Adding and updating new widget in tkinter in runtime

Question

I am trying to build a GUI creator using Python and Tkinter, but ran into a problem.

My problem is How to add\update widgets in runtime?

for example:

• I have created the main window.
• In that main window, I have created a frame name w_frame which contains a bunch of widget.
• Based on my input in the Text or Entry widget beside the w_frame, I want to update a particular widget.
• Lets say w_frame contains a Entry widget, radio button, button and label all available with the basic or main attributes need to display it.
• Now I want to change the background color of label.
• In short I want to write the code label_name.property_name=value or for example a_label.bg=red in the text widget and as soon as I press apply button, the widget should change.

I have searched on web, but not able to find the required solution. Also tried using How can i update a certain widget in tkinter, but that does not work depending on my input.

from tkinter import *
root=Tk()
w_frame=Frame()
w_frame.pack()
def update_Frame():
    a=u_text_wid.get("1.0",END)
    b.config(a)
    root.update()
def add_wid_in_frame():
    global a,b
    a=Button(w_frame,text='heelo')
    a.pack()
    b=Label(w_frame,text='heelo')
    b.pack()
u_text_wid=Text()
u_text_wid.pack()
button1=Button(text="add",command=add_wid_in_frame)
button1.pack()
button1=Button(text="update",command=update_Frame)
button1.pack()
root.mainloop()

this results me in an error

unknown option "-bg="red"

Note: I want to update the widget based on the property value provided by the user, so it wont be hard-code into the script.

Answer 1

You are getting the error because every thing you retrieve from Text widget is a string and you cannot directly pass an string to .config method, you need a keyword and then you can assign value which can be string.

According to your question and the comments on the question, what i have figured out is:

• You want to run lable.config(bg='red') from the Text widget.
• You want to change the property of specific widget.

Here's what you can do:

1. To run Tkinter code form Text widget, you can use:

• getattr method
• eval method

4. Just to change property of widget:

def update_Frame():
    global bcd
    a = u_text_wid.get("1.0", "end-1c")
    b=a.split(",")
    c=[tuple(i.split("=")) if "=" in i else i for i in b]
    d=dict(i for i in c)
    for key,value in d.items():
        bcd[key]=value

• We can use string to change property only in this format widget_name[key]=value.

Some Useful Links:

• Eval()
• Getattr()

Answer 2

For your case, you can use ast.literal_eval() to convert a JSON string to dictionary and use the dictionary in .config():

from ast import literal_eval
...
def update_Frame():
    a = u_text_wid.get("1.0", "end-1c") # don't include ending newline
    cnf = literal_eval(a) # convert JSON string to dictionary
    b.config(cnf)

Example input of the JSON string:

{"fg":"yellow", "bg":"red"}

Note that you can also use json module to convert the JSON string as well.