用户登录后如何更新KivyMD导航抽屉?

Question

我想更新显示用户照片和电子邮件的ContentNavigationDrawer，但我似乎无法访问id。

在下面的login.py代码中，您可以看到我试图使用一个简单的按钮来更新内容抽屉的代码。我错过了什么?

Main.py

from kivy.core.window import Window
from kivy.lang import Builder
from kivy.uix.boxlayout import BoxLayout
from kivymd.app import MDApp
from test_login import LoginScreen
Window.size = (440, 760)
kv = '''
<ContentNavigationDrawer>:
id: content_nav
orientation: "vertical"
AnchorLayout:
anchor_x: "center"
size_hint_y: None
height: 100
FitImage:
id: user_photo
radius: [50,]
size_hint: None, None
size: 100,100
source: 'data/assets/img/profile_photo_placeholder.jpg'
MDLabel:
id: user_email
text: "--"
halign: "center"
font_style: "Button"
size_hint_y: None
height: self.texture_size[1]
ScrollView:
MDList:
OneLineIconListItem:
text: 'Login'
on_release:
root.nav_drawer.set_state("close")
root.screen_manager.current = "go_to_login"
Screen:
MDToolbar:
id: toolbar
pos_hint: {"top": 1}
left_action_items: [["menu", lambda x: nav_drawer.set_state("open")]]
MDNavigationLayout:
x: toolbar.height
ScreenManager:
id: screen_manager
Screen:
name: "words_nav_item"
LoginScreen:
name: "go_to_login"
MDNavigationDrawer:
id: nav_drawer
ContentNavigationDrawer:
screen_manager: screen_manager
nav_drawer: nav_drawer
'''
class ContentNavigationDrawer(BoxLayout):
pass
class main_test(MDApp):
def build(self):
self.content = ContentNavigationDrawer()
self.kv = Builder.load_string(kv)
return self.kv
main_test().run()

Login.py

from kivy.app import App
from kivy.lang import Builder
from kivymd.uix.screen import MDScreen
kv = '''
<LoginScreen>:
MDGridLayout:
cols: 1
padding: [50,40,50,0]
MDGridLayout:
cols: 1
size_hint: 1, None
height: 240
padding: [0,0,0,20]
AnchorLayout:
anchor_x: 'center'
anchor_x: 'center'
anchor_y: 'center'
MDRectangleFlatButton:
text: "Update User Profile "
on_release:
root.update_user_profile()
'''
class LoginScreen(MDScreen):
def __init__(self, **kwargs):
super().__init__(**kwargs)
self.app = App.get_running_app()
Builder.load_string(kv)
def update_user_profile(self):
user_photo = "data/img/profile.png"
user_email = "[e-mail]"
#NOT WORKING
#self.app.content.ids.user_email.text = user_email
# NOT WORKING
#self.app.kv.ids.user_email.text = user_email
# WORKING
self.app.kv.ids.toolbar.pos_hint= {"top": .5}

Answer 1

在您的App的build()方法中，行:

self.content = ContentNavigationDrawer()

正在创建ContentNavigationDrawer的新实例，但是这个新实例不是出现在GUI中的实例。您需要获得对GUI中ContentNavigationDrawer的实际实例的引用。为此，您可以在kv:

中添加另一个id。

MDNavigationDrawer:
id: nav_drawer
ContentNavigationDrawer:
id: content  # new id to access this instance
screen_manager: screen_manager
nav_drawer: nav_drawer

你可以在你的build()方法中使用这个新的id:

class main_test(MDApp):
def build(self):
# self.content = ContentNavigationDrawer()
self.kv = Builder.load_string(kv)
self.content = self.kv.ids.content
return self.kv

然后，在您的update_user_profile()方法中，行:

self.app.content.ids.user_email.text = user_email

应该工作。这一行:

self.app.kv.ids.user_email.text = user_email

可以修改为使用新的id:

self.app.kv.ids.content.ids.user_email.text = user_email