How to change tabs via a button within another tab? - KivyMD

I just started coding and I'm doing a test app, but I can't change tabs when I click the button. I needed to check if something was written in the text input, if the date was selected, and if these two options are correct, I wanted the "CalculaCompra" tab to open when clicking the button. Can anyone help me with this? I've been racking my brain for two days with this... kkkkk

Python code

from kivymd.app import MDApp
from kivymd.uix.floatlayout import MDFloatLayout
from kivymd.uix.picker import MDDatePicker
from kivymd.uix.tab import MDTabsBase, MDTabs
from datetime import datetime
from locale import setlocale, LC_ALL
import sqlite3


class VamosComprar(MDApp):
    def build(self):
        pass

    def on_start(self):
        self.root.ids.tabs.add_widget(MenuApp(tab_label_text='Inicio'))
        self.root.ids.tabs.add_widget(CalculaCompra(tab_label_text='Calculadora'))
        self.root.ids.tabs.add_widget(VerListaCompra(tab_label_text='Listas'))

    def on_tab_switch(self, instance_tabs, instance_tab, instance_tab_label, tab_text):
        pass

    def irpracalcula(self):
        self.on_tab_switch = CalculaCompra(tab_label_text='Calculadora')
        self.on_tab_switch.to_widget()

    # def irpracalcula(self, tacerto=False):
    #     # verif = MenuApp()
    #     # verif.criarLista()
    #     self.tacerto = tacerto
    #     try:
    #         if self.tacerto:
    #             self.root.ids.tabs.on_tab_switch(tab_label_text='Calculadora')
    #     except Exception as erro:
    #         print(erro)


class MenuApp(MDFloatLayout, MDTabsBase):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)

    def criarLista(self):
        self.nomedalista = self.ids.nomedalista.text
        self.ondevaicomprar = self.ids.ondevaicomprar.text
        self.datalabel = self.ids.datamenu.text
        if len(self.nomedalista) <= 0:
            self.ids.nomedalista.error = True
            self.ids.nomedalista.text = ' '
        if self.datalabel == 'Insira a data':
            self.ids.datamenu.theme_text_color = 'Error'
        if len(self.nomedalista) > 0 and self.datalabel != 'Insira a data':
            self.abas = MDTabs()
            self.abas.ids.tabs.switch_tab(CalculaCompra)

            # ircalc = VamosComprar()
            # ircalc.irpracalcula(tacerto=True)

            # try:
            #     self.nomedalistadb = self.nomedalista.replace(" ", "_")
            #     banco = sqlite3.connect('listComp.db')
            #     cursor = banco.cursor()
            #     cursor.execute('CREATE TABLE IF NOT EXISTS ' + self.nomedalistadb + ' ('
            #                                                              'id INTEGER PRIMARY KEY AUTOINCREMENT,'
            #                                                              'mercado TEXT,'
            #                                                              'data TEXT,'
            #                                                              'produto TEXT,'
            #                                                              'quantidade REAL,'
            #                                                              'precounit REAL,'
            #                                                              'qtdatac REAL,'
            #                                                              'precoatac REAL,'
            #                                                              'total REAL'
            #                                                              ')')
            #
            #     banco.close()
            #     return print('Feito tudo certo')
            # except sqlite3.Error as erro:
            #     print(f'Erro: {erro}')


    def abrir_data(self):
        setlocale(LC_ALL, 'pt_BR.utf-8')
        date_dialog = MDDatePicker()
        date_dialog.bind(on_save=self.on_save, on_cancel=self.on_cancel)
        date_dialog.open()

    # Quando salvar data muda na label
    def on_save(self, instance, value, date_range):
        # print(instance, type(value), date_range, type(str(value)))
        self.dtlabelpos = f'{str(value.day)}/{str(value.month)}/{str(value.year)}'
        self.ids.datamenu.text = self.dtlabelpos


    def on_cancel(self, instance, value):
        pass

class CalculaCompra(MDFloatLayout, MDTabsBase):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)

class VerListaCompra(MDFloatLayout, MDTabsBase):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)


VamosComprar().run()

Code Kivy:

MDBoxLayout:
    orientation: 'vertical'

    MDToolbar:
        title: 'Vamos Comprar?'
        anchor_title: 'center'

    MDTabs:
        id: tabs
        tab_hint_x: True
        on_tab_switch: app.on_tab_switch(*args)

<MenuApp>
    id: menuapp
    MDBoxLayout:
        padding: 40, 40, 40, 40
        margin: 40, 40
        orientation: 'vertical'

        MDLabel:
            id: titulomenu
            text: "Criar lista de Compras"
            halign: "center"
            font_size: 24

        MDTextField:
            id: nomedalista
            hint_text: "Nome da Lista"
            required: True
            helper_text_mode: "on_error"
            helper_text: 'Insira um nome para a lista'

        MDTextField:
            id: ondevaicomprar
            hint_text: "Onde irá fazer a compra?"

        MDBoxLayout:
            padding: 50, 50

            MDLabel:
                id: datamenu
                index: 0
                text: "Insira a data"
                valign: 'middle'

            MDIconButton:
                index: 1
                icon: 'calendar-month-outline'
                valign: 'middle'
                on_release: root.abrir_data()

        MDRaisedButton
            id: btncriarlista
            text: 'Criar Lista'
            size_hint_x: .8
            pos_hint: {"center_x": .5, "center_y": .5}
            on_release: root.criarLista()



<CalculaCompra>
    id: calculacompra
    MDBoxLayout:
        padding: 40, 40, 40, 40
        margin: 40, 40
        orientation: 'vertical'

        MDLabel:
            id: titulocalcula
            text: "Preencha os campos"
            halign: "center"
            font_size: 24

        MDTextField:
            id: produto
            hint_text: "Produto"
            required: True
            helper_text_mode: "on_error"
            helper_text: 'Insira o nome do produto'

        MDTextField:
            id: quantidade
            hint_text: "Quantidade"

        MDTextField:
            id: precounit
            hint_text: "Preço unit."

        MDBoxLayout:
            padding: 50, 50

            MDLabel:
                id: total
                index: 0
                text: "Total"
                valign: 'middle'

            MDIconButton:
                index: 1
                icon: 'cart-plus'
                valign: 'middle'
                on_release:

        MDRaisedButton
            text: 'Ver Lista'
            size_hint_x: .8
            pos_hint: {"center_x": .5, "center_y": .5}
            on_release:

<VerListaCompra>

    MDLabel:
        id: label
        text: "ver lista"
        halign: "center"

I wanted that when I click on the button, it would check if there is something written in the text and if the date was selected, and when I click on the button, go to the next tab.