How can I make a Tkinter GUI that auto fills certain entries

Question

I am trying to make a GUI with Tkinter that allows you to enter either a URL or an ID.

Example URL: https://www.fanfiction.net/s/10030860/1/The-Final-Battle Example ID: 10030860

As you can see, the ID is embedded in the URL. I want to have two entries, one for entering a URL and one for entering an ID. If a user fills in the URL box, the ID is automatically generated. (If I put the example URL in the URL entry box, I want the example ID in the ID box automatically generated and vice versa) If a user fills in the ID box, the URL is automatically generated.

More examples: (The brackets are pretending to entry boxes)

URL: [https://www.fanfiction.net/s/10030860/1/The-Final-Battle] <-- If I fill this in
ID:  [10030860] <-- Python fills this in for me

URL: [https://www.fanfiction.net/s/10030860/1/The-Final-Battle] <-- Python fills this in for me
ID:  [10030860] <-- If I fill this in

Here is my code so far:

import tkinter as tk
from tkinter import ttk

# Define a function to autofill in the URL and ID entries
def autofill_id_url():
    fanfic_url.set("https://www.fanfiction.net/s/" + fanfic_id.get() + "/1/")
    root.after(100, autofill_id_url)

# Root window
root = tk.Tk()

# Define the labeled frame where we input stuff
input_frame = tk.LabelFrame(master=root, text="Input")
input_frame.grid(row=0, column=0, padx=1, pady=1, rowspan=2, sticky=tk.NS)

# Label for entering URL
ttk.Label(master=input_frame, text="URL:").grid(row=0, column=0, padx=1, pady=1)
# Entry field for URL
fanfic_url = tk.StringVar()
url_entry = ttk.Entry(master=input_frame, textvariable=fanfic_url)
url_entry.grid(row=0, column=1, padx=1, pady=1)

# Label for entering ID
ttk.Label(master=input_frame, text="ID:").grid(row=1, column=0, padx=1, pady=1)
# Entry field for ID
fanfic_id = tk.StringVar()
id_entry = ttk.Entry(master=input_frame, textvariable=fanfic_id)
id_entry.grid(row=1, column=1, padx=1, pady=1)

# Start callback functions
autofill_id_url()

# Start GUI event loop
root.mainloop()

I have the part when you fill in the ID, the URL is generated automatically. But I have no idea how to make it when you fill in the URL box, you get the ID box filled in for you.

Thanks in advance.

Answer 1

Better do the auto fill when Enter key is pressed in the entry box instead of using .after().

baseurl = 'https://www.fanfiction.net/s/'

def autofill_url_id(_):
    try:
        # extract the id from the url
        url = fanfic_url.get().strip()
        if url.startswith(baseurl):
            id = url.split('/')[4]
            fanfic_id.set(id)
    except IndexError:
        print('failed to extract id from the url')

def autofill_id_url(_):
    id = fanfic_id.get().strip()
    if id:
        fanfic_url.set(baseurl+id+'/1/')
...
# Start callback functions
#autofill_id_url()
url_entry.bind('<Return>', autofill_url_id)
id_entry.bind('<Return>', autofill_id_url)

Answer 2

You can use the trace_variable method of StringVar to do autofill. The following code will do so but this is just a basic code to get started as it will require some more work to implement autofill perfectly.

after_ids = {}

def get_url(id_):
    """returns url from id."""
    url = 'https://www.fanfiction.net/s/{}/1/The-Final-Battle'
    return url.format(id_)

def get_id(url):
    """returns id from the url."""
    l = url.split('/')
    return l[4] if len(l) > 4 else ''

def autofill_entry(mode, dalay=1000):
    """Auto-fills Url/ID."""
    for v in after_ids.values():
        root.after_cancel(v)
    if mode == 'url':  
        id_ = get_id(fanfic_url.get())
        after_ids[0] = root.after(dalay, lambda: fanfic_id.set(id_))
    elif mode == 'id':
        url = get_url(fanfic_id.get())
        after_ids[1] = root.after(dalay, lambda: fanfic_url.set(url))

Now assign the function autofill_entry to the entry widgets StringVars.

fanfic_url.trace_variable('w', lambda *a: autofill_entry('url'))
fanfic_id.trace_variable('w', lambda *a: autofill_entry('id'))

Also, I would recommend you use from urllib.parse import urlparse, parse_qs to join URL and fetch id from the URL.