Getting the error- year = int(year_field.get()) ValueError: invalid literal for int() with base 10: ''

Question

I am gettinetting the below error while running the below code, its seems like because Int function is provide with blank without any string. But how to reslove it

Error: year = int(year_field.get())

ValueError: invalid literal for int() with base 10: ''

import calendar module
import calendar

from tkinter import *

#This function displays calendar for a given year
def showCalender():
    gui = Tk()
    gui.config(background='grey')
    gui.title("Calender for the year")
    gui.geometry("550x600")
    year = int(year_field.get())
    gui_content= calendar.calendar(year)
    calYear = Label(gui, text= gui_content, font= "Consolas 10 bold")
    calYear.grid(row=5, column=1,padx=20)
    gui.mainloop()
    
#Driver code
if __name__=='__main__':
    new= Tk()
    new.config(background="grey")
    new.title("Calendar")
    new.geometry("250x140")
    cal= Label(new, text="Calendar", bg='grey', font=("times", 28, "bold"))
    
    #Label for enter year
    year= Label(new, text="Enter year", bg= 'dark grey')
    
    #text box for year input
    year_field =Entry(new)
    button = Button(new, text='Show Calender', fg='Black', bg='Blue', command=showCalender())    
    #adjusting widgets in position
    cal.grid(row=1, column=1)
    year.grid(row=2, column=1)
    year_field(row=2, column=1)
    year_field.grid(row=3, column=1)
    button.grid(row=4, column=1)
    Exit.grid(row=6, column=1)
    new.mainloop()

Answer 1

You should check if the user has input something into year_field :

def showCalender():
    gui = Tk()
    gui.config(background='grey')
    gui.title("Calender for the year")
    gui.geometry("550x600")
    year_str = year_field.get())
    if year_str: # year_str is not empty, can convert
        year = int(year_str)
    else:
        year = 0 # you can put any number here that you think fit.
    gui_content= calendar.calendar(year)
    calYear = Label(gui, text=gui_content, font="Consolas 10 bold")
    calYear.grid(row=5, column=1, padx=20)
    gui.mainloop()

The whole if / else part can be reduced to one line:

def showCalender():
    gui = Tk()
    gui.config(background='grey')
    gui.title("Calender for the year")
    gui.geometry("550x600")
    year = int(year_field.get() or 0)
    gui_content = calendar.calendar(year)
    calYear = Label(gui, text=gui_content, font="Consolas 10 bold")
    calYear.grid(row=5, column=1, padx=20)
    gui.mainloop()