Can I check if a model attribute has changed to same value?

Is there some way I can hook into the updating of a model so I can detect these changes?

Why yes, yes there is... Events

Within the event you can then use ->getOriginal($fieldname) to get the previous value. So in your case, for price:

if ($obj->price != $obj->getOriginal('price')) {
  // A change to the price has occurred.
  $obj->price_updated_at = Carbon::now()->toDateTimeString();
}

EDIT: looking at your scenario again, it looks like regardless if the price has changed or not you want to update the time? So basically any time a price is updated from this external API you want the time updated, yes? Why not just do that at that time? Cron runs, and sees an old price, so a call is made to a 3rd party API.. price is updated (to same, or new value) .. update price_updated_at field to current time, save. Unless I'm misunderstanding something, it sounds like you're overcomplicating things by not just updating the timestamp when you update the price.

Why yes, yes there is... Events

Thanks for the response. I'm actually already using the saving event. I was hoping there was something like isDirty that let's me know if the field has been updated at all, not just if it's value has been changed. Hope that makes sense.

EDIT: looking at your scenario again, it looks like regardless if the price has changed or not you want to update the time? So basically any time a price is updated from this external API you want the time updated, yes? Why not just do that at that time? Cron runs, and sees an old price, so a call is made to a 3rd party API.. price is updated (to same, or new value) .. update price_updated_at field to current time, save.

I could definitely do that. I was just hoping to abstract it away so that any logic related to the price_updated_at field can be tucked away into a single observer and forgotten about.

try this approach https://github.com/fico7489/laravel-revisionable-upgrade

I recently published a package to save you from all the boilerplate of tracking/observing and reacting to model attribute changes.

Check it out here: alexstewartja/laravel-attribute-observer