在 MDTab 中显示来自 API 请求的数据

Question

我正在尝试使用 Python 学习编码，并且我正在制作一个应用程序来跟踪使用 KivyMD 的用户的会话时间。目前，我正在尝试通过从我的数据库调用 api 获取 json 数据来显示总时间。我编写了一个函数来获取和处理 json 数据以计算总时间。当 Mijn sessie 选项卡加载时，该函数必须自动触发以在 MDLabel time_label 中显示数据（变量：total_minutes）。这是我很困惑的地方。

我在 Kivy 中找到了 on_pre_enter 函数，它会在屏幕加载时触发该函数，但它只适用于 Screen Class 而不是 Tabs Class。如果我在 Screen class 中执行 python 逻辑，我不知道如何在 Tabs class 中使用 python 变量。我用 Objectproperty 和 Stringproperty 尝试了很多东西，但 none 成功了。我想我在这里遗漏了一些更大的东西。

我将 post 代码让您在亲眼看到该应用程序时更加清楚。出于安全原因，我用一个产生相同结果（浮动）的小函数替换了 api 请求函数。

非常感谢！

main.py 文件

from kivymd.app import MDApp
from kivy.lang import Builder
from kivy.core.window import Window
from kivy.uix.screenmanager import ScreenManager, Screen
from kivymd.uix.tab import MDTabsBase
from kivymd.font_definitions import fonts
from kivymd.icon_definitions import md_icons
from kivy.uix.floatlayout import FloatLayout
from kivy.properties import ObjectProperty, StringProperty
from kivy.uix.widget import Widget
from kivymd.uix.label import MDLabel
import requests
import json
from datetime import datetime

Window.size = (300, 500) # voor develop doeleinden mobielscherm

class Screen1(Screen):
    pass

    def on_pre_enter(self, *args):

        def func(a, b):
            total_minutes = a - b
            return total_minutes

        print(func(3000,1500))

class Screen2(Screen):
    pass


class Screen3(Screen):
    pass


class Screen4(Screen):
    pass


class Tab_mijn_sessie(FloatLayout, MDTabsBase):
    pass


class Tab_alarm(FloatLayout, MDTabsBase):
    pass


class Tab_actieve_drinkers(FloatLayout, MDTabsBase):
    pass


class Tab_score(FloatLayout, MDTabsBase):
    pass


class Tab_achievments(FloatLayout, MDTabsBase):
    pass


class Tab_historie(FloatLayout, MDTabsBase):
    pass


class DemoApp(MDApp):

    def build(self):

        self.theme_cls.primary_palette = 'Red'
        self.theme_cls.theme_style = 'Dark'
        screen = Builder.load_file('demo_file.kv')

        return screen


DemoApp().run()

demo_file.kv 文件

Screen:

    NavigationLayout:

        ScreenManager:
            id:screen_manager

            Screen1:
                name: 'home_screen'

                BoxLayout:
                    name: 'home_layout'
                    orientation: 'vertical'

                    MDToolbar:
                        title: 'Huidige sessie'
                        left_action_items: [['menu', lambda x: nav_drawer.set_state("open")]]
                        specific_text_color: 1,1,1,1

                    MDTabs:
                        id:home_tabs
                        tab_bar_height: '35dp'
                        text_color_active: 1,1,0,1
                        text_color_normal: 0,0,0,1
                        color_indicator: 0.95, 0.95, 0.1, 1
                        tab_indicator_anim: True
                        anim_duration: 0.2
                        tab_indicator_height: '3dp'

                        Tab_mijn_sessie:
                            text: 'Mijn sessie'

                        Tab_alarm:
                            text: 'Alarm'

                        Tab_actieve_drinkers:
                            text: 'Actieve drinkers'

                    MDToolbar:
                        id: bottom_toolbar_scr1
                        name: 'bottom_toolbar'
                        specific_text_color: 1,1,1,1
                        title: '          Sessie inactief..'

            Screen2:
                name: 'statistieken_screen'

                BoxLayout:
                    name: 'statistieken_layout'
                    orientation: 'vertical'

                    MDToolbar:
                        title: 'Statistieken'
                        left_action_items: [['menu', lambda x: nav_drawer.set_state("open")]]
                        specific_text_color: 1,1,1,1

                    MDTabs:
                        id:home_tabs
                        tab_bar_height: '35dp'
                        text_color_active: 1,1,0,1
                        text_color_normal: 0,0,0,1
                        color_indicator: 0.95, 0.95, 0.1, 1
                        tab_indicator_anim: True
                        anim_duration: 0.2
                        tab_indicator_height: '3dp'

                        Tab_score:
                            text: 'Scorebord'

                        Tab_achievments:
                            text: 'Achievements'

                        Tab_historie:
                            text: 'Historie'

                    MDToolbar:
                        id: bottom_toolbar_scr2
                        name: 'bottom_toolbar'
                        specific_text_color: 1,1,1,1
                        title: '          Sessie inactief..'


            Screen3:
                name: 'logout_screen'

                BoxLayout:
                    name: 'logout_layout'
                    orientation: 'vertical'

                    MDToolbar:
                        title: 'Uitloggen'
                        left_action_items: [['menu', lambda x: nav_drawer.set_state("open")]]
                        specific_text_color: 1,1,1,1

                    Widget:


            Screen4:
                name: 'profile_screen'

                BoxLayout:
                    name: 'profile_layout'
                    orientation: 'vertical'

                    MDToolbar:
                        title: 'Profiel'
                        left_action_items: [['menu', lambda x: nav_drawer.set_state("open")]]
                        specific_text_color: 1,1,1,1

                    Widget:

                    MDToolbar:
                        id: bottom_toolbar_scr4
                        name: 'bottom_toolbar'
                        specific_text_color: 1,1,1,1
                        title: '          Sessie inactief..'

        MDNavigationDrawer:
            id:nav_drawer

            BoxLayout:
                orientation: 'vertical'
                spacing: '8dp'
                padding: '8dp'

                Image:
                    source: 'avatar.jpg'


                MDLabel:
                    text: '     Name'
                    front_style: 'Subtitle1'
                    size_hint_y: None
                    height: self.texture_size[1]

                MDLabel:

                    text: '     email@hotmail.com'
                    front_style: 'Caption'
                    size_hint_y: None
                    height: self.texture_size[1]

                ScrollView:
                    MDList:

                        OneLineIconListItem:
                            theme_text_color: 'Custom'
                            text_color: 244/255, 67/255, 54/255, 1
                            text: 'Huidige sessie'


                            on_press:
                                screen_manager.current = 'home_screen'
                                nav_drawer.set_state("close")

                            IconLeftWidget:
                                theme_text_color: 'Custom'
                                text_color: 0.95, 0.95, 0.1, 1
                                icon: 'beer'
                                on_press:
                                    screen_manager.current = 'home_screen'
                                    nav_drawer.set_state("close")

                        OneLineIconListItem:
                            theme_text_color: 'Custom'
                            text_color: 244/255, 67/255, 54/255, 1
                            text: 'Statistieken'

                            on_press:
                                screen_manager.current = 'statistieken_screen'
                                nav_drawer.set_state("close")

                            IconLeftWidget:
                                icon: 'history'
                                theme_text_color: 'Custom'
                                text_color: 0.95, 0.95, 0.1, 1
                                on_press:
                                    screen_manager.current = 'historie_screen'
                                    nav_drawer.set_state("close")

                        OneLineIconListItem:
                            theme_text_color: 'Custom'
                            text_color: 244/255, 67/255, 54/255, 1
                            text: 'Profiel'

                            on_press:
                                screen_manager.current = 'profile_screen'
                                nav_drawer.set_state("close")

                            IconLeftWidget:
                                icon: 'face-profile'
                                theme_text_color: 'Custom'
                                text_color: 0.95, 0.95, 0.1, 1
                                on_press:
                                    screen_manager.current = 'profile_screen'
                                    nav_drawer.set_state("close")

                        OneLineIconListItem:
                            theme_text_color: 'Custom'
                            text_color: 244/255, 67/255, 54/255, 1
                            text: 'Uitloggen'
                            on_press:
                                screen_manager.current = 'logout_screen'
                                nav_drawer.set_state("close")

                            IconLeftWidget:

                                icon: 'logout'
                                theme_text_color: 'Custom'
                                text_color: 0.95, 0.95, 0.1, 1
                                on_press:
                                    screen_manager.current = 'logout_screen'
                                    nav_drawer.set_state("close")

<Tab_mijn_sessie>:

    MDLabel:
        text: 'Total time'
        font_style: 'H6'
        halign: 'center'
        pos_hint: {"center_x": .5, "center_y": .4}
    MDLabel:
        id : time_label
        text: '(this has to display the total amount of time)'
        font_style: 'Body2'
        halign: 'center'
        pos_hint: {"center_x": .5, "center_y": .3}

    MDFlatButton:
        theme_text_color: 'Custom'
        text_color: 1,1,1,1
        halign: 'center'
        text:'Activate session'
        user_font_size: "48sp"
        pos_hint: {"center_x": .5, "center_y": .7}
        on_press:
            app.root.ids.bottom_toolbar_scr1.title = '          Sessie actief!'
            app.root.ids.bottom_toolbar_scr1.specific_text_color = 0,1,0,1
            app.root.ids.bottom_toolbar_scr2.title = '          Sessie actief!'
            app.root.ids.bottom_toolbar_scr2.specific_text_color = 0,1,0,1
            app.root.ids.bottom_toolbar_scr4.title = '          Sessie actief!'
            app.root.ids.bottom_toolbar_scr4.specific_text_color = 0,1,0,1


<Tab_alarm>:
    MDLabel:
        halign: 'center'
        text:'Alarm'
        user_font_size: "48sp"
        pos_hint: {"center_x": .5, "center_y": .5}


<Tab_actieve_drinkers>:
    MDLabel:
        halign: 'center'
        text:'Actieve drinkers'
        user_font_size: "48sp"
        pos_hint: {"center_x": .5, "center_y": .5}

<Tab_score>:
    MDLabel:
        halign: 'center'
        text:'Scorebord'
        user_font_size: "48sp"
        pos_hint: {"center_x": .5, "center_y": .5}

<Tab_achievments>:
    MDLabel:
        halign: 'center'
        text:'Achievments'
        user_font_size: "48sp"
        pos_hint: {"center_x": .5, "center_y": .5}

<Tab_historie>:
    FloatLayout:
        MDLabel:
            halign: 'center'
            text:'Historie'
            user_font_size: "48sp"
            pos_hint: {"center_x": .5, "center_y": .5}

        MDFlatButton:
            id: flat
            text: 'druk hier'
            pos_hint: {"center_x": .5, "center_y": 0.4}

Answer 1

from kivy.lang import Builder
from kivy.uix.floatlayout import FloatLayout

from kivymd.app import MDApp
from kivymd.uix.tab import MDTabsBase
from kivymd.icon_definitions import md_icons

KV = '''
BoxLayout:
    orientation: "vertical"

    MDToolbar:
        title: "Example Tabs"

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


<Tab>:

    MDIconButton:
        id: icon
        icon: app.icons[0]
        user_font_size: "48sp"
        pos_hint: {"center_x": .5, "center_y": .5}
'''


class Tab(FloatLayout, MDTabsBase):
    '''Class implementing content for a tab.'''


class Example(MDApp):
    icons = list(md_icons.keys())[15:30]

    def build(self):
        return Builder.load_string(KV)

    def on_start(self):
        for name_tab in self.icons:
            self.root.ids.tabs.add_widget(Tab(text=name_tab))

    def on_tab_switch(
        self, instance_tabs, instance_tab, instance_tab_label, tab_text
    ):
        '''Called when switching tabs.

        :type instance_tabs: <kivymd.uix.tab.MDTabs object>;
        :param instance_tab: <__main__.Tab object>;
        :param instance_tab_label: <kivymd.uix.tab.MDTabsLabel object>;
        :param tab_text: text or name icon of tab;
        '''

        count_icon = [k for k, v in md_icons.items() if v == tab_text]
        instance_tab.ids.icon.icon = count_icon[0]


Example().run()

https://kivymd.readthedocs.io/en/latest/components/tabs/index.html#kivymd.uix.tab.MDTabs.on_tab_switch

在 MDTab 中显示来自 API 请求的数据

Displaying data from API request in MDTab

python

kivy

kivy-language

kivymd