php 49 lines · 7 steps

How a custom coupon rule validates in Laravel

A Laravel validation rule checks a coupon code against existence, status, expiry, limits, and per-user reuse.

Explained by highlit

Laravel Intermediate validation eloquent business-rules guard-clauses

1<?php
2 
3namespace App\Rules;
4 
5use App\Models\Coupon;
6use Closure;
7use Illuminate\Contracts\Validation\ValidationRule;
8 
9class Redeemable implements ValidationRule
10{
11    public function __construct(protected ?int $userId = null)
12    {
13    }
14 
15    public function validate(string $attribute, mixed $value, Closure $fail): void
16    {
17        $coupon = Coupon::whereRaw('LOWER(code) = ?', [strtolower($value)])->first();
18 
19        if (! $coupon) {
20            $fail('The :attribute is not a valid coupon.')->translate();
21 
22            return;
23        }
24 
25        if (! $coupon->is_active) {
26            $fail('This coupon is no longer active.');
27 
28            return;
29        }
30 
31        if ($coupon->expires_at !== null && $coupon->expires_at->isPast()) {
32            $fail('This coupon expired on :date.')->translate([
33                'date' => $coupon->expires_at->toFormattedDateString(),
34            ]);
35 
36            return;
37        }
38 
39        if ($coupon->max_redemptions !== null && $coupon->redemptions_count >= $coupon->max_redemptions) {
40            $fail('This coupon has reached its redemption limit.');
41 
42            return;
43        }
44 
45        if ($this->userId !== null && $coupon->redemptions()->where('user_id', $this->userId)->exists()) {
46            $fail('You have already redeemed this coupon.');
47        }
48    }
49}

01 / 01

STEP 01

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Three takeaways

1Custom rule objects let you encapsulate multi-step business logic behind Laravel's validation pipeline.
2Sequential guard clauses that each fail-and-return keep complex validation readable and short-circuited.
3Constructor parameters let a rule carry context, like the current user, into its checks.

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