Count function brings different amount according to date parameters passed

Question

I need to take the month and the year twice: to consult the expenses and calculate the amount of expenses found.

In the function consultarDespesas, step for the two global variables to subsequently access them in the function quantidadeDespesas. The $this->request->data['Despesa']['ano'] e $this->request->data['Despesa']['mes'] stay null. I don’t know how to access anywhere in the controller Expenses this requisition.

So I chose to take the month and year soon, but still the two global variables are null when the program arrives at function quantidadeDespesas.

Already debugged the two global variables or attributes, already debugged $this->request->data and $this->data, but it’s no use, everything is null. Let’s see the codes:

class DespesasController extends AppController {

public $helpers=array('Form', 'Html');

public $ano;
public $mes;

public $uses = array('Despesa', 'Receita');

function to search for expenses:

public function consultarDespesa() {
    if ($this->request->is('post')) {
            $this->ano = $this->data['Despesa']['ano'];
            $this->mes = $this->data['Despesa']['mes'];

            $despesas = $this->Despesa->find('all',
            array(
    'conditions'=>array(
    'YEAR(data_despesa)'=>$this->request->data['Despesa']['ano'],
    'MONTH(data_despesa)'=>$this->request->data['Despesa']['mes'])));

            if ($despesas == null) {
                $this->Session->setFlash("Sua pesquisa não retornou nenhum resultado.");
            }

            else {
                $this->Session->write("Despesas", $despesas);

                $this->quantidadeDespesas();
                $this->redirect(array('action'=>'exibirDespesas'));
            } 
    }
}   

Function to count how many expenses incurred:

public function quantidadeDespesas() {
    $quantidadeDespesas = $this->Despesa->query("select count(id_despesa) as quantidadeDespesas from despesas where year(data_despesa)='$this->ano' and MONTH(data_despesa)='$this->mes'");

    return $quantidadeDespesas;
}