Question

So I’ve been trying to make some basic GUIs with tkinter (not te be confused with Tkinter) and I ran into a problem for which I know no solution and can’t really find anything on the almighty Google…
I have a small SQLite database with a table of directories on my pc. I would like to draw all directorypaths into a label and add a ‘rempve’ button next to that label. The button should be able to remove directory from the database and also remove it from the GUI. I also have a ‘add’ button where one can add directories to the database and this new directory should be shown in the GUI. This is my basic layout:

---------------
| ADD         |
|dir1   REMOVE|
|dir2   REMOVE|
---------------

I use the gridlayout to show the buttons and labels. Most things work, all database related stuff works. Also when starting the GUI the current directories and ‘remove’-buttons are shown nicely. BUT… when using the ‘remove’ button the directory does not disappear from the GUI even though it is not in the database anymore, restarting the GUI fixes it of course. Adding a label works… but I’m not sure if I’m doing it correctly…
How can I somehow ‘repaint’ the GUI with the new information?
This is my code for the GUI:

class GUI():

def __init__(self,db):
    self.root = Tk()
    self.root.title("Example")
    self.frame = ttk.Frame(self.root, padding="3 3 12 12")
    self.frame.rowconfigure(5, weight=1)
    self.frame.columnconfigure(5, weight=1)
    self.frame.grid(sticky=W+E+N+S)

    lbl = ttk.Label(self.frame, text="", width=17)
    lbl.grid(row=0, column=2, sticky=W)
    ttk.Button(self.frame, text="Add directory", command=lambda:self.load_file(db), width=30).grid(row=0, column=0, sticky=W, padx=(500,50))
    ttk.Button(self.frame, text="Sort files", command=lambda:self.sort(db,lbl), width=17).grid(row=0, column=1, sticky=W)
    self.draw(db)
    self.root.mainloop()

def load_file(self,db):
    fname = filedialog.askdirectory()
    db.addPath(fname)
    self.draw(db)

def remove_dir(self,db,pid):
    db.removePath(pid)
    self.draw(db)

def sort(self,db,lbl):
    lbl['text'] = 'Sorting...'
    sortFiles.moveFiles(db)
    lbl['text'] = 'Done!'


def draw(self,db):
    i = 0
    paths = db.getPaths()
    for path in paths:
        ttk.Label(self.frame,text=path[1]).grid(row=1+i,column=0,sticky=W)
        ttk.Button(self.frame, text="Remove directory", command=lambda:self.remove_dir(db,path[0]), width=17).grid(row=1+i,column=1, sticky=E)
        i = i+1
    for child in self.frame.winfo_children(): child.grid_configure(padx=5, pady=5)
    if i == 0:
        ttk.Label(self.root,text='No directories added yet').grid(row=1,column=0,sticky=W)

Answer 1

If you prefer to redraw the GUI every time you add or delete something, you need to first destroy any old widgets before creating new ones. For example:

def draw(self, db):
    # first, delete any existing widgets
    for child in self.frame.winfo_children():
        child.destroy()
    # next, redraw all the widgets
    paths = db.getPaths()
for path in paths:
        ...

You have another bug, which is how you’re using lambda. As it stands with the code in the question, all of your callbacks will see the same value. By specifying the value as a keyword argument to the lambda you’ll get the right value:

ttk.Button(..., command=lambda p=path[0]:self.remove_dir(db, p)...)

Unrelated to the actual problem, I don’t think you need to be passing db around. Assuming you only use a single db, I recommend you do self.db = db in your GUI constructor. That will make your code just a little easier to maintain because your method signatures will be simplified.

Finally, there’s really no need to completely redraw the GUI when you delete one item. You can delete just one label and button at a time. This requires that you spend a little more time thinking about how you manage data in your program. If, for example, you keep a reference to each label and button, you can delete it when you delete the path from the database. Your removeDir function might look something like:

def removeDir(self, pid):
    label, button = self.widgets(pid)
    label.destroy()
    button.destroy()