Add a training after payment - laravel

Question

I have 3 form, the first is the form students with 2 fields (name, firstname)
Then, we have the form payments with 3 fields (date_encoding, price, fk_student)
And finally, the last form trainings with 3 fields (date_sitting, fk_student, fk_payment).
My problem is the form trainings, I can create a new record without the payment of a student.
Is it possible to block a record with an error message in the training form?
Here is an idea of my code for now.
public function store(Request $request)
{
$request->validate([
'date_sitting' => 'required|date',
'fk_student' => 'required',
'fk_payment' => 'required'
]);
$exists = Training::where('date_sitting', $request->get('date_sitting'))->where('fk_student', $request->get('fk_student'))->where('fk_payment', $request->get('fk_payment'))->count();
if (!$exists){
Training::create($request->all());
return redirect()->route('trainings.index')
->with('success', 'new data created successfully');
}
else{
return redirect()->route('trainings.index')
->with('error', 'duplicate');
}
}

Answer 1

Sure - just add an if-check inside the creation block. If the user doesn't have a payment, don't create and return an error message. You can do this by redirect like you have it, or you can even have a separate check via AJAX to just see if there is a payment, similar to the if-check I add below on $payment.
However, to keep it simple & continue as you have it, something like this:
if (!$exists){
// Is there a payment for the student trying to create a training?
$payment = Payment::where('fk_student', $request->get('fk_student'))->first()
// You may wish to add some kind of date check to see if they paid for a specific training
if(!isset($payment)){ // No payment = block creation and return error msg.
return redirect()->route('trainings.index')
->with('error', 'No Payment, no training for you!');
}
else{
Training::create($request->all());
return redirect()->route('trainings.index')
->with('success', 'new data created successfully');
}
}