How Laravel Eloquent's save() Really Works Under the Hood

Laravel's Eloquent save() method does far more than fire a simple SQL query — its behavior is governed by a boolean property called $exists, which determines whether the operation runs an INSERT or an UPDATE. Before any SQL executes, Eloquent fires a sequence of model events such as saving, creating, and updating, and if any event listener returns false, the save is silently cancelled with no query run. Laravel also performs dirty checking, meaning only columns whose values have actually changed since the model was loaded are included in the UPDATE statement, making no-op saves possible when nothing has changed. Cloning a model without resetting $exists and the primary key will update the original database record rather than creating a new one, a common source of hard-to-trace bugs. Understanding these internal steps — event firing, dirty tracking, and the $exists flag — helps developers debug unexpected Eloquent behavior more effectively.