Laravel4 - Track changes to be saved by Eloquent - php

Question

In Laravel 4, I have a class extending Eloquent and I need to record changes (to keep the history) at the time of saving.
Saving event in boot function is called as expected. The question is: how do I know which fields were changed and are about to be saved? Also, can I access existing values without loading the record again?
I know, one way could be to load the record again and compare all fields one by one. Is there any better optimized way to do that?
class Record extends Eloquent {
protected static function boot()
{
parent::boot();
static::saving(
function($record)
{
// It runs properly. This is where changes should be compared
return true;
}
);
}
}
Thank you.

Answer 1

Eloquent's getDirty() and getOriginal() did the trick:
static::saving(
function($record)
{
$dirty = $record->getDirty();
foreach ($dirty as $field => $newdata)
{
$olddata = $record->getOriginal($field);
if ($olddata != $newdata)
{
// save changes from $olddata to $newdata
}
}
return true;
}
);

Answer 2

I don't think accepted answer is the best way to do that. Why would you loop through all changed fields to figure out what has changed? Laravel has this two Model methods that can help you better,
on save function/route/controller whichever you use
$model::find(X);
...
'''
$model->fill(Input::all());
if( !empty($model->getDirty() )
// Get status of model. if nothing has changed there is no need to get in here
{
if($model->isDirty( { mixed data (array,string,null) } ))
// isDirty() will help you to find out if the field is different than original
{
.....
enter code here
....
}
}

Answer 3

You can use events:
Event::listen('saving', function($model)
{
// Do whatever you need to do with your $model before saving or not:
return true;
});
You can also hook that saving method to any controller action:
Event::listen('saving', 'LogThings#saving');

Answer 4

I have something like this in my project.
Record::updating(function($record){
$original = $record->getOriginal();
foreach($original as $index => $value){
if($index != 'updated_at' AND $index != 'created_at'){
if($value != $record[$index]){
RecordUpdate::create(array('record_id' => $record->id, 'fieldname' => $index, 'old_value' => $value, 'new_value' => $record[$index], 'created_at' => date('Y-m-d H:i:s')));
}
}
}
});

Answer 5

The Eloquent class that you're extending has getOriginal() and getAttributes() methods to get the originally-hydrated properties and the currently set properties, respectively.
So, in your saving event you can do something like...
if ( ! empty( array_diff( $record->getOriginal(), $record->getAttributes() ) ) )
{
//log changes
}
If you want to do this for all/most of your Models, I suggest abstracting this out to a generic Model Observer:
////
/* Subclassable, generic Model Observer */
////
class ModelObserver {
public function saving($model)
{
if ( ! empty( array_diff( $record->getOriginal(), $record->getAttributes() ) ) )
{
//log changes
}
}
}
////
/* Set up observers, for example in start/global.php */
////
$modelObserver = new ModelObserver;
Comment::observe($modelObserver);
Post::observe($modelObserver);
User::observe($modelObserver);