Not receiving any validation error on view page

My application runs on the latest version of CI, but somehow I am not getting any validation error on my view page.
view page code:-

Code:

<form method="POST" action="<?= site_url('service-providers'); ?>" accept-charset="UTF-8">
   <?= view('AdminProfile\Views\_notifications') ?>
                        <div class="form-group">
                            <label for="email">Email <span class="mandet">*</span></label>
                            <input type="text" class="form-control" name="email" id="email" value="<?= old('email') ?>" placeholder="Enter Email">
                            <span class="text-danger"><?= $validation->showError('email'); ?></span>
                        </div>
                        <div class="form-row">
                            <div class="form-group col-md-12">
                                <label for="password">Password <span class="mandet">*</span></label>
                                <input type="password" class="form-control" name="password" id="password" placeholder="Enter Password">
                                <span class="text-danger"><?= $validation->showError('password'); ?></span>
                            </div>
                        </div>
                        <?= csrf_field(); ?>
                        <button class="btn btn-outline-success my-2 my-sm-0  login-btn" type="submit">Login</button>
                    </form>

and this is the code of the controller

PHP Code:

public function attemptLogin()
 {
 $rules = [
 'email' => 'required',
 'password' => 'required|min_length[8]',
 ];

 if (! $this->validate($rules)) {
 return redirect()->back()->withInput();
 }
} 


on the controller, I can print the error but on the view page, it is coming blank.

Learning Codeigniter 

Read https://codeigniter4.github.io/CodeIgnit...ion-errors

ci-phpunit-test | CodeIgniter Testing Guide | CodeIgniter 3 to 4 Upgrade Helper

Read https://codeigniter4.github.io/CodeIgnit...ion-errors

I tried, but I am not getting my old input value as well as any errors, although I am using return redirect()->back()->withInput();

---

fixed it, thanks for the resource.

this was helpful https://github.com/kenjis/ci4-validation.../form2.php

Learning Codeigniter 

What was the issue?

ci-phpunit-test | CodeIgniter Testing Guide | CodeIgniter 3 to 4 Upgrade Helper

What was the issue?

Instead of using set_value() and show_validation_error(), I was using old() and $validation->getError(). It was foolish of me I did not read the documentation properly. validation_show_error

Learning Codeigniter