Outpot - пустой массив. Почему .. ??? Codeigniter api для выборки подкатегорий на основе категорий

Question

Код контроллера:

public function getSubcategory_post(){
    $subcat = array();
    $category = $this->input->post('category');
  // echo $category;
    if($category){
        $con['conditions'] = array('category'=>$category);

        $subcat = $this->dropdown->getSubcategoryRows($con);
    }
    echo json_encode($subcat);
}

Код модели:

function getSubcategoryRows($params = array()){
   $this->db->select('sub_category.sub_category_id, sub_category.sub_category_name');
   // $this->db->from($this->subcatTbl.' as s');
    //$this->db->select("*");
    $this->db->from("sub_category");
    //fetch data by conditions

    //fetch data by conditions
    if(array_key_exists("conditions",$params)){
        foreach ($params['conditions'] as $key => $value) {
            if(strpos($key,'.') !== false){
                $this->db->where($key,$value);
            }else{
                $this->db->where('sub_category.'.$key,$value);
            }
        }
    }

    $query = $this->db->get();
    $result = ($query->num_rows() > 0)?$query->result_array():FALSE;

    //return fetched data
    return $result;
}