kivy.uix.screenmanager.ScreenManagerException： No Screen with name "login"

Question

我正在尝试使用一个过渡，以便在选择"注销";按钮-屏幕向左过渡(给人从前进到后退的感觉)。

这是一个帮助台，我正在尝试设计，我不知道为什么它返回这个错误，当我可以执行这个转换在我的导航栏的其他屏幕。

我是Kivy的新手，我的代码可能会让任何以某种方式看待这一点的人感到不安。请放心，但说真的，任何帮助都是感激的。

from kivy import Config
from kivy.app import App
from kivy.lang import Builder
from kivy.properties import StringProperty
from kivy.uix.image import Image
from kivy.uix.screenmanager import ScreenManager, Screen, FadeTransition
from kivymd.app import MDApp
from kivy.uix.boxlayout import BoxLayout
from kivymd.theming import ThemableBehavior
from kivymd.uix.navigationdrawer import MDNavigationLayout, MDNavigationDrawer
from kivymd.uix.list import MDList, OneLineAvatarListItem, ILeftBody
from kivy.properties import ObjectProperty
from kivy.uix.widget import Widget

Config.set('input', 'mouse', 'mouse,disable_multitouch')

class DrawerList(ThemableBehavior, MDList, Screen):
pass

class NavLayout(MDNavigationLayout):
pass

class Login(Screen):
nav_drawer = ObjectProperty()

class Nav(Screen):
Login = ObjectProperty()
ScreenManager = ObjectProperty

class Homepage(Screen):
Login = ObjectProperty()
nav_drawer = ObjectProperty()

class AddNewCustomer(Screen):
nav_drawer = ObjectProperty()

class AddNewStaff(Screen):
pass

class ScreenManager(ScreenManager):
Login = ObjectProperty()

class ContentNavigationDrawer(BoxLayout):
pass

class MainApp(MDApp):
def build(self):
# Window.maximize()
# self.theme_cls.theme_style = "Light"
# self.theme_cls.primary_hue = "900"
login = Builder.load_file("login.kv")
return login

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

ScreenManager:
Login:
Homepage:
AddNewCustomer:
Nav:
DrawerList:
<Login>:
name: "login"
MDCard:
size_hint: None, None
size: 700, 800
pos_hint: {"center_x": 0.5, "center_y": 0.5}
elevation: 10
padding: 25
spacing: 25
orientation: 'vertical'
Image:
source: 'images/asteria.png'
size: 100, 200
MDLabel:
id: login
font_size: 40
halign: 'center'
size_hint_y: None
height: self.texture_size[1]
padding_y: 15
MDTextFieldRound:
id: user
hint_text: "username"
icon_right: "account"
size_hint_x: None
width: 200
font_size: 18
pos_hint: {"center_x": 0.5}
MDTextFieldRound:
id: password
hint_text: "password"
icon_right: "eye-off"
size_hint_x: None
width: 200
font_size: 18
pos_hint: {"center_x": 0.5}
password: True
MDRoundFlatButton:
text: "LOGIN"
font_size: 12
pos_hint: {"center_x": 0.5}
on_release:
root.manager.current = "homepage"
root.manager.transition.direction = "left"
MDRoundFlatButton:
text: "CLEAR"
font_size: 12
pos_hint: {"center_x": 0.5}
on_press: app.clear()

Widget:
size_hint_y: None
height: 50

<Nav>:
ScrollView:
MDList:
OneLineListItem:
text: "Add New Customer"
on_release:
root.nav_drawer.set_state("close")
root.screen_manager.current = "addNewCustomer"
root.screen_manager.transition.direction = "right"


OneLineListItem:
text: "Add New Staff"
font_size: 15
halign: "center"
on_release:
root.nav_drawer.set_state("close")
root.screen_manager.current = "addNewStaff"
OneLineListItem:
text: "Case List"
font_size: 15
halign: "center"
on_release:
root.nav_drawer.set_state("close")
root.screen_manager.current = "caseList"

OneLineListItem:
text: "Log Out"
font_size: 15
halign: "center"
on_release:
root.nav_drawer.set_state("close")
root.screen_manager.transition.direction = "left"
root.screen_manager.current = "login"




<Homepage>:
name: "homepage"
Screen:
BoxLayout:
orientation: 'vertical'
MDToolbar:
title: 'Navigation'
left_action_items: [['menu', lambda x: nav_drawer.set_state('toggle')]]
right_action_items: [["images/asteria.png", lambda x: None]]

elevation:5
Widget:

MDNavigationDrawer:
id: nav_drawer
Nav:
screen_manager: screen_manager
nav_drawer: nav_drawer

MDNavigationLayout:
ScreenManager:
id: screen_manager
Screen:
name: "Homepage"
MDLabel:
text: "Welcome Home"
halign: "center"

Screen:
name: "addNewCustomer"
MDLabel:
text: "Add New customer"
halign: "center"
Screen:
name: "addNewStaff"
MDLabel:
text: "Add New Staff"
halign: "center"
Screen:
name: "caseList"
MDLabel:
text: "Case List"
halign: "center"
Screen:
name: "casePool"
MDLabel:
text: "Case Pool"
halign: "center"

Answer 1

您有两个screen_manager，您需要引用包含<Login>屏幕的那个。因此，只需更改.kv文件:

<Nav>中的这一行:

OneLineListItem:
text: "Log Out"
font_size: 15
halign: "center"
on_release:
root.nav_drawer.set_state("close")
root.screen_manager.transition.direction = "left"
root.manager.current = "login"

<Hompage>中的这一行:

MDNavigationDrawer:
id: nav_drawer
Nav:
screen_manager: screen_manager
nav_drawer: nav_drawer
manager: root.manager

完整.kv文件:

ScreenManager:
Login:
Homepage:
AddNewCustomer:
Nav:
DrawerList:
<Login>:
name: "login"
MDCard:
size_hint: None, None
size: 700, 800
pos_hint: {"center_x": 0.5, "center_y": 0.5}
elevation: 10
padding: 25
spacing: 25
orientation: 'vertical'
Image:
source: 'images/asteria.png'
size: 100, 200
MDLabel:
id: login
font_size: 40
halign: 'center'
size_hint_y: None
height: self.texture_size[1]
padding_y: 15
MDTextFieldRound:
id: user
hint_text: "username"
icon_right: "account"
size_hint_x: None
width: 200
font_size: 18
pos_hint: {"center_x": 0.5}
MDTextFieldRound:
id: password
hint_text: "password"
icon_right: "eye-off"
size_hint_x: None
width: 200
font_size: 18
pos_hint: {"center_x": 0.5}
password: True
MDRoundFlatButton:
text: "LOGIN"
font_size: 12
pos_hint: {"center_x": 0.5}
on_release:
root.manager.current = "homepage"
root.manager.transition.direction = "left"
MDRoundFlatButton:
text: "CLEAR"
font_size: 12
pos_hint: {"center_x": 0.5}
on_press: app.clear()

Widget:
size_hint_y: None
height: 50

<Nav>:
ScrollView:
MDList:
OneLineListItem:
text: "Add New Customer"
on_release:
root.nav_drawer.set_state("close")
root.screen_manager.current = "addNewCustomer"
root.screen_manager.transition.direction = "right"


OneLineListItem:
text: "Add New Staff"
font_size: 15
halign: "center"
on_release:
root.nav_drawer.set_state("close")
root.screen_manager.current = "addNewStaff"
OneLineListItem:
text: "Case List"
font_size: 15
halign: "center"
on_release:
root.nav_drawer.set_state("close")
root.screen_manager.current = "caseList"

OneLineListItem:
text: "Log Out"
font_size: 15
halign: "center"
on_release:
root.nav_drawer.set_state("close")
root.manager.transition.direction = "left"
root.manager.current = "login"

<Homepage>:
name: "homepage"
Screen:
BoxLayout:
orientation: 'vertical'
MDToolbar:
title: 'Navigation'
left_action_items: [['menu', lambda x: nav_drawer.set_state('toggle')]]
right_action_items: [["images/asteria.png", lambda x: None]]

elevation:5
Widget:

MDNavigationDrawer:
id: nav_drawer
Nav:
screen_manager: screen_manager
nav_drawer: nav_drawer
manager: root.manager

MDNavigationLayout:
ScreenManager:
id: screen_manager
Screen:
name: "Homepage"
MDLabel:
text: "Welcome Home"
halign: "center"
Screen:
name: "addNewCustomer"
MDLabel:
text: "Add New customer"
halign: "center"
Screen:
name: "addNewStaff"
MDLabel:
text: "Add New Staff"
halign: "center"
Screen:
name: "caseList"
MDLabel:
text: "Case List"
halign: "center"
Screen:
name: "casePool"
MDLabel:
text: "Case Pool"
halign: "center"