Laravel - Set data to null before deleting column from other table - php

Question

I have 2 tables. (1) being users, and (2) being foods.
In the [users] table, there is a food_id bracket that is linked as a foreign key to an item/column's id in the other table [foods].
I am able to make a reservation of a [food] column, although I want to be able to press a 'confirm' button on the item once reserved, which will delete the item's targetted column in the Database.
Although since both tables are linked with a foreign key, I know that I need to set the parent key to null in order to be able to fully delete the target column. Otherwise it throws me an error that I can't delete/update a parent item with children objects.
(my food's object primary ID being linked to the authenticated user's food_id foreign key.)
This current code I tried only throws me the following error: "Call to a member function onDelete() on null"
$foodsId = User::find(auth()->user()->foods_id);
$foodsId->onDelete('set null');
$foodsId->save();
$foodDel = Foods::find($id);
$foodDel->delete();
Don't exactly know what to think here.

Answer 1

You could edit the foreign key constraint to do this automatically, but what you're trying to do can be done with these lines.
$food = Food::findOrFail(auth()->user()->food_id);
auth()->user()->fill(['food_id' => null])->save(); // use forceFill() if food_id is not in the User's fillable fields.
$food->delete();
To have this happen automatically, you could make a migration with the command
php artisan make:migration changeFoodIdForeignKeyConstraint --table=users
function up()
{
Schema::table('users', function (Blueprint $table) {
$table->dropForeign(['food_id']);
$table->foreign('food_id')
->references('id')->on('foods')
->onUpdate('cascade')
->onDelete('set null');
});
}
Another option is to use a model event on the Food model
class Food extends Model
{
/**
* The "booted" method of the model.
*
* #return void
*/
protected static function booted()
{
static::deleting(function ($food) {
User::where('food_id', $food->id)->update(['food_id' => null]);
});
}

Answer 2

Actually have found my own solution. I went to directly target my first foreign key, to then asign a null parameter to it, THEN fetch the targetted ID of my item and delete its column.
$user = auth()->user();
$user->food_id = null;
$foodDel = Foods::find($id);
$foodDel->delete();