[12.x] Add $key parameter to getChanges() and getPrevious() methods

[stevebauman]

This PR adds optional $key and $default parameters to the getChanges() and getPrevious() methods in the HasAttributes trait, allowing developers to retrieve specific changed or previous attribute values directly:

Before:

$changedName = $user->getChanges()['name'] ?? null;
$previousTitle = $user->getPrevious()['title'] ?? 'default';

After:

$changedName = $user->getChanges('name');
$previousTitle = $user->getPrevious('title', 'default');

This aligns directly with the existing getOriginal method:

framework/src/Illuminate/Database/Eloquent/Concerns/HasAttributes.php

Lines 1986 to 1998 in 6d26643

	/**
	* Get the model's original attribute values.
	*
	* @param string|null $key
	* @param mixed $default
	* @return ($key is null ? array<string, mixed> : mixed)
	*/
	public function getOriginal($key = null, $default = null)
	{
	return (new static)->setRawAttributes(
	$this->original, $sync = true
	)->getOriginalWithoutRewindingModel($key, $default);
	}

This may be considered to be a breaking change, since developers who have overridden getPrevious()/getChanges() would have to support these new parameters. Otherwise they will receive this error:

Fatal error: Declaration of ...getPrevious() must be compatible with Illuminate\Database\Eloquent\Model::getPrevious($key = null, $default = null)

I can target Laravel 13 if you prefer -- let me know! Thanks for your time!

[macropay-solutions]

You can avoid extra steps if key is null and just return early. Valid for getPrevious also.

[macropay-solutions]

Still to avoid the return type change, maybe new functions would better suit this case getChange, getPreviousByKey.

[stevebauman]

Thanks for the review!

The additions in this PR are nearly identical to the existing getOriginal method, so I'll wait for the Laravel team's thoughts on this before changing 👍

[macropay-solutions]

Ok. Following old paths is not always the best thing to do because if those paths are wrong... Multi-return type is one of those wrong paths to follow. Also introducing more steps if $key is null is another bad path.

[stevebauman]

Consistency is far more important for the longevity of codebase. Implementing new ways of doing things when an existing pattern already exists fragments codebases and causes developer turmoil.

[taylorotwell]

Thanks for your pull request to Laravel!

Unfortunately, I'm going to delay merging this code for now. To preserve our ability to adequately maintain the framework, we need to be very careful regarding the amount of code we include.

If applicable, please consider releasing your code as a package so that the community can still take advantage of your contributions!

[taylorotwell]

Could this be a breaking change because we are transforming model values in those methods you're calling?

[stevebauman]

@taylorotwell Yes thats correct! No problem though -- can maybe look at this again in the future 👍