Kivy'NoneType'对象没有属性'ids' [英] Kivy 'NoneType' object has no attribute 'ids'

问题描述

我在Kivy应用程序中收到以下错误，但是我不确定为什么以及如何解决它:

I am receiving the following error in my Kivy application but I am not sure why and how to fix it:

File "main.py", line 16, in __init__
self.seq_text_box = self.parent.ids.seq_text_box
AttributeError: 'NoneType' object has no attribute 'ids'

基本上，我要做的就是访问MenuBar类的方法中的文本框.我是新手，所以可能是我误会了一些东西.

Basically, all I'm trying to do is access the text box within the methods of the MenuBar class. I'm new to this so it's likely I'm misunderstanding something.

.py文件

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.textinput import TextInput


class SequenceTextBox(TextInput):

    pass
    #...


class MenuBar(BoxLayout):

    def __init__(self, **kwargs):
        super(MenuBar, self).__init__(**kwargs)
        self.seq_text_box = self.parent.ids.seq_text_box

    def go(self):

        print(self.seq_text_box.text)


class MinuRoot(BoxLayout):
    pass


class MinuApp(App):
    pass


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

.kv文件

MinuRoot:

<MinuRoot>:
    orientation: "vertical"
    MenuBar
    SequenceTextBox
        id: seq_text_box

<MenuBar>:
    height: "40dp"
    size_hint_y: None
    Button:
        text: "Go!"
        on_press: root.go()

<SequenceTextBox>:
    focus: True

感谢您的帮助:)

推荐答案

您可以将seq_text_box存储为

You can store seq_text_box as an ObjectProperty of MenuBar and set it in the kv file:

class MenuBar(BoxLayout):
    seq_text_box = ObjectProperty()
    def go(self):
        print(self.seq_text_box.text)

并在kv文件中:

<MinuRoot>:
    orientation: "vertical"
    MenuBar:
        seq_text_box: seq_text_box
    SequenceTextBox:
        id: seq_text_box

收到错误的原因是因为在构造函数中ids尚未根据kv文件中指定的规则进行填充.

The reason you receive the error is because in the constructor the ids haven't been populated from the rules specified in the kv file.

如果您确实想使用普通属性，则可以安排Clock事件:

If you do want to use a plain attribute, you can schedule a Clock event:

class MenuBar(BoxLayout):
    def __init__(self, **kwargs):
        super(MenuBar, self).__init__(**kwargs)
        Clock.schedule_once(self.init_seq_text_box, 0)

    def init_seq_text_box(self, *args):
        self.seq_text_box = self.parent.ids.seq_text_box

当填充ids时，这将安排对下一帧的呼叫init_eq_text_box.

This will schedule a call to init_eq_text_box for the next frame, when ids will be populated.

这篇关于Kivy'NoneType'对象没有属性'ids'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IT屋！