Dynamically add columns in Tkinter treeview

Question

The program is supposed to add columns dynamically in order to present more data when corresponding button is pressed. The buttons can be pressed in different order and that effects the appearance of the next column/header. As you can see in the example program, the headers are not updated correctly. Only the last one is shown in the table. If the item (selected row and column) already has data, it should be updated, but currently the data is added only in new column, so one of the questions is how to update an item referred by selected row and header. When the row is deleted, all empty columns should be removed. I'm trying to update the columns by concatenating tuples, but have no idea how to deal with the headers. Any suggestions are very appreciated.

from random import randint
from tkinter import *
from tkinter.ttk import Treeview


def get_window():
    root = Tk()
    root.resizable(width=True, height=True)
    root.geometry("823x458")
    root.title("PsControl")
    return root


def get_top_frame(root):
    frame = Frame(root)
    frame.name = 'top_frame'

    frame.root = root

    frame.pack(side=TOP, expand=False, fill=X)

    button1 = Button(frame, text="Add Row", command=lambda: tv.insert('', 'end', text="hostname"))
    button1.grid(row=0, column=1)

    button1 = Button(frame, text="Add Cow 1", command=lambda: tv_insert("H1", randint(1, 100)))
    button1.grid(row=0, column=2)

    button2 = Button(frame, text="Add Cow 2", command=lambda: tv_insert("H2", randint(1, 100)))
    button2.grid(row=0, column=3)

    button3 = Button(frame, text="Add Cow 3", command=lambda: tv_insert("H3", randint(1, 100)))
    button3.grid(row=0, column=4)

    button4 = Button(frame, text="Add Cow 20", command=lambda: tv_insert("H4", randint(1, 100)))
    button4.grid(row=0, column=5)

    button5 = Button(frame, text="Delete row", command=lambda: tv.delete(tv.selection()))
    button5.grid(row=0, column=6)


def get_bottom_frame(root):
    global tv
    frame = Frame(root, highlightbackground='#3E4149', highlightthickness=1, borderwidth=2)
    frame.name = 'bottom_frame'
    frame.root = root

    h = Scrollbar(root, orient='horizontal')
    h.pack(side=BOTTOM, fill=X)
    v = Scrollbar(root)
    v.pack(side=RIGHT, fill=Y)

    frame.pack(side=BOTTOM, expand=True, fill=BOTH)
    frame.config(background='#FFFFFF')

    tv = Treeview(frame, xscrollcommand=h.set, yscrollcommand=v.set)

    tv.column("#0", width=135, minwidth=35, stretch=NO)
    tv.heading("#0", text='Host', anchor='w')

    tv.pack(expand=True, fill='both')

    h.config(command=tv.xview)
    v.config(command=tv.yview)


def tv_insert(heading, insert_data):
    selection = tv.selection()
    columns = tv["columns"]

    if columns == '':
        tv["columns"] = (heading,)
        tv.column(heading, width=135, minwidth=35, stretch=NO)
        tv.heading(heading, text=heading, anchor='w')
        tv.item(selection, values=insert_data)
    else:
        new_col = columns + (heading,)
        tv["columns"] = new_col

        tv.heading(heading, text=heading, anchor='w')

        data = tv.item(selection, "values")
        if data == '':
            tv.item(selection, values=insert_data)
        else:
            new_data = data + (insert_data,)
            tv.item(selection, values=new_data)


def delete_row():
    selection = tv.selection()
    tv.delete(selection)


root = get_window()
get_top_frame(root)
get_bottom_frame(root)

root.mainloop()

Thanks to @acw1668 answer here is the code that does the job as expected. Any suggestions for improvement are welcome.

def tv_insert(heading, insert_data):
    selection = tv.selection()
    columns = tv["columns"]
    if columns == '':  # if no columns, create column, heading and item.
        tv["columns"] = (heading,)
        tv.column(heading, width=135, minwidth=35, stretch=NO)
        tv.heading(heading, text=heading, anchor='w')
        tv.item(selection, values=(insert_data,))
    else:
        headings = [tv.heading(col) for col in columns] # save current headings

        if heading not in columns:
            new_col = columns + (heading,)
            tv["columns"] = new_col
            # restore previous headings
            for h in headings:
                tv.heading(h['text'], text=h['text'], anchor=h['anchor'])
            # set new heading
            tv.heading(heading, text=heading, anchor='w')
            # add data/item with with size of the columns
            len_col = len(new_col)
            data = ['' for _ in range(len_col)]    # Create an empty list
            data[len_col - 1] = insert_data                # Update the next
            tv.item(selection, values=tuple(data))

        else:
            data = tv.item(selection, "values")
            # if heading exist but no item on the the selected row
            if data == '':
                data = ['' for _ in range(len(headings))]
                index = columns.index(heading)
                data[index] = insert_data
                tv.item(selection, values=tuple(data))
            else:
                data = list(data)
                if len(data) < len(columns):
                    new_data = ['' for _ in range(len(columns))]
                    for i, d in enumerate(data):
                        new_data[i] = d
                    index = columns.index(heading)
                    new_data[index] = insert_data
                    tv.item(selection, values=tuple(new_data))
                else:
                    index = columns.index(heading)
                    data[index] = insert_data
                    tv.item(selection, values=tuple(data))

Answer 1

Since you have assigned new columns to tv , the headings information is lost. You should save the current headings information before assigning the new columns and restore them after:

def tv_insert(heading, insert_data):
    selection = tv.selection()
    columns = tv["columns"]

    if columns == '':
        tv["columns"] = (heading,)
        tv.column(heading, width=135, minwidth=35, stretch=NO)
        tv.heading(heading, text=heading, anchor='w')
        tv.item(selection, values=insert_data)
    else:
        headings = [tv.heading(col) for col in columns] # save current headings
        new_col = columns + (heading,)
        tv["columns"] = new_col

        # restore previous headings
        for h in headings:
            tv.heading(h['text'], text=h['text'], anchor=h['anchor'])
        # set new heading
        tv.heading(heading, text=heading, anchor='w')

        data = tv.item(selection, "values")
        if data == '':
            tv.item(selection, values=insert_data)
        else:
            new_data = data + (insert_data,)
            tv.item(selection, values=new_data)