Prevent duplicate entry at insert and update using codeigniter - codeigniter

Question

I am trying to stop duplicate entry in database using codeigniter. It works fine when I insert data but when I update the data it is not working.. If I am change only description not departmentname it give already exist message.
For that I am using bellow code in my controller:
$this->form_validation->set_rules('departmentname', 'Departmentname', 'trim|required|xss_clean|is_unique[department_master.departmentname]');

Answer 1

You have to write your validation code.
Method 1: Validation Callback
Your rule declaration:
$this->form_validation->set_rules('field', 'label', 'callback__is_unique2');
The method, in the same controller that the validation:
public function _is_unique2($input) {
$exclude_id = $this->input->post('id');
if( $this->db->where('departmentname', $input)->where('id !=', $exclude_id)
->limit(1)->get('department_master')->num_rows())
{
$this->form_validation->set_message('_is_unique2', 'name exists');
return FALSE;
}
return TRUE;
}
Callbacks: Your own Validation Functions
Method 2: Extend Form_validation to add a new validation rule
Your rule declaration:
$exlclude_id = $this->input->post('id');
$this->form_validation->set_rules('field', 'label',
'is_unique2[department_master.departmentname.id_field.'.$exclude_id.']');
The extend of Form_validation,
//Libraries/MY_Form_validation.php
class MY_Form_validation extends CI_Form_validation {
public function __construct() {
parent::__construct();
}
public function is_unique2($str, $field)
{
list($table, $field, $exclude_field, $exclude_value)=explode('.', $field);
return (bool) $this->CI->db
->where($field, $str)
->where($exclude_field.' !=', $exclude_value)
->limit(1)
->get($table)->num_rows();
}
}
Extending Native Libraries
*No tested code

Answer 2

You can use callback function in validation rules. For example
$this->form_validation->set_rules('departmentname', 'Departmentname', 'trim|required|xss_clean|is_unique[department_master.departmentname]|**callback_is_unique_department**');
Callback function take first argument in a function is field value itself.
public function is_unique_department($dep_name)
{
// select query which find same department value exists or not if exists then write
$this->form_validation->set_message('is_unique_department', 'This Department Name is already exists.');
return false;
else write return false
}