How to get the values of all the OptionMenu widgets within a frame inside a canvas in Tkinter - python-3.x

Question

I'm writing a minimalist image tagging app that will list out all the image files in a specific location alongside a dropdown menu to select the options for tagging the image. Once the images are tagged, I need to save the changes to a JSON file and I've got a button for that. How can we read all the options selected so that it can be written into a file?
Following is the code so far:
from tkinter import N, RIGHT, Button, OptionMenu, Scrollbar, StringVar, Tk, Canvas, Frame, Label
class App:
def __init__(self):
self.root = Tk()
self.tags = ['Apples', 'Oranges', 'Berries']
self.GetRows()
self.SaveButton()
self.root.mainloop()
def GetRows(self):
self.canvas = Canvas(self.root)
self.scroll_y = Scrollbar(self.root, orient="vertical", command=self.canvas.yview)
self.frame = Frame(self.canvas)
lst = [f"A01{str(i)}.JPG" for i in range(100)]
for idx, r in enumerate(lst):
filename = Label(self.frame, text=r)
filename.grid(row=idx+2, column=0, sticky=N)
label = StringVar()
drop = OptionMenu(self.frame, label, *self.tags)
drop.grid(row=idx+2, column=1)
# put the frame in the canvas
self.canvas.create_window(0, 0, anchor='nw', window=self.frame)
# make sure everything is displayed before configuring the scrollregion
self.canvas.update_idletasks()
self.canvas.configure(scrollregion=self.canvas.bbox('all'),
yscrollcommand=self.scroll_y.set)
self.canvas.pack(fill='both', expand=True, side='left')
self.scroll_y.pack(fill='y', side='right')
def SaveState(self):
pass
def SaveButton(self):
self.save_button = Button(self.root, text="Save Changes", padx=50, pady=10, command=self.SaveState)
self.save_button.pack(side=RIGHT)
if __name__ == '__main__':
App()
The SaveState method is what will be used to write the selections so far into a file.
Thanks in advance!

Answer 1

In order to make OptionMenu results available try modifying your code so that
all StringVars are accessible outside of GetRows.
def GetRows(self):
...
# Define label as a list
self.label = []
for idx, r in enumerate(lst):
filename = Label(self.frame, text=r)
filename.grid(row=idx+2, column=0, sticky=N)
label = StringVar()
drop = OptionMenu(self.frame, label, *self.tags)
drop.grid(row=idx+2, column=1)
# Save StringVar reference
self.label.append(label)
...
def SaveState(self):
self.data = dict()
# Retrieve results into dictionary
for i, a in enumerate(self.label):
self.data[f"A_{i}"] = a.get()
print(self.data)
Then use json.dump(self.data, a_file) to save it