How to fix the error validation check account?

i made the login, the rules if the login true, the login will enter to next form, if another one input true show nottification "username and password not valid, and if all input false back to form login. the error said in form 31 but i think the syntax are correct, what's wrong about the syntax ?

this is codeigniter 3.10 and PHP 7, line 31 in syntax $num_account = count($temp_account);

this is the controller

 public function login()
    {
        $username = $this->input->post('username','true');
        $password = $this->input->post('password','true');
        $temp_account = $this->user_model->check_user_account($username,$password)->row();
        //check account
        $num_account = count($temp_account);
        $this->form_validation->set_rules('username','Username','required');
        $this->form_validation->set_rules('password','Password','required');
        if($this->form_validation->run()==FALSE)
        {
            $this->load->view('account/form_login');
        }
        else {
            if ($num_account > 0) {
                //kalau ada set session
                $array_items = array(
                    'id_user' => $temp_account->id_user,
                    'username' => $temp_account->username,
                    'logged_in' => true
                );
                $this->session->set_userdata($array_items);
                redirect(site_url('account/view_success_page'));
            } else {
                //kalau ga ada diredirect lagi ke halaman login
                $this->session->set_flashdata('notification', 'Peringatan : Username dan Password tidak cocok');
                redirect(site_url('account'));
            }
        }
    }

Message: count(): Parameter must be an array or an object that implements Countable Filename: controllers/account.php Line Number: 31

Method:

function check_user_account($username,$password) { 
    $this->db->select('*'); 
    $this->db->from('user'); 
    $this->db->where('username',$username); 
    $this->db->where('password',$password); 
    return $this->db->get(); 
}