Laravel 8 save integer into null DB column - save vs update - laravel-8

Question

I'm having an interesting issue where Laravel's save() does not replace null values in database, while the update() does. I also tested by manually changing null to 1 and afterwards the save() started updating the column. I am using save() throughout the project and would prefer that it stays that way or that at least I understand the problem before I go changing the code.
Migration (all codes will be partial extracts for brewity):
$table->foreignId('checklist_id')->nullable()->constrained('checklists')->onUpdate('cascade')->onDelete('cascade');
$table->foreignId('action_id')->nullable()->constrained('actions')->onUpdate('cascade')->onDelete('cascade');
Model (added the checklist_id and action_id for testing, otherwise they are not here):
// test
protected $fillable = [
'checklist_id',
'action_id',
];
protected $casts = [
'checklist_id' => 'integer',
'action_id' => 'integer',
];
// actual
protected $fillable = [
];
protected $casts = [
];
Controller:
public function update(UpdateWorkOrderRequest $request, WorkOrder $workOrder)
{
$response = $workOrder->save($request->all());
}
Form submission (from Chrome):
------WebKitFormBoundary73Z4wzsmsGcgOOAM
Content-Disposition: form-data; name="checklist_id"
1
------WebKitFormBoundary73Z4wzsmsGcgOOAM
Content-Disposition: form-data; name="action_id"
1
dd($request->all()):
array:2 [▼
"checklist_id" => "1"
"action_id" => "1"
]
The fields checklist_id and action_id are null after using save(), but they do get updated using update(). It's also working if I do this:
$workOrder->checklist_id = $request->checklist_id;
$workOrder->action_id = $request->action_id;
$workOrder->save();
I opted for save() to write less code instead of above example and because from docs I presume I can use save() when assigning data from $request, like here: https://laravel.com/docs/9.x/eloquent#updates

Answer 1

As discussed in the comments, you're trying to use model->save(attributes).
The save function does not provide any parameters for this. (docs).
You have two options, either use the model->update function (docs):
$workOrder->update($request->all());
Or use the model->fill (docs) function in combination with model->save like so:
$workOrder->fill($request->all())->save();