Question

我遇到了一个关于kivy脚本的AssertionError。代码如下：

import time
from copy import deepcopy as dc
# import modules related to kivy UI
from kivy.app import App
# kivy.require("1.9.1")
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.lang import Builder
from kivy.uix.gridlayout import GridLayout
from kivy.uix.label import Label
from kivy.uix.button import Button
from kivy.uix.image import Image
# define global variables just for testing
temperature = str(25)+"°C"
humidity = str(95)+'%'
last_water = "15/04/2018 15:40"
time_next = str(4)+' hr'

kv = """
<LeftScreen>:
    GridLayout:
        cols: 2     
        Image:
            id: im
            source: 'C:/Users/Acer/Documents/Python Scripts/sakura.jpg'
            size_hint: 0.5, 0.5
        Label:
            id: title
            text: '[b][i]Smart[/i]'+' Gardener[/b]'
            color: (0.25,0.5,0.1,1)
            font_size: 60
            font_name: 'times'
        Label:
            id: group
            text: '[i]group 8[/i]'
            color: (0.3,0.3,0.6,1)
            font_size: 45
            font_name: 'Arial'
            valign: 'bottom'
        Label: 
            id: lastU
            text: '[i]'+'Last Update: '+time.striftime("%H:%M:%S")+'[/i]'
            font_size: 18
            halign: 'center'
            valign: 'middle'
        Button:
            id: update
            text: 'Refresh'
            font_size: 20
            halign: 'center'
            valign: 'middle'
            on_press: root.reload()
        Label:
            id: temp_lbl
            text: 'Temperature: '
            font_size: 24
            halign: 'center'
            valign: 'middle'
        Label:
            id: temp_val
            text: root.temp
            font_size: 24
            halign: 'center'
            valign: 'middle'
        Label:
            id: hum_lbl
            text: 'Humidity: '
            font_size: 24
            halign: 'center'
            valign: 'middle'
        Label:
            id: hum_val
            text: root.hum
            font_size: 24
            halign: 'center'
            valign: 'middle'
        Label:
            id: lastW_lbl
            text: 'Last Watering: '
            font_size: 24
            halign: 'center'
            valign: 'middle'
        Label:
            id: lastW_val
            text: root.last_water
            font_size: 24
            halign: 'center'
            valign: 'middle'
        Label:
            id: nextW_lbl
            text: 'Time before Next Watering: '
            font_size: 24
            halign: 'center'
            valign: 'middle'
        Label:
            id: nextW_val
            text: root.time_text
            font_size: 24
            halign: 'center'
            valign: 'middle'
    """
Builder.load_string(kv)
# create the left screen
class LeftScreen(Screen):
    def __init__(self, **kwargs):
        super(LeftScreen, self).__init__(**kwargs)
        self.temp = dc(temperature)
        self.hum = dc(humidity)
        self.last_water = dc(last_water)
        self.time_next = dc(time_next)

    def reload(self,value):
        self.ids.lastU.text='Last Update: '+time.strftime("%H:%M:%S")
        self.ids.temp_val.text=temperature
        self.ids.hum_val.text=humidity
        self.ids.lastW_val.text=last_water
        self.ids.nextW_val.text=time_next

class RightScreen(Screen):
    def __init__(self,**kwargs):
        super(RightScreen,self).__init__(**kwargs)
        self.layout = GridLayout()
        self.add_widget(self.layout)

class SmartGardener(App):
    def build(self):
        sm = ScreenManager()
        ls = LeftScreen(name='data')
        sm.add_widget(ls)
        sm.current = 'data'
        return sm        

def reset():
    import kivy.core.window as window
    from kivy.base import EventLoop
    if not EventLoop.event_listeners:
        from kivy.cache import Cache
        window.Window = window.core_select_lib('window', \
        window.window_impl, True)
        Cache.print_usage()
        for cat in Cache._categories:
            Cache._objects[cat] = {}
myApp = SmartGardener()
if __name__ == '__main__':
    reset()
    myApp.run()

我插入的图像或我用于标签的变量是否有错误？我想插入图像作为UI的背景。

此外，变量＆＃39; time_next＆＃39;似乎有些错误。当我试图从kivy文件访问它时。访问属性的正确方法是什么？time_next＆＃39; kv引用中的对象MainScreen？

Answer 1

好的，我试图运行你的代码，这就是我发现的：

您尝试访问＆＃39; time_text＆＃39;在kv文件中，当你在课程中设置时间＆＃39;，这是一个错字，但即使在我修复它之后我还必须在你调用的所有变量的kv文件中设置默认值，哼， temp，time_next，last_water：
```
<LeftScreen>:
    time_text: ''
    last_water:''
    hum: ''
    temp: ''
    GridLayout:
        cols: 2 
        ...
```
接下来你使用time.striftime这是一个错误的time.strftime，但你需要在kv代码中导入它，如下所示：
```
:import strftime time.strftime
<LeftScreen>:
...
```
并使用它：
```
Label: 
    id: lastU
    text: '[i]'+'Last Update: '+strftime("%H:%M:%S")+'[/i]'
```
请参阅kv语言文档：special syntax

我还没有能够运行你的代码，我没有你使用的字体，所以我只是评论了这些线条，一旦它运行我发现标签＆＃39; s显示标记，要使用它，您需要明确设置markupe=True

Label:
    id: title
    text: '[b][i]Smart[/i]'+' Gardener[/b]'
    markup: True
    color: (0.25,0.5,0.1,1)
    font_size: 60
    #font_name: 'times'
Label:
    id: group
    text: '[i]group 8[/i]'
    markup: True
    color: (0.3,0.3,0.6,1)
    font_size: 45
    #font_name: 'Arial'
    valign: 'bottom'

最后，单击刷新按钮会调用reload而没有任何值，而它需要一些值，因此刷新＆＃39;按钮会引发TypeError。

Python / Kivy中的AssertionError

1 个答案: