How to check if a radio button is checked but input box is empty in tkinter?

Question

I got this sort of edgy scenario I would like to accomplish in my tinkter app. The way my tinkter app would work is: a user needs to enter in some text. Then select a radio button option. Once a user selects the radio button option some value would be calculated. Now here is the edge case. Basically if a user were to select a radio option without entering a value I would like to show an error message "you need to enter a value into the input box" below the input box.

a snapshot of what I mean:

Here is what my code looks like:

from tkinter import *

class GetInterfaceValues():
    def __init__(self):
        self.root = Tk()
        self.totalValue = StringVar()


        self.root.geometry('900x500')
        self.RadioText = StringVar()

        self.getPeg = Button(self.root, text='calculate kegs values', command=self.findPeg)


        self.quarterlyTextString = 'Keg'
        self.yearlyTextString = 'parKeg'

        self.textInputBox = Text(self.root, relief=RIDGE, height=1, width=6, borderwidth=2)
        self.frequencyText = Label(self.root, text="Frequency")
        self.normalKegRadioButton = Radiobutton(self.root, text="normal Keg", variable=self.RadioText,
                                                value=self.quarterlyTextString, command=self.selectedRadioButtonOption)
        self.parRadioButton = Radiobutton(self.root, text="Par Kegs", variable=self.RadioText, value=self.yearlyTextString,
                                             command=self.selectedRadioButtonOption)
        self.clearButton = Button(self.root, text="Clear",command=self.clear)

        self.textInputBox.pack()
        self.normalKegRadioButton.pack()
        self.parRadioButton.pack()

        self.getPeg.pack()
        self.clearButton.pack()
        self.root.mainloop()

    def selectedRadioButtonOption(self):
        radioButtonFrequencyOption = self.RadioText.get()

        if(radioButtonFrequencyOption == self.quarterlyTextString):
            self.findPeg()
        if(radioButtonFrequencyOption == self.yearlyTextString):
            print(self.yearlyTextString)


    def getTextInput(self):
        result = self.textInputBox.get("1.0", "end")
        results = result.upper()
        results = results.rstrip()
        results = int(results)

        return results


    def clear(self):
        self.parRadioButton.deselect()
        self.normalKegRadioButton.deselect()
        self.textInputBox.delete("1.0", "end")

    def findPeg(self):
        userInput = self.getTextInput()

        lab = userInput * 15
        print(lab)

app = GetInterfaceValues()
app.mainloop()

You already have a callback, def selectedRadioButtonOption. What is stopping you to add a else condition to display your message? — stovfl
– stovfl, Commented May 1, 2020 at 13:16

TheFluffDragon9 · Accepted Answer · 2020-05-01 12:40:53Z

1

You can test if a entry field contains text by using:

if len(entry.get()) > 0:

You can also invoke a function whenever a radiobutton (or entry) is changed using:

myradiobutton = Radiobutton(root, command = thefunction)

Additionally, you can programmatically deselect a radiobutton with:

myradiobutton.deselect()

if that helps.

Putting this together you could do something like this:

def getinput():
    if len(entry.get()) > 0:
        #do whatever you want to do with the input
    else:
        radiobutton.deselect()
        #display your "enter something" message

entry = Entry(root)
radiobutton = Radiobutton(root, text = "Click when done typing", command = getinput)
entry.pack()
radiobutton.pack()

Let me know if I'm missing the point here. :)

answered May 1, 2020 at 12:40

TheFluffDragon9

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1 Comment

Roosevelt H Over a year ago

Hey mate, thank you for the response. This is exactly what i am looking for

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