Tkinter Check if StringVar is not empty

Question

I have a StringVar with Tkinter, I want to check that it is not empty. When I run the following condition, it is accepted while the variable is empty.

    if self.var:
        print(self.var)

The printed variable is PY_VAR1.

    if self.var!= 'PY_VAR1':
        print(self.var)

The printed variable is also PY_VAR1.

How to check that the value of self.var is not equal to PY_VAR1?

When I use get, it doesn't work either

    if self.var.get():
        print(self.var.get())

And when I change the value of self.var, with get (), nothing happens.

self.bouton = ttk.Button(self, text="print var", command=self.printvar)

def printvar(self):
      print(self.var.get())

When I click on the button, the value of self.var is displayed and even when I change the value of self.var (), the new value is displayed. But I want to display the new value of self.var without clicking on the button. I want it to display dynamically.

The code you posted doesn't seem to make any sense. The only place you call select_folder is from a button that isn't created until you call select_folder. Please try to create a complete minimal reproducible example - it's really hard to understand what you're asking when we only have a few lines of code. We definitely don't want your whole program, but we need more than what you've posted. If you're truly just asking how to check if a stringvar is empty, what you're doing will work. — Bryan Oakley
– Bryan Oakley, Commented Jul 13, 2020 at 20:06
Why don't you just call select_folder() after you have chosen a folder inside the callback called by menu action? — acw1668
– acw1668, Commented Jul 14, 2020 at 0:34

Abhishek Sriram · Accepted Answer · 2020-07-19 17:59:44Z

2

Try these:

# no.1
if len(string_variable.get()) == 0:
    do_task()

# no.2
'''We use try-except function so we don't get a ValueError if the specified character 
isn't present in the if-condition'''
try:
    if string_variable.index("Any character in a word that needs to be checked"):
        '''If you want to check "PY_Var1", just type('1') or any other character in 
        the if-condition.'''
        do_task()
except:
    do_task()

# If none work, try storing the StringVar in another variable.
new_string_variable = string_variable.get()
if len(new_variable_string) == 0:
    do_task()

# To check if the string variable(StringVar) isn't equal to "any_string".
if (string_variable.get()) != "any_string":
    do_task()

If you still have any problem, feel free to ask any questions!

edited Jul 19, 2020 at 17:59

answered Jul 18, 2020 at 9:51

Abhishek Sriram

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