what am I doing wrong with form_validation messages name field access? - codeigniter

Question

I want to try to valid confirm password matches with my confirm password, but it not then it will show me an error , but when I try to set up my messages for username then show me it cannot be accessed by it what am I doing wrong? but I try to change name filed in my username , but it doesn't work.
new_user controller
public function new_user(){
$first_name = $this->security->xss_clean(strip_tags($this->input->post('first_name')));
$last_name = $this->security->xss_clean(strip_tags($this->input->post('last_name')));
$profile_id = $this->security->xss_clean(strip_tags($this->input->post('profile_id')));
$password = $this->security->xss_clean(strip_tags($this->input->post('password')));
$username = $this->security->xss_clean(strip_tags($this->input->post('username')));
$data = array(
'first_name' => $first_name,
'last_name' => $last_name,
'profile_id' => $profile_id,
'password' => password_hash($password, PASSWORD_BCRYPT),
'username' => $username,
);
$this->form_validation->set_rules('first_name','first_name','trim|required');
$this->form_validation->set_rules('last_name','last_name','trim|required');
$this->form_validation->set_rules('username','username','trim|required|');
$this->form_validation->set_rules('password', 'password', 'trim|required');
$this->form_validation->set_rules('conf_password', 'conf_password', 'matches[password]|required');
$this->form_validation->set_message('first_name', 'Please enter First Name');
$this->form_validation->set_message('last_name', 'Please enter Last Name');
$this->form_validation->set_message('username', 'Please enter Username');
$this->form_validation->set_message('password', 'Please enter Password');
if ($this->form_validation->run() == FALSE) {
$this->json($this->form_validation->error_array());
}else{
$this->user->signup($data);
}
}
form
<form id="signup" method="post" onsubmit="return false;">
<h2 class="sr-only">New User</h2>
<div class="illustration">
<i class="icon ion-ios-locked-outline" style="color: rgb(251, 244, 244);"></i>
</div>
<div class="form-group">
<input type="text" name="first_name" id="first_name" placeholder="First Name" class="form-control"
required="required" />
</div>
<div class="form-group">
<input type="text" name="last_name" id="last_name" placeholder="Last Name" class="form-control"
required="required" />
</div>
<div class="form-group">
<select name="profile_id" id="profile_id" class="form-control" required="required">
<option value="">Select a Profile</option>
<?php foreach ($profile as $value): ?>
<option value="<?php echo $value['id'];?>">
<?php echo $value['profile']; ?>
</option>
<?php endforeach ?>
</select>
</div>
<div class="form-group">
<input type="text" name="username" id="username" placeholder="username" class="form-control"
required="required" />
</div>
<div class="form-group">
<input type="password" name="password" id="password" placeholder="***********" class="form-control"
required="required" />
</div>
<div class="form-group">
<input type="password" name="conf_password" id="conf_password" placeholder="***********" class="form-control"
required="required" />
</div>
<div class="form-group">
<button class="btn btn-primary btn-block" type="submit" style="background-color: rgb(41, 54, 78);">Ingresar</button>
</div>
</form>
output error
{username: "Unable to access an error message corresponding to your field name username.()"}
username
:
"Unable to access an error message corresponding to your field name username.()"

Answer 1

I think you should
Replace this
$this->form_validation->set_rules('username','username','trim|required|');
To:
$this->form_validation->set_rules('username','username','trim|required');