Include extra validation in Laravel 8 using $errors Variable

I have a store Method for my TransactionController, at the moment it does validate that the required information is received (standard Laravel validation), nonetheless, it can’t check if the value received exists on a third table (since it’s a foreign key).

Store method of TransactionController.php

public function store(Request $request)
    {

        $request -> validate([
            
            'folio' => 'required',
            'codigo_referido_id' => 'required',
            'descuento_activo_id' => 'required',
            'lead_id' => 'required'

        ]);

    }

[...]

I want to add further validation to ensure that the information received is ready for get stored in the database and if it is not, inform the user with a custom message.

This is done with:

TransactionController.php store Method

[...]
if($request['codigo_referido_id']){
            
            if( Empleado::find($request['codigo_referido_id']) ){

                // Continue to the next validation

            }else{

                // return to view with the error message [I want to use the default $errors variable to store the error return].

            }
        
        

        }

How can I return back to the view sending my custom error message in the else clause?

Answer

You can add custom validation for this instead of if else

$request -> validate([

            'folio' => 'required',
            'codigo_referido_id' => ['required', function ($attribute, $value, $fail) {
                if (!Empleado::find($value)) {
                    $fail('The '.$attribute.' is invalid.');
                }
            }],
            'descuento_activo_id' => 'required',
            'lead_id' => 'required'

        ]);

Ref:https://laravel.com/docs/8.x/validation#custom-validation-rules