在尝试运行示例kivy应用程序时，我遇到了上述错误。
这是python代码：
main.py。
from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.screenmanager import Screen, ScreenManager, FadeTransition
class MyScreenManager(ScreenManager):
pass
class MainScreen(Screen):
pass
class MailScreen(Screen):
pass
class ProjectScreen(Screen):
pass
class IntroScreen(Screen):
pass
class GsaMain(BoxLayout):
pass
class GsamApp(App):
def build(self):
return MyScreenManager()
GsamApp().run()
名为gsam.kv的kivy文件
MyScreenManager:
IntroScreen:
MainScreen:
PrjcScreen:
MailScreen:
ChatScreen:
<IntroScreen>:
name: 'introscreen'
BoxLayout:
Label:
text: 'Welcome to GSAM'
font_size: 35
BoxLayout:
Label:
text: "Login"
TextInput:
id: login
text: "Login"
Button:
text: "Connect"
on_release: root.current = 'mainpage'
BoxLayout:
Button:
text: 'Project Page'
font_size: 25
on_release: app.root.current = 'main'
<MainScreen>:
name: 'main'
BoxLayout:
Label:
text: 'Your GSAM Portal'
font_size: 35
BoxLayout:
Button:
text: 'Check Mails'
font_size: 25
on_release: app.root.current = 'mailscreen'
canvas:
color: rgba: 1,0,0,1
Rectangle:
size: 50, 50
Label: "Post Projects"
id: projct
Rectangle:
size: 50, 50
Label: "Messages"
id: msgs
<MailScreen>:
name: 'mailscreen'
BoxLayout:
Label:
text: 'GSAM Mail'
font_size: 35
BoxLayout:
Button:
text: 'Chat'
font_size: 25
on_release: app.root.current = 'chat'
<ChatScreen>:
name: 'chatscreen'
BoxLayout:
Label:
text: 'Chat with your Colleagues'
font_size: 35
BoxLayout:
Button:
text: 'Home'
font_size: 25
on_release: app.root.current = 'main'
<PrjcScreen>:
name: 'prjcscreen'
BoxLayout:
Label:
text: 'Community Projects'
font_size: 35
BoxLayout:
Button:
text: 'community Projects'
font_size: 25
on_release: app.root.current = 'main'
GridLayout:
cols: 2
rows: 4
padding: 5
spacing: 5
Label:
text: "Project Title"
TextInput:
id: ptitle
Label:
text: "Project Description"
TextInput:
id: pdescr
我无法弄清楚指向的追溯是什么。
Traceback (most recent call last):
File "main.py", line 28, in <module>
GsamApp().run()
File "/home/afidegnum/gsam/local/lib/python2.7/site-packages/kivy/app.py", line 797, in run
self.load_kv(filename=self.kv_file)
File "/home/afidegnum/gsam/local/lib/python2.7/site-packages/kivy/app.py", line 594, in load_kv
root = Builder.load_file(rfilename)
File "/home/afidegnum/gsam/local/lib/python2.7/site-packages/kivy/lang.py", line 1749, in load_file
return self.load_string(data, **kwargs)
File "/home/afidegnum/gsam/local/lib/python2.7/site-packages/kivy/lang.py", line 1796, in load_string
parser = Parser(content=string, filename=fn)
File "/home/afidegnum/gsam/local/lib/python2.7/site-packages/kivy/lang.py", line 1185, in __init__
self.parse(content)
File "/home/afidegnum/gsam/local/lib/python2.7/site-packages/kivy/lang.py", line 1287, in parse
objects, remaining_lines = self.parse_level(0, lines)
File "/home/afidegnum/gsam/local/lib/python2.7/site-packages/kivy/lang.py", line 1384, in parse_level
level + 1, lines[i:], spaces)
File "/home/afidegnum/gsam/local/lib/python2.7/site-packages/kivy/lang.py", line 1384, in parse_level
level + 1, lines[i:], spaces)
File "/home/afidegnum/gsam/local/lib/python2.7/site-packages/kivy/lang.py", line 1437, in parse_level
if current_property[:3] == 'on_':
TypeError: 'NoneType' object has no attribute '__getitem__'
我需要在python代码中定义函数on_release吗？
答案 0 :(得分：2)
没有ChatScreen。定义一个：
class ChatScreen(Screen):
pass
ProjectScreen应重命名为PrjcScreen以匹配gsam.kv中的名称。 （或更改PrjcScreen中的gsam.kv）
答案 1 :(得分：1)
我已经处理了您的代码，并生成了一个有效的代码。除了上面给出的建议外，我还注意到您的.kv文件中存在许多缩进问题。我在必要时发表了评论，做出了这些更改。在下面找到工作代码：
main.py
from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.screenmanager import Screen, ScreenManager, FadeTransition
class MyScreenManager(ScreenManager):
pass
class MainScreen(Screen):
pass
class MailScreen(Screen):
pass
class ChatScreen(Screen):
pass
class ProjectScreen(Screen):
pass
class IntroScreen(Screen):
pass
class GsaMain(BoxLayout):
pass
class GsamApp(App):
def build(self):
sm = MyScreenManager()
sm.add_widget(IntroScreen(name="introscreen"))
sm.add_widget(MainScreen(name="main"))
sm.add_widget(MailScreen(name="mailscreen"))
sm.add_widget(ProjectScreen(name="prjcscreen"))
sm.add_widget(ChatScreen(name='chat'))
return sm
GsamApp().run()
gsma.kv
<IntroScreen>:
name: 'introscreen'
BoxLayout:
orientation: 'vertical'
padding: 100,100
spacing: 50
Label:
text: 'Welcome to GSAM'
font_size: 35
Label:
text: "Login"
TextInput:
id: login
text: "Login"
# BoxLayout: # this makes the button widget covers the whole page. remove it
Button:
text: "Connect"
on_release: app.root.current = 'main'
Button:
text: 'Project Page'
font_size: 15
on_release: app.root.current = 'prjcscreen'
<MainScreen>:
name: 'main'
BoxLayout:
orientation:'vertical'
padding:100,100
spacing:50
Label:
text: 'Your GSAM Portal'
font_size: 35
# BoxLayout: # remove this. Dont repeat BoxLayout for every widget u want show on the screen except for a good reason. Or better still, ident the BoxLayout as a child of the First Boxlayout
Button:
text: 'Check Mails' # text, font_size,on_realease must not be in the same line with button
font_size: 25
on_release: app.root.current = 'mailscreen'
canvas.before:
Color: # I have reidented Color
rgba: 1,0,0,1 # this line must be here
Rectangle: # Rectangle must ident with Color
size: 50, 50
# Label: "Post Projects" # remove the label here
id: projct # and place it either before of after canvas class
Rectangle:
size: 50, 50
# Label: "Messages"
id: msgs
<MailScreen>:
name: 'mailscreen'
BoxLayout:
Label:
text: 'GSAM Mail'
font_size: 35
Button:
text: 'Chat'
font_size: 25
on_release: app.root.current = 'chat'
<ChatScreen>:
name: 'chatscreen'
BoxLayout:
Label:
text: 'Chat with \nyour Colleagues'
font_size: 35
Button:
text: 'Home'
font_size: 25
on_release: app.root.current = 'main'
<ProjectScreen>:
name: 'prjcscreen'
BoxLayout:
Label:
text: 'Community Projects'
font_size: 35
Button:
text: 'community Projects'
font_size: 25
on_release: app.root.current = 'main'
GridLayout:
cols: 2
rows: 4
padding: 5
spacing: 5
Label:
text: "Project Title"
TextInput:
id: ptitle
Label:
text: "Project Description"
TextInput:
id: pdescr