那些遇到过的问题

有没有办法用 kivy 在屏幕加载时调用函数？

Dav*_*ell 3 python python-3.x kivy

我有一个 kivy 程序，我需要标签来填充屏幕类中函数给出的数据。它可以正确地与更新按钮配合使用，但我也希望它能够在加载时填充标签。这是 python 文件和 kv 文件：

py：

from kivy import *
from kivy.app import App
from kivy.clock import Clock
from kivy.lang import Builder
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.properties import StringProperty
import requests
from bs4 import BeautifulSoup



class CurrentHighScores(Screen):
    highscore = None
    highscore_two = None
    highscore_three = None
    highscore_four = None
    highscore_five = None
    label_start_one = StringProperty(' ')
    label_start_two = StringProperty(' ')
    label_start_three = StringProperty(' ')
    label_start_four = StringProperty(' ')
    label_start_five = StringProperty(' ')

    def speed_scraper(self):

        URL = 'http://algoodspeeders.org/alpr/speederid.php'

        headers = {
            "User-Agent": "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/78.0.3904.108 Safari/537.36"}

        page = requests.get(URL, headers=headers)

        soup = BeautifulSoup(page.content, 'html.parser')

        indexes = [3, 5]
        speed_data = []

        for tbody in soup.findAll('tbody'):
            for tr in tbody.findAll('tr'):
                speed_values = [td.text for td in tr.findAll('td')]
                speed_vals = [speed_values[x] for x in indexes]
                speed_data.append(speed_vals)

        speed_data.sort(reverse=True)
        # print(speed_data[0:5])

        self.highscore = speed_data[0]
        self.highscore_two = speed_data[1]
        self.highscore_three = speed_data[2]
        self.highscore_four = speed_data[3]
        self.highscore_five = speed_data[4]

        self.ids.high_one.text = '1st: ' + str(self.highscore[0]) + ' MPH | ' + 'License Plate No. ' + str(
            self.highscore[1])
        self.ids.high_two.text = '2nd: ' + str(self.highscore_two[0]) + ' MPH | ' + 'License Plate No. ' + str(
            self.highscore_two[1])
        self.ids.high_three.text = '3rd: ' + str(self.highscore_three[0]) + ' MPH | ' + 'License Plate No. ' + str(
            self.highscore_three[1])
        self.ids.high_four.text = '4th: ' + str(self.highscore_four[0]) + ' MPH | ' + 'License Plate No. ' + str(
            self.highscore_four[1])
        self.ids.high_five.text = '5th: ' + str(self.highscore_five[0]) + ' MPH | ' + 'License Plate No. ' + str(
            self.highscore_five[1])

        print('High Scores List')
        print('----------------')
        print('1st: ' + str(self.highscore[0]) + ' MPH | ' + 'License Plate No. ' + str(self.highscore[1]))
        print('2nd: ' + str(self.highscore_two[0]) + ' MPH | ' + 'License Plate No. ' + str(self.highscore_two[1]))
        print('3rd: ' + str(self.highscore_three[0]) + ' MPH | ' + 'License Plate No. ' + str(self.highscore_three[1]))
        print('4th: ' + str(self.highscore_four[0]) + ' MPH | ' + 'License Plate No. ' + str(self.highscore_four[1]))
        print('5th: ' + str(self.highscore_five[0]) + ' MPH | ' + 'License Plate No. ' + str(self.highscore_five[1]))


class ScreenManage(ScreenManager):
    pass


kv = Builder.load_file('algoodspeed.kv')


class AlgoodSpeedApp(App):
    def build(self):
        return kv


if __name__ == '__main__':
    AlgoodSpeedApp().run()
Run Code Online (Sandbox Code Playgroud)

.kv：

ScreenManage:
    CurrentHighScores:

<CurrentHighScores>
    name: 'CurrentHighScores'
    GridLayout:
        cols: 1
        Label:
            name: 'current_high_scores'
            text: 'Current High Speeds For Cooper Rd:'
            font_size: 30

        Label:
            id: high_one
            text: root.label_start_one
        Label:
            id: high_two
            text: root.label_start_two
        Label:
            id: high_three
            text: root.label_start_three
        Label:
            id: high_four
            text: root.label_start_four
        Label:
            id: high_five
            text: root.label_start_five

        Button:
            id: update
            text: 'Update Current High Speeds'
            on_release:
                root.speed_scraper()
Run Code Online (Sandbox Code Playgroud)

我尝试过使用时钟之类的东西来延迟类外的函数调用，但这根本没有帮助。谢谢您的帮助！

Dav*_*ell 7

感谢对我的问题的评论，我做了一些更多的研究并稍微修改了代码，这是我为其他遇到此问题的人提供的发现。我使用 on_pre_enter 来调用我的函数，并在函数内简单地更新“标签”变量，我必须更改 kv 文件中的文本。它看起来是这样的。我留下了一些旧代码，但将其注释掉，这样您就可以看到它之前的样子：

.py:

from kivy import *
from kivy.app import App
from kivy.clock import Clock
from kivy.lang import Builder
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.properties import StringProperty
import requests
from bs4 import BeautifulSoup


class CurrentHighScores(Screen):
    def on_pre_enter(self, *args):
        self.speed_scraper()

    highscore = None
    highscore_two = None
    highscore_three = None
    highscore_four = None
    highscore_five = None


    label_start_one = StringProperty(' ')
    label_start_two = StringProperty(' ')
    label_start_three = StringProperty(' ')
    label_start_four = StringProperty(' ')
    label_start_five = StringProperty(' ')

    def speed_scraper(self):


        URL = 'http://algoodspeeders.org/alpr/speederid.php'

        headers = {
            "User-Agent": "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/78.0.3904.108 Safari/537.36"}

        page = requests.get(URL, headers=headers)

        soup = BeautifulSoup(page.content, 'html.parser')

        indexes = [3, 5]
        speed_data = []

        for tbody in soup.findAll('tbody'):
            for tr in tbody.findAll('tr'):
                speed_values = [td.text for td in tr.findAll('td')]
                speed_vals = [speed_values[x] for x in indexes]
                speed_data.append(speed_vals)

        speed_data.sort(reverse=True)
        # print(speed_data[0:5])

        self.highscore = speed_data[0]
        self.highscore_two = speed_data[1]
        self.highscore_three = speed_data[2]
        self.highscore_four = speed_data[3]
        self.highscore_five = speed_data[4]

        self.label_start_one = ('1st: ' + str(self.highscore[0]) + ' MPH | ' + 'License Plate No. ' + str(
            self.highscore[1]))
        self.label_start_two = ('2nd: ' + str(self.highscore_two[0]) + ' MPH | ' + 'License Plate No. ' + str(
            self.highscore_two[1]))
        self.label_start_three = ('3rd: ' + str(self.highscore_three[0]) + ' MPH | ' + 'License Plate No. ' + str(
            self.highscore_three[1]))
        self.label_start_four = ('4th: ' + str(self.highscore_four[0]) + ' MPH | ' + 'License Plate No. ' + str(
            self.highscore_four[1]))
        self.label_start_five = ('5th: ' + str(self.highscore_five[0]) + ' MPH | ' + 'License Plate No. ' + str(
            self.highscore_five[1]))

        '''self.ids.high_one.text = '1st: ' + str(self.highscore[0]) + ' MPH | ' + 'License Plate No. ' + str(
            self.highscore[1])
        self.ids.high_two.text = '2nd: ' + str(self.highscore_two[0]) + ' MPH | ' + 'License Plate No. ' + str(
            self.highscore_two[1])
        self.ids.high_three.text = '3rd: ' + str(self.highscore_three[0]) + ' MPH | ' + 'License Plate No. ' + str(
            self.highscore_three[1])
        self.ids.high_four.text = '4th: ' + str(self.highscore_four[0]) + ' MPH | ' + 'License Plate No. ' + str(
            self.highscore_four[1])
        self.ids.high_five.text = '5th: ' + str(self.highscore_five[0]) + ' MPH | ' + 'License Plate No. ' + str(
            self.highscore_five[1])

        print('High Scores List')
        print('----------------')
        print('1st: ' + str(self.highscore[0]) + ' MPH | ' + 'License Plate No. ' + str(self.highscore[1]))
        print('2nd: ' + str(self.highscore_two[0]) + ' MPH | ' + 'License Plate No. ' + str(self.highscore_two[1]))
        print('3rd: ' + str(self.highscore_three[0]) + ' MPH | ' + 'License Plate No. ' + str(self.highscore_three[1]))
        print('4th: ' + str(self.highscore_four[0]) + ' MPH | ' + 'License Plate No. ' + str(self.highscore_four[1]))
        print('5th: ' + str(self.highscore_five[0]) + ' MPH | ' + 'License Plate No. ' + str(self.highscore_five[1]))
'''

class ScreenManage(ScreenManager):
    pass


kv = Builder.load_file('algoodspeed.kv')


class AlgoodSpeedApp(App):
    def build(self):
        return kv


if __name__ == '__main__':
    AlgoodSpeedApp().run()
Run Code Online (Sandbox Code Playgroud)

.kv

ScreenManage:
    CurrentHighScores:

<CurrentHighScores>
    name: 'CurrentHighScores'
    on_enter: print('working')
    GridLayout:
        cols: 1
        Label:
            name: 'current_high_scores'
            text: 'Current High Speeds For Cooper Rd:'
            font_size: 30

        Label:
            id: high_one
            text: root.label_start_one
        Label:
            id: high_two
            text: root.label_start_two
        Label:
            id: high_three
            text: root.label_start_three
        Label:
            id: high_four
            text: root.label_start_four
        Label:
            id: high_five
            text: root.label_start_five

        Button:
            id: update
            text: 'Update Current High Speeds'
            on_release:
                root.speed_scraper()
Run Code Online (Sandbox Code Playgroud)

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