send to model on update_city function get error city is already exist

abhijeet

I am do this then solve error have any other way
`public function insert_city()
{
$city_id = $this->input->post('city_id');

        $this->load->library('form_validation');
        $this->form_validation->set_rules('city', 'City', 'required|is_unique[city_table.city]', array('is_unique' => 'City already exist.'));
        if ($this->form_validation->run()) {
            if ($this->input->post()) {
                $state_id = $this->input->post('state_id');
                $city = $this->input->post('city');
                $city_meta_title = $this->input->post('city_meta_title');
                $city_meta_description = $this->input->post('city_meta_description');
            }
            $data = array('state_id' => $state_id, 'city' => $city,'city_meta_title'=>$city_meta_title,'city_meta_description'=>$city_meta_description);
            $this->load->model('Action_Model');
                $this->Action_Model->insert_city($data);
        }
        else {
               $this->load->view('admin/add-city');
           }



             if($city_id){
                if ($this->input->post()) {
                    $state_id = $this->input->post('state_id');
                    $city = $this->input->post('city');
                    $city_meta_title = $this->input->post('city_meta_title');
                    $city_meta_description = $this->input->post('city_meta_description');
                }

            $data = array('state_id' => $state_id, 'city' => $city,'city_meta_title'=>$city_meta_title,'city_meta_description'=>$city_meta_description);


        $this->load->model('Action_Model');
        $this->Action_Model->update_city($data, $city_id);
    }`