Kivy - 如何在不同文件中分屏？

Question

i have problem with including kv file to another one. I wanna have separate files for each screen and include them in 'main.kv', but i have a problem with accesign id/components from splitted file.

See error:

File "screen_home.kv", line 9, in left_action_items: [['menu', lambda x: nav_drawer.set_state("open")]] NameError: name 'nav_drawer' is not defined

See included files:

main.py

from kivymd.app import MDApp
from kivy.lang import Builder
from kivy.uix.boxlayout import BoxLayout


class ContentNavigationDrawer(BoxLayout):
    pass


class mainApp(MDApp):
    title = "mainApp"
    app_name = title

    def build(self):
        return Builder.load_file("main.kv")


if __name__ == "__main__":
    mainApp().run()

main.kv

#:include screen_home.kv

<ContentNavigationDrawer>:
    orientation: "vertical"
    padding: "8dp"
    spacing: "8dp"
    AnchorLayout:
        anchor_x: "center"
        size_hint_y: None
        height: app_logo.height
        Image:
            id: app_logo
            size_hint: None, None
            size: "80dp", "80dp"
            source: "./res/images/logo.png"
    MDLabel:
        text: app.app_name
        halign: "center"
        font_style: "Subtitle2"
        size_hint_y: None
        height: self.texture_size[1]
    ScrollView:
        MDList:
            OneLineAvatarIconListItem:
                text: "Home"
                on_press:
                    root.nav_drawer.set_state("close")
                    root.screen_manager.current = "screen_home"
                IconLeftWidget:
                    icon: "home"
                    valign: 'center'

            OneLineAvatarIconListItem:
                text: "Screen 1"
                on_press:
                    root.nav_drawer.set_state("close")
                    root.screen_manager.current = "screen_1"
                IconLeftWidget:
                    icon: "scatter-plot"

Screen:
    NavigationLayout:
        ScreenManager:
            id: screen_manager
            ScreenHome:
            Screen:
                name: "screen_1"
                BoxLayout:
                    orientation: 'vertical'

                    MDToolbar:
                        title: "First Screen"
                        elevation: 10
                        left_action_items: [['menu', lambda x : nav_drawer.set_state("open")]]

                    BoxLayout:
                        orientation: 'horizontal'
                        MDLabel:
                            halign: "center"
                            valign: "center"
                            text: "Label on screen_1"

        MDNavigationDrawer:
            id: nav_drawer

            ContentNavigationDrawer:
                screen_manager: screen_manager
                nav_drawer: nav_drawer

screen_home.kv

<ScreenHome@Screen>:
    name: "screen_home"
    BoxLayout:
        orientation: 'vertical'

        MDToolbar:
            title: "Home"
            elevation: 10
            left_action_items: [['menu', lambda x: nav_drawer.set_state("open")]]
        Widget:
            canvas:
                Color:
                    rgb: 0, 1, 0
                Rectangle:
                    size: (800,200)
        Widget:
            MDLabel:
                text: "Home screeen"
                size: root.width, root.height
                halign: 'center'
                valign: 'center'

Answer 1

So I am not 100% sure as I am dealing with this same issue. I am able to build the app correctly using a single "main.py" file where the kivyMD language is built in the same file. But when I am moving into a design.kv file, I am having difficulty building the widget tree correctly to access the more complex widgets.

I believe you must create a widget, as in MDScreen, to be the appliations main widget. Then, you must add the complex widgets which you are choosing to use, IE MDNavigationDrawer. Then further adding to the widgets, you add the screenmanager and then the individual screens.

I am still seeking advice and trying to get this to work but I hope that helps. If you have moved forward with your project and this issue please feel free to post.