In Laravel, custom validation rules can be implemented in three ways. 1. Use Rule::make to create closure verification rules, suitable for simple logic, such as checking whether the mailbox has been registered; 2. Create reusable rule classes, generate and implement the validate method through the Artisan command, suitable for large projects or multiple reused logic; 3. Centrally manage verification rules and prompt information in form requests to improve structural clarity and maintenance. In addition, error prompts can be customized by using the $fail() or overridden messages() method. These methods effectively enhance the readability and maintainability of verification logic.

In Laravel, custom validation rules are a very practical feature, especially when dealing with complex business logic. Laravel provides flexible mechanisms to extend the default verification system, allowing you to add your own rules as needed.

1. Create custom rules using Rule::make

The easiest way is to create a closure using Rule::make method to execute the verification logic. For example:

 use Illuminate\Validation\Rule;

$rules = [
    'email' => [
        'required',
        'email',
        Rule::make(function ($attribute, $value, $fail) {
            if (User::where('email', $value)->exists()) {
                $fail('This email address has been registered');
            }
        }),
    ],
];

This method is suitable for simple verification logic and can be embedded directly into the form request or the controller. But if you have many similar rules or want to reuse some verification logic, it is recommended to further encapsulate.

2. Create reusable rule classes (Custom Rule Objects)

Laravel supports the generation of custom rule classes through the Artisan command:

 php artisan make:rule UniqueEmailForUsers

This command will generate a rule class file in the app/Rules directory. You can implement the __invoke method in it:

 namespace App\Rules;

use Closure;
use Illuminate\Contracts\Validation\ValidationRule;

class UniqueEmailForUsers implements ValidationRule
{
    public function validate(string $attribute, mixed $value, Closure $fail): void
    {
        if (User::where('email', $value)->exists()) {
            $fail('This email address has been used');
        }
    }
}

Then use it like this in your verification rules:

 use App\Rules\UniqueEmailForUsers;

'email' => ['required', 'email', new UniqueEmailForUsers()]

This approach is more suitable for large projects or verification logic that requires multiple reuses.

3. Organize rules in form requests

If you often process a certain type of request (such as user registration and product listing), it is recommended to use Form Request to centrally manage verification logic.

Generate a form request:

 php artisan make:request StoreUserRequest

Open the generated class and introduce the rule object you defined earlier in rules() method:

 public function rules()
{
    Return [
        'email' => ['required', 'email', new UniqueEmailForUsers()],
        'password' => 'required|min:8',
    ];
}

This not only has a clear structure, but also facilitates post-maintenance and testing.

Tips: Prompt information can also be customized

No matter which way you define the rule, you can specify the error prompt by returning the string:

• Call $fail('提示信息') in Rule::make
• Call $fail->('提示信息')
• Or override messages() method in the form request to customize the field prompt

for example:

 public function messages()
{
    Return [
        'email.required' => 'The email cannot be empty',
        'password.min' => 'Password is at least 8 digits',
    ];
}

Basically that's it. Using these methods reasonably can make your Laravel verification logic clearer and easier to maintain.

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