Laravel UpdateUserRequest validation rule with user id

I have a User model, and this is my update() method in UserController:

public function update(Request $request, User $user)
{
    // Assign authorization
    Gate::authorize('update', $user);
    
    $request->validate([
        'username' => 'required|unique:users,username,' . $user->id,
        // other rules ...
    ]);
    
    // ...
}

I want to keep these validation rules in a separate UpdateUserRequest request:

class UpdateUserRequest extends FormRequest
{
    public function authorize(): bool
    {
        return true; // Changed to 'true' to handle authorization logic in UserPolicy
    }

    public function rules(): array
    {
        return [
            'username' => 'required|unique:users,username,' . $user->id, // <-- Problem
            // other rules ...
        ];
    }
}

The problem here is that $user is not defined. I have read elsewhere that using a route for this matter is a possible solution, but that's not the proper way of achieving this task.

My question is what is the correct way to pass user information to UpdateUserRequest class?

My question is what is the correct way to pass user information to UpdateUserRequest class?

I assumed you are using laravel 11.X and your route definition is...

Route::put('/users/{user}', [UserController::class, 'update']);

In this scenario you can do it inside the UpdateUserRequest.

class UpdateUserRequest extends FormRequest
{
    public function authorize(): bool
    {
        // Here you can also interact with your `gates` & `policy`,Check the docs link I provided below to get clear insights.
        return true; 
    }

    public function rules(): array
    {
        //Scenario 1
        $user = User::find($this->route('user')); //If you are not using `implicit model binding`
        //Scenario 2
        $user = $this->user ; //If you are using `route-model-binding`


        return [
            'username' => 'required|unique:users,username,' . $user->id, // <-- "Issue will be solved"
            // other rules ...
        ];
    }
}

Then in Controller class import & type-hint the FormRequest class i.e. UpdateUserRequest on your Controller method that is missing in your current code.

public function update(UpdateUserRequest $request, User $user)
{
    // Assign authorization
    Gate::authorize('update', $user);

    // Retrieve the validated input data...
     $validated = $request->validated();  // it will by default validate all the input data you set up in the `rule()` of `UpdateUserRequest`
    
    
    // ...
}

For more clear and in-depth insights please check the official-docs here.