本文介绍了错误:在_update_shadow self._shadow = App.get_running_app().theme_cls.quad_shadow中的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我正在Kivy和KivyMD中构建用于登录功能的GUI.我的GUI可以与Kivy代码一起正常工作，但是第二次我将Button更改为MDRaisedButton，我得到了这两个错误(下面将提供完整的错误代码):

I'm working in Kivy and KivyMD to build a GUI for a login function. My GUI works fine with Kivy code, but the second I change a Button to an MDRaisedButton, I get these two errors (full error code further below):

AttributeError:"NoneType"对象没有属性"theme_cls"
第118行，在_update_shadow中 self._shadow = App.get_running_app().theme_cls.quad_shadow

AttributeError: 'NoneType' object has no attribute 'theme_cls'
line 118, in _update_shadow self._shadow = App.get_running_app().theme_cls.quad_shadow

我很想知道是否还有其他人可以找出问题所在，并向我解释.谢谢！

I'm curious to know if anyone else can pinpoint the problem, and explain it to me. Thank you!

过去的8个小时中，我将整个应用程序从空白页重建到一个新页，在两次编辑之间运行代码，以查看是否可以确定它的中断位置.不幸的是，我无法解决该问题.

I spent the past 8 hours rebuilding the entire application from a blank page to a new one, running the code between edits to see if I could pinpoint where it was breaking. Unfortunately, I couldn't figure out a solution to the problem.

framedesign.py

class LoginWindow(Screen):
    email = ObjectProperty(None)
    password = ObjectProperty(None)

    def loginBtn(self):
        if db.validate(self.email.text, self.password.text):
            MainWindow.current = self.email.text
            self.reset()
            sm.current = "main"
        else:
            invalidLogin()

    def createBtn(self):
        self.reset()
        sm.current = "create"

    def reset(self):
        self.email.text = ""
        self.password.text = ""

class WindowManager(ScreenManager):
    pass

sm = WindowManager()

screens = [LoginWindow(name="login"), CreateAccountWindow(name="create"), MainWindow(name="main")]
for screen in screens:
    sm.add_widget(screen)

sm.current = "login"

class FrameWork(App):
    theme_cls = ThemeManager()
    theme_cls.primary_palette = "DeepPurple"
    title = "Frame Work"

    def build(self):
        return sm

design.kv:

<WindowManager>:
    LoginWindow:
        name: "login"

        email: email
        password: password
        MDRaisedButton:
           pos_hint:{"x":0.2,"y":0.05}
           size_hint: 0.6, 0.2
           font_size: (root.width**2 + root.height**2) / 13**4
           text: "Login"
           on_release:
              root.manager.transition.direction = "up"
              root.loginBtn()

Traceback (most recent call last):
   File "C:\Users\tsuyu\PycharmProjects\waverunners-ocr\venv\lib\site-packages\kivy\lang\builder.py", line 696, in _apply_rule
     setattr(widget_set, key, value)
   File "kivy\weakproxy.pyx", line 35, in kivy.weakproxy.WeakProxy.__setattr__
   File "kivy\properties.pyx", line 497, in kivy.properties.Property.__set__
   File "kivy\properties.pyx", line 544, in kivy.properties.Property.set
   File "kivy\properties.pyx", line 599, in kivy.properties.Property.dispatch
   File "kivy\_event.pyx", line 1214, in kivy._event.EventObservers.dispatch
   File "kivy\_event.pyx", line 1120, in kivy._event.EventObservers._dispatch
   File "kivy\properties.pyx", line 1318, in kivy.properties.ReferenceListProperty.trigger_change
   File "kivy\properties.pyx", line 1333, in kivy.properties.ReferenceListProperty.trigger_change
   File "kivy\properties.pyx", line 599, in kivy.properties.Property.dispatch
   File "kivy\_event.pyx", line 1214, in kivy._event.EventObservers.dispatch
   File "kivy\_event.pyx", line 1120, in kivy._event.EventObservers._dispatch
   File "C:\Users\tsuyu\PycharmProjects\waverunners-ocr\venv\lib\site-packages\kivymd\elevation.py", line 118, in _update_shadow
     self._shadow = App.get_running_app().theme_cls.quad_shadow
 AttributeError: 'NoneType' object has no attribute 'theme_cls'

 During handling of the above exception, another exception occurred:

 Traceback (most recent call last):
   File "C:/Users/tsuyu/PycharmProjects/waverunners-ocr/venv/Scripts/framedesign.py", line 132, in <module>
     sm = WindowManager()
   File "C:\Users\tsuyu\PycharmProjects\waverunners-ocr\venv\lib\site-packages\kivy\uix\screenmanager.py", line 968, in __init__
     super(ScreenManager, self).__init__(**kwargs)
   File "C:\Users\tsuyu\PycharmProjects\waverunners-ocr\venv\lib\site-packages\kivy\uix\floatlayout.py", line 65, in __init__
     super(FloatLayout, self).__init__(**kwargs)
   File "C:\Users\tsuyu\PycharmProjects\waverunners-ocr\venv\lib\site-packages\kivy\uix\layout.py", line 76, in __init__
     super(Layout, self).__init__(**kwargs)
   File "C:\Users\tsuyu\PycharmProjects\waverunners-ocr\venv\lib\site-packages\kivy\uix\widget.py", line 361, in __init__
     rule_children=rule_children)
   File "C:\Users\tsuyu\PycharmProjects\waverunners-ocr\venv\lib\site-packages\kivy\uix\widget.py", line 469, in apply_class_lang_rules
     rule_children=rule_children)
   File "C:\Users\tsuyu\PycharmProjects\waverunners-ocr\venv\lib\site-packages\kivy\lang\builder.py", line 538, in apply
     rule_children=rule_children)
   File "C:\Users\tsuyu\PycharmProjects\waverunners-ocr\venv\lib\site-packages\kivy\lang\builder.py", line 659, in _apply_rule
     child, crule, rootrule, rule_children=rule_children)
   File "C:\Users\tsuyu\PycharmProjects\waverunners-ocr\venv\lib\site-packages\kivy\lang\builder.py", line 659, in _apply_rule
     child, crule, rootrule, rule_children=rule_children)
   File "C:\Users\tsuyu\PycharmProjects\waverunners-ocr\venv\lib\site-packages\kivy\lang\builder.py", line 657, in _apply_rule
     root=rctx['ids']['root'], rule_children=rule_children)
   File "C:\Users\tsuyu\PycharmProjects\waverunners-ocr\venv\lib\site-packages\kivy\uix\widget.py", line 469, in apply_class_lang_rules
     rule_children=rule_children)
   File "C:\Users\tsuyu\PycharmProjects\waverunners-ocr\venv\lib\site-packages\kivy\lang\builder.py", line 538, in apply
     rule_children=rule_children)
   File "C:\Users\tsuyu\PycharmProjects\waverunners-ocr\venv\lib\site-packages\kivy\lang\builder.py", line 707, in _apply_rule
     e), cause=tb)
 kivy.lang.builder.BuilderException: Parser: File "<inline>", line 58:
 ...
      56:
      57:    lbl_txt: lbl_txt
 >>   58:    height: dp(36) if not root._height else root._height
      59:    width: lbl_txt.texture_size[0] + root.increment_width
      60:    padding: (dp(8), 0)
 ...
 AttributeError: 'NoneType' object has no attribute 'theme_cls'
   File "C:\Users\tsuyu\PycharmProjects\waverunners-ocr\venv\lib\site-packages\kivy\lang\builder.py", line 696, in _apply_rule
     setattr(widget_set, key, value)
   File "kivy\weakproxy.pyx", line 35, in kivy.weakproxy.WeakProxy.__setattr__
   File "kivy\properties.pyx", line 497, in kivy.properties.Property.__set__
   File "kivy\properties.pyx", line 544, in kivy.properties.Property.set
   File "kivy\properties.pyx", line 599, in kivy.properties.Property.dispatch
   File "kivy\_event.pyx", line 1214, in kivy._event.EventObservers.dispatch
   File "kivy\_event.pyx", line 1120, in kivy._event.EventObservers._dispatch
   File "kivy\properties.pyx", line 1318, in kivy.properties.ReferenceListProperty.trigger_change
   File "kivy\properties.pyx", line 1333, in kivy.properties.ReferenceListProperty.trigger_change
   File "kivy\properties.pyx", line 599, in kivy.properties.Property.dispatch
   File "kivy\_event.pyx", line 1214, in kivy._event.EventObservers.dispatch
   File "kivy\_event.pyx", line 1120, in kivy._event.EventObservers._dispatch
   File "C:\Users\tsuyu\PycharmProjects\waverunners-ocr\venv\lib\site-packages\kivymd\elevation.py", line 118, in _update_shadow
     self._shadow = App.get_running_app().theme_cls.quad_shadow

问题的根本原因

问题是因为实例化WindowManager对象sm = WindowManager()时未定义theme_cls.

解决方案是在实例化theme_cls = ThemeManager()之后实例化WindowManager().

The solution is to instantiate the WindowManager() after instantiated theme_cls = ThemeManager().

用return WindowManager()替换return sm
删除以下代码行并实现add_widget()(又名实例化孩子)

Replace return sm with returnWindowManager()`
Remove the following lines of code and implement add_widget() (aka instantiate children) in kv file

sm = WindowManager()

screens = [LoginWindow(name="login"), CreateAccountWindow(name="create"), MainWindow(name="main")]
for screen in screens:
    sm.add_widget(screen)

sm.current = "login"

class WindowManager(ScreenManager):
    pass


class FrameWork(App):
    theme_cls = ThemeManager()
    theme_cls.primary_palette = "DeepPurple"
    title = "Frame Work"

    def build(self):
        return WindowManager()

kv文件

将屏幕(CreateAccountWindow和MainWindow)实例化为类规则<WindowManager>:

kv file

Instantiate the screens (CreateAccountWindow, and MainWindow)as children of class rule, <WindowManager>:

<WindowManager>:
    LoginWindow:
        name: "login"
    CreateAccountWindow:
        name: "create"
    MainWindow:
        name: "main"

示例

以下示例是使用Kivy(ScreenManager，屏幕，标签，弹出窗口，FloatLayout，GridLayout)和KivyMD(例如ThemeManager，MDLabel，MDTextField，MDRaisedButton，MDRectangleFlatButton)制作的应用程序模型.

Example

The following example is a mock-up of your app using Kivy (ScreenManager, Screen, Label, Popup, FloatLayout, GridLayout) and KivyMD (e.g. ThemeManager, MDLabel, MDTextField, MDRaisedButton, MDRectangleFlatButton).

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.uix.label import Label
from kivy.uix.popup import Popup
from kivy.properties import ObjectProperty

from kivymd.theming import ThemeManager

from database import DataBase as db

Builder.load_string("""
#:import MDLabel kivymd.label.MDLabel
#:import MDTextField kivymd.textfields.MDTextField
#:import MDRaisedButton kivymd.button.MDRaisedButton
#:import MDRectangleFlatButton kivymd.button.MDRectangleFlatButton

<WindowManager>:
    LoginWindow:
        name: "login"
    CreateAccountWindow:
        name: "create"
    MainWindow:
        name: "main"

<LoginWindow>:        

    namee: namee
    email: email
    password: passw
    bikebrand: bikebrand

    FloatLayout:

        FloatLayout:
            size: root.width, root.height/2

            MDLabel:
                text: "Create an Account"
                size_hint: 0.8, 0.2
                pos_hint: {"x":0.1, "top":1}
                font_size: (root.width**2 + root.height**2) / 14**4

            MDLabel:
                size_hint: 0.26,0.15
                pos_hint: {"x":0, "top":0.8}
                text: "Name: "
                font_size: (root.width**2 + root.height**2) / 14**4

            MDTextField:
                helper_text: "Name"
                helper_text_mode: "on_focus"
                pos_hint: {"x":0.3, "top":0.76}
                size_hint: 0.5, 0.08
                id: namee
                multiline: False
                font_size: (root.width**2 + root.height**2) / 14**4

            MDLabel:
                size_hint: 0.26,0.15
                pos_hint: {"x":0, "top":0.7}
                text: "Email: "
                font_size: (root.width**2 + root.height**2) / 14**4

            MDTextField:
                helper_text: "e.g. [email protected]"
                helper_text_mode: "on_focus"
                pos_hint: {"x":0.3, "top":0.66}
                size_hint: 0.5, 0.08
                id: email
                multiline: False
                font_size: (root.width**2 + root.height**2) / 14**4

            MDLabel:
                size_hint: 0.2,0.15
                pos_hint: {"x":0, "top":0.6}
                text: "Password: "
                font_size: (root.width**2 + root.height**2) / 14**4

            MDTextField:            
                helper_text: "Must contain Symbols:( e.g. @#$% ), Numbers:( e.g. 123456 ), Lowercase Characters:( e.g. abcdefgh ) and Uppercase Characters:( e.g. ABCDEFGH )"
                helper_text_mode: "on_focus"
                pos_hint: {"x":0.3, "top":0.56}
                size_hint: 0.5, 0.08
                id: passw
                multiline: False
                password: True
                font_size: (root.width**2 + root.height**2) / 14**4

            MDLabel:
                size_hint: 0.26,0.15
                pos_hint: {"x":0, "top":0.5}
                text: "Bike: "
                font_size: (root.width**2 + root.height**2) / 14**4

            Spinner:
                id: bikebrand
                on_text:
                    print("kv: bikebrand.text={}".format(bikebrand.text))
                text: "<Select>"
                values: ['Brand A', 'Brand B', 'Brand C', 'Brand D', 'Brand E', 'Brand F', 'Brand G', 'Brand H', 'Brand I']
                # background_color: 1,1,1,1
                color: 0,0,0,1
                color_down: 0,0,0,1
                size_hint: 0.5, 0.08
                pos_hint: {"x":0.3, "top":0.46}

            MDRectangleFlatButton:
                pos_hint:{"x":0.3,"y":0.25}
                size_hint: 0.5, 0.1
                font_size: (root.width**2 + root.height**2) / 15**4
                text: "Already have an Account? Log In"
                background_color: 0.68, 0.8, 0.5, 0.18
                color: 0,0,0,1
                on_release:
                    root.manager.transition.direction = "left"
                    root.loginBtn()

            MDRaisedButton:
                pos_hint:{"x":0.2,"y":0.05}
                size_hint: 0.6, 0.2
                font_size: (root.width**2 + root.height**2) / 13**4
                text: "Create Account"
                on_release:
                    root.manager.transition.direction = "up"
                    root.createBtn()

<CreateAccountWindow>:
    GridLayout:
        cols: 1

        MDRaisedButton:
            text: 'Goto MainWindow'
            on_release: root.manager.current = 'main'

        MDLabel:
            text: 'Create Account Window'
            font_size: sp(50)

<MainWindow>:
    GridLayout:
        cols: 1

        MDRaisedButton:
            text: 'Goto LoginWindow'
            on_release: root.manager.current = 'login'

        MDLabel:
            text: 'Main Window'
            font_size: sp(50)

""")


def invalidLogin():
    pop = Popup(title='Invalid Login',
                content=Label(text='Invalid username or password.'),
                size_hint=(None, None), size=(400, 400))
    pop.open()


def invalidForm():
    pop = Popup(title='Invalid Form',
                content=Label(text='Please fill in all inputs with valid information.'),
                size_hint=(None, None), size=(400, 400))

    pop.open()


class LoginWindow(Screen):
    email = ObjectProperty(None)
    password = ObjectProperty(None)

    def loginBtn(self):
        self._shadow = App.get_running_app().theme_cls.quad_shadow
        print(f"\nloginBtn: self._shadow={self._shadow}")

        if db.validate(self.email.text, self.password.text):
            MainWindow.current = self.email.text
            self.reset()
            self.manager.current = "main"
        else:
            invalidLogin()

    def createBtn(self):
        self.reset()
        self.manager.current = "create"

    def reset(self):
        self.email.text = ""
        self.password.text = ""


class CreateAccountWindow(Screen):
    pass


class MainWindow(Screen):
    pass


class WindowManager(ScreenManager):
    pass


class FrameWork(App):
    theme_cls = ThemeManager()
    theme_cls.primary_palette = "DeepPurple"
    title = "Frame Work"

    def build(self):
        return WindowManager()


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

输出

这篇关于错误:在_update_shadow self._shadow = App.get_running_app().theme_cls.quad_shadow中的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！

Kivy

错误:在_update_shadow self._shadow = App.get_running_app().theme_cls.quad_shadow中

问题描述

推荐答案

问题的根本原因

kv文件

kv file

示例

Example

输出