ObjectProperty没有属性(Kivy, Python 3.x)

Question

这个问题经常被问到和回答，但我仍然无法让它工作。我想访问一个作为另一个小部件的子部件的小部件。为此，我使用了一个 ObjectProperty。当我尝试访问 ObjectProperty（通过 FileChooser 弹出窗口打开任何文件）以更改标签的文本时，出现此错误：

self.pdfpages.text = "change to this" AttributeError: 'kivy.properties.ObjectProperty' object has no attribute 'text'

我需要初始化 ObjectProperty 吗？还是我的.kv结构有问题？

main.py

import kivy
kivy.require('1.10.0') # replace with your current kivy version !
# Kivy Imports
from kivy.app import App
#UI Eleemnts
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.button import Button
from kivy.uix.popup import Popup
from kivy.uix.scrollview import ScrollView
from kivy.uix.scatter import Scatter
from kivy.uix.image import Image

#Core Elements
from kivy.core.image import Image as CoreImage
from kivy.properties import ObjectProperty

# Python Imports
import os

class Window(BoxLayout):
    #add child widgets (in kv file)
    pass


class PDFView(ScrollView):
    pdfpages = ObjectProperty()

    def newPage(self, filepath):
         #here the error occurs   
         self.pdfpages.text = "change to this"

class SideBar(BoxLayout):
    def openfile(self):
        print("Button pressed")
        OpenDialog().open()

class OpenDialog(Popup):
    def cancelfile(self):
        #close popup
        self.dismiss()
        print("No file opened")

    def openfile(self, path, selection):
        #selection can contain multiple files, [0] is first or only
        self.dismiss()
        print("Opened File: " + os.path.join(path, selection[0]))
        #open PDFView class
        PDFView.newPage(PDFView, os.path.join(path, selection[0]))        


class PDFEditor(App):
    title = "PDFEditor"
    #gets called on startup
    #load program
    def build(self):
        #return root node
        return Window()

if __name__ == '__main__':
    PDFEditor().run()

PDFEditor.kv

<Window>:
    #this is the main (root) "window"
    orientation: "horizontal"
    SideBar:
        size_hint: (.1, 1)
    PDFView:
        size_hint: (.9, 1)

<PDFView>:
    #handler for ObjectProperty
    pdfpages: pdfpages
    Scatter:
    #only zoom
        BoxLayout:
            #add Images in here somehow
            orientation: "vertical"
            Label:
                id: pdfpages
                text: "hi"


<SideBar>:
    orientation: "vertical"
    Button:
        id: btn_openfile
        on_release: root.openfile()
        text: "Open File"
    Label:
        text: "Hello!"

<OpenDialog>:
    title: "Choose File"
    BoxLayout:
        #Fullscreen
        size: root.size
        pos: root.pos
        orientation: "vertical"
        FileChooserListView:
            id: chsr_open
        BoxLayout:
            size_hint_y: None
            height: 30
            Button:
                text: "Cancel"
                on_release: root.cancelfile()
            Button:
                text: "Open"
                on_release: root.openfile(chsr_open.path, chsr_open.selection)

Answer 1

将您的 openfile 方法更改为：

def openfile(self, path, selection):
    #selection can contain multiple files, [0] is first or only
    self.dismiss()
    print("Opened File: " + os.path.join(path, selection[0]))
    #open PDFView class
    PDFView().newPage(PDFView, os.path.join(path, selection[0]))

PDFView是class，PDFView()是这个class的实例，你需要什么

编辑

标签不会改变，因为您正在创建一个新标签而不替换它。因此，如果我理解得很好，您想要的只是替换 PDFView 的文本。有很多方法可以做到这一点，但我不想编辑太多你的代码：试试这个：

...
class OpenDialog(Popup):
    ...
    def openfile(self, path, selection):
        #selection can contain multiple files, [0] is first or only
        self.dismiss()
        print("Opened File: " + os.path.join(path, selection[0]))
        #open PDFView class
        app.window.ids.pdfview.newPage(PDFView, os.path.join(path, selection[0]))
    ...
...

class PDFEditor(App):
    ...
    def build(self):
        #return root node
        self.window = Window()
        return self.window

app = PDFEditor()

if __name__ == '__main__':
    app.run()

在你的 kv 中：

...
<Window>:
    #this is the main (root) "window"
    orientation: "horizontal"
    SideBar:
        size_hint: (.1, 1)
    PDFView:
        id: pdfview
        size_hint: (.9, 1)
...

Answer 2

这里的问题是你设置了一个新实例的文本，它甚至不在 window 上，而不是你已经拥有的那个。
要解决此问题，您需要访问您拥有的那个。

首先，将您的 Window 设为 App 属性，以便稍后引用。

class PDFEditor(App):
    title = "PDFEditor"
    def build(self):
        self.root = Window()
        return self.root

然后在kv

中给PDFView一个id

<Window>:
    orientation: "horizontal"
    SideBar:
        size_hint: (.1, 1)
    PDFView:
        id: pdfview
        size_hint: (.9, 1)

然后在你的 openfile 方法中，你可以得到你之前创建的运行 apps root 属性，就像这样。

def openfile(self, path, selection):
    self.dismiss()
    print("Opened File: " + os.path.join(path, selection[0]))
    app = App.get_running_app()
    pdf = app.root.ids.pdfview
    pdf.newPage(os.path.join(path, selection[0]))

这样您就可以访问 Window class

的 ids

ObjectProperty没有属性(Kivy, Python 3.x)

ObjectProperty has no attribute (Kivy, Python 3.x)

python-3.x

kivy

kivy-language