eloquent model event

问题

Is there a way to see the old/previous value of a model's attribute in its saving or updating event?

eg. Is something like the following possible:

User::updating(function($user)
{
    if ($user->username != $user->old->username) doSomething();
});

回答1:

Ok, I found this quite by chance, as it's not in the documentation at present...

There is a getOriginal() method available which returns an array of the original attribute values:

User::updating(function($user)
{
    $original = $user->getOriginal();
    if ($user->username != $original['username']) {
        doSomething();
    }
});

Laravel strikes again!

Be carefult, it ignores the model type casting.

回答2:

In Laravel 4.0 and 4.1, you can check with isDirty() method:

User::updating(function($user)
{
    if ($user->isDirty('username')){
        doSomething();
    }
});

回答3:

You could overload the methods, then call the parent method.

来源：https://stackoverflow.com/questions/17367383/get-previous-attribute-value-in-eloquent-model-event