Inheritance in CodeIgniter
check if the class has already been initialized like this:
if (!class_exists('classname')){ // ok fine create new instance now}
Possibly when you $this->load->model('Form'), you manually included the models/form.php file?
In your leaveform.php model file, make sure you load the superclass model you extend using codeigniter's model loading mechanism instead of require or include. Codeigniter has a loader that keeps track of already-loaded files to avoid redeclaring classes, but you need to use $this->load to use it. It won't know about files loaded directly with include or require.
So at the top of leaveform.php, use this:
$CI =& get_instance(); $CI->load->model('Form');This is not related, but you will have pain unless you namespace your CodeIgniter model classes the same way you namespace Controller classes.
Try using FormModel extends CI_Model {}; Instead of Form extends CI_Model {};