Validating Input Value - PySimpleGUI

Question

I have simple GUI with two inputs and exit button. Inputs have default_value = 0.00. I want to validate user change in the way that input can be only float format,'.2f' and <= 5.0. Example from cookbook helps partially. When I use this code:

import PySimpleGUI as sg

layout = [[sg.Input(key='first_input', enable_events=True, default_text='0.00')],
          [sg.Input(key='second_input', enable_events=True, default_text='0.00')],
          [sg.Button('Exit')]]

window = sg.Window('Main', layout)

while True:
    event, values = window.read()
    if event in ['Exit', sg.WIN_CLOSED]:
        break
    if event == 'first_input' and values['first_input']:
        try:
            in_as_float = float(values['first_input'])
            if float(values['first_input']) > 5:
                window['first_input'].update('5')
        except:
            if len(values['first_input']) == 1 and values['first_input'][0] == '-':
                continue
            window['first_input'].update(values['first_input'][:-1])

window.close()

But when user delete content of "first_input" and decide to fill "second_input" the previous one remains empty. How to prevent it and for example back to default value when user left input empty.

I have tried to do someting like:

if values['first_input'] == '':
   window['firs_input'].update['0.00']

but this do not work because it will not let to user delete content. For example when he want to change from 3 to 4. After he delete 3 0.00 apears immediately.

Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking. — Community, Nov 01 '21 at 13:09

score 2 · Accepted Answer · answered Nov 01 '21 at 15:15

Try to validate value by regex, maybe you can test it meet all requirements.

import re
import PySimpleGUI as sg

def select(element):
    element.Widget.select_range(0, 'end')
    element.Widget.icursor('end')

def validate(text):
    result = re.match(regex, text)
    return False if result is None or result.group() != text else True

regex = "^[+-]?([0-5](\.(\d{0,2}))?)?$"
old = {'IN1':'0.00', 'IN2':'0.00'}
validate_inputs = ('IN1', 'IN2')

layout = [
    [sg.Input('0.00', enable_events=True, key='IN1')],
    [sg.Input('0.00', enable_events=True, key='IN2')],
    [sg.Button('Exit')],
]

window = sg.Window('Title', layout, finalize=True)
select(window['IN1'])
for key in validate_inputs:
    window[key].bind('<FocusIn>',  ' IN')
    window[key].bind('<FocusOut>', ' OUT')

while True:
    event, values = window.read()
    if event in ['Exit', sg.WIN_CLOSED]:
        break
    elif event in validate_inputs:
        element, text = window[event], values[event]
        if validate(text):
            try:
                v = float(text)
                if v > 5:
                    element.update(old[event])
                    continue
            except ValueError as e:
                pass
            old[event] = text
        else:
            element.update(old[event])
    elif event.endswith(' IN'):
        key = event.split()[0]
        element, text = window[key], values[key]
        select(element)
    elif event.endswith(' OUT'):
        key = event.split()[0]
        element, text = window[key], values[key]
        try:
            v = float(text)
            element.update(f'{v:.2f}')
        except ValueError as e:
            element.update('0.00')

window.close()

Thank you! It works now exactly as I wanted. A lot of interesting line in your code I can learn from. Cheers! — marekp3, Nov 02 '21 at 11:28

Validating Input Value - PySimpleGUI

1 Answers1