Sometimes Trying to get property of non-object - php

Question

After login after some random time when i refresh any page on website, sometimes it works perfectly, but sometimes it shows error like Trying to get propert on different lines of model and controller file.
For example, when i refresh the page error was shown in below function of model named user_model and controller named User.php:
User_model.php:
public function get_client_id($email)
{
$this->db->select('id');
$this->db->where('email', $email);
$query = $this->db->get('crm_accounts');
$result = $query->row();
return $result->id; //line 135
}
Users.php:
$email = $_SESSION['email'];
$id = $this->user_model->get_client_id($email); //line 145
Setting the session value after login:
$email = $this->input->post("email");
$password = $this->input->post("pass");
$result = $this->user_model->login($email, $password);
if ($result == TRUE)
{
$this->session->set_userdata('email',$email);
$this->session->set_userdata('logged_in',TRUE);
$data = $this->user_model->get_username($email);
$this->session->set_userdata('data', $data);
redirect('admin_view');
}
else
{
$this->load->view('all_field');
}
code for deleting the session after logout:
$logged_in = $this->session->userdata('logged_in');
$log = $this->session->userdata('email');
if($logged_in || (!empty($log)))
{
$array_item = array('email', 'logged_in');
$this->session->unset_userdata($array_item);
redirect('');
}
else
{
$this->load->view('error_page');
}
Here, i got error on like
Tring to get property of non-object on line 135 of user_model.php and in backtrace it found error on Users.php on line 145
I have noticed that when i get this type of error in model, i am getting data in that particular method using session variable $email in which the session data is stored. But i have put such condition in controller:
public function index()
{
if(!empty($_SESSION['email']))
{
$email = $_SESSION['email'];
$data = $this->user_model->get_username($email);
$this->session->set_userdata('data',$data);
redirect('clientview');
//echo "You are already logged in";
}
else
{
$this->load->view('signup');
}
}
So, if the value of session variable $email is not set than it should go on signup page.
So, i am not getting what is actually problem. Because sometimes it works perfectly and sometimes not. Once if i get such error, i have to clear my history and than i have to log in again.

Answer 1

In Codeigniter you have a specific way to get form or set values in the session.
If you want to check if the session exist you need to do
$this->session->userdata('email');
Which will retrieve the stored value.
And as you already do:
$this->session->set_userdata('email', $email);
To set a value in the session.
Additionally when the user is logging out yoi need to reset the stored value, ptherwise it will never be empty.
$this->session->set_userdata('email', '');
NOTE: What you are doing is of course not the best way to do such kind of stuff, as a login and logout system. I suppose you are just learning and you are doing this not for a production application.
If you do, please try to use ionAuth authentication library for Codeigniter, that you can find here:
http://benedmunds.com/ion_auth/
And follow some tutorial about it:
http://www.tutorials.kode-blog.com/codeigniter-authentication
Just keep in mind that user authentication is a serious security matter so be carefull.