PySimpleGUI：如何使用以下方法将值从字符串转换为浮点数

Question

我有一个简短的 PySimpleGUI 程序来测试 FocusOut。 Jason Yang 提供的代码完全符合我的要求。但是，出现了一个新问题，因此我将其作为一个新问题发布。在下面的代码中，如果输入失败并在“FUELQUANT”字段中输入金额，则会引发错误并生成弹出窗口。但是，如果您输入一个值，例如 13.5，我希望它在收件箱中反映为 13.50。为此，我想读取字段中的值，然后将其格式化为小数点后 2 位，并通过 .update 将其 return 发送到收件箱。我的问题是，一旦我输入格式代码行，如果收件箱中没有值（即当它应该导致弹出窗口激活时），我就会收到错误消息：“无法将字符串转换为浮动：''“有办法解决这个问题吗？我已经尝试了我能找到的所有方法来尝试解决问题，但似乎没有任何效果。

import PySimpleGUI as sg
from tkcalendar import Calendar, DateEntry
import sqlite3
from datetime import date
import time

TodayDt=date.today()
print("Today's date is " + str(TodayDt))


def popup(*args, elem=None):
    for element in elements:
        element.unbind('<FocusOut>')
    window.refresh()                        # Make unbind effect
    layout = [
        [sg.Text('\n'.join(args))],
        [sg.Button('OK')],
    ]
    sg.Window('Popup', layout).read(close=True)
    if elem:
        elem.set_focus()
        window.refresh()                    # Make set_focus effect
    for element in elements:
        element.bind('<FocusOut>','+FOCUS OUT')

layout=[
[sg.T("Today's date is:"),sg.InputText(TodayDt, size=(10, 10), key='_TODAYCAL_')],
[sg.T("Select new transaction date:"),sg.CalendarButton('Calendar',  target='-IN4-', key='_DATE_',format='%Y-%m-%d'),sg.In(key='-IN4-', size=(10,1))],
[sg.T("Fuel quantity (in litres):"),sg.In(key="_FUELQUANT_",size=(10,1),enable_events=True),sg.T("Fuel amount N$:"),sg.In(key="_FUELAMNT_", size=(10,1),enable_events=True)],
[sg.T("Oil quantity (in millilitres:"),sg.In(key="_OILQUANT_",size=(10,1)),sg.T("Oil amount N$:"),sg.In(key="_OILAMNT_",size=(10,1))],
]
window = sg.Window('My Vehicle Logbook', layout, finalize=True)
keys = ('_FUELQUANT_','_FUELAMNT_')
elements = [window[key] for key in keys]
for element in elements:
    element.bind('<FocusOut>','+FOCUS OUT')

while True:
    event, values = window.read()

    if event == sg.WIN_CLOSED or event == 'Cancel':     # if user closes window or clicks cancel
        break

    elif event.endswith("+FOCUS OUT"):

        print(event)
        key = event.split('+')[0]

        amount=values[key]
        print(str(amount))
        
        #amount="{: .2f}".format(float(amount))
        # window.find_element(key).update(amount)
        print(amount)
        if values[key] == '':
            popup("Warning", f"Blank entry in {key} is not acceptable !", elem=window[key])

window.close()

Answer 1

是关于编程逻辑的。

它的演示代码

import PySimpleGUI as sg

def popup(*args, elem=None):
    for element in elements:
        element.unbind('<FocusOut>')
    window.refresh()                        # Make unbind effect
    layout = [
        [sg.Text('\n'.join(args))],
        [sg.Button('OK')],
    ]
    sg.Window('Popup', layout).read(close=True)
    if elem:
        elem.set_focus()
        window.refresh()                    # Make set_focus effect
    for element in elements:
        element.bind('<FocusOut>','+FOCUS OUT')

layout=[[sg.Input(key=f'-IN{i}-')] for i in range(5)]

window = sg.Window('My Vehicle Logbook', layout, finalize=True)
keys = ('-IN1-', '-IN2-')
elements = [window[key] for key in keys]
for element in elements:
    element.bind('<FocusOut>','+FOCUS OUT')

while True:
    event, values = window.read()

    if event == sg.WIN_CLOSED or event == 'Cancel':     # if user closes window or clicks cancel
        break
    elif event.endswith("+FOCUS OUT"):
        key = event.split('+')[0]
        try:
            number = float(values[key])
            string = f'{number:.2f}'
            window[key].update(string)
        except ValueError:
            popup("Warning", "Wrong format for a float number !", elem=window[key])

window.close()

如果切换到其他程序仍然会出现问题，当焦点位于任何绑定输入时，它仍然会生成 FocusOut 事件。在单击一个按钮 submit 后验证所有输入可能更好。

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