Livewire validation with custom rule and additional parameters

Question

I have a Form where a timeslot (the validating field) might be valid for employee A (another field in the component), but not for employee B.

I have a custom validation Rule TimeSlotEmployee that checks for the correctness of the combination (employee, timeslot) through request('employee_id') and the $value parameter of the passes function, and so far it works fine.

I'm now moving this form into a Livewire component, but I'm facing difficulties because in the POST request that is triggered by the update of the timeslot field there is no employee_id, only the new timeslot value.

How can I solve this problem? Am I tackling it from the wrong angle?

Update

This is the rules function inside the TimeSlotRequest:

public function rules()
{
  return [
    'employee_id' => ['required', 'numeric'],
    'timeslot' => ['required', new TimeSlotEmployeeRule()],
  ];
}

In the TimeSlotEmployeeRule, this is the passes function:

public function passes($attribute, $value)
{
    $timesloteValue = Carbon::createFromFormat('d-m-Y H:i', $value);
    $employee = Employee::find(request('employee_id'));

    // perform checks: this part works, but requires the employee instance

   return true;
}

In the Livewire component, I use the standard updated method:

public function updated($propertyName)
{
    $this->validateOnly($propertyName);
}

Answer 1

Since the request in Livewire needs to rehydrate the component, you can never fully depend on the request() helper, particularly in subrequests - as the data being passed is Livewire's data.

You should pass the value as a parameter to the rule instead, like so,

<?php

namespace App\Rules;

use Illuminate\Contracts\Validation\Rule;

class TimeSlotEmployeeRule implements Rule
{
    public int $employee_id;

    public function __construct($employee_id)
    {
        $this->employee_id = $employee_id;
    }

    public function passes($attribute, $value)
    {
        $timesloteValue = Carbon::createFromFormat('d-m-Y H:i', $value);
        $employee = Employee::find($this->employee_id);

        // perform checks: this part works, but requires the employee instance

       return true;
    }
} 

Then in the rules, you pass in the ID,

public function rules()
{
  return [
    'employee_id' => ['required', 'numeric'],
    'timeslot' => ['required', new TimeSlotEmployeeRule($this->employee_id)],
  ];
}