Tkinter: AttributeError: 'Entry' object has no attribute 'curselection'

I am trying to add a mark when i click on mark complete button, but i received error whenever i click.

from tkinter import *
from tkinter import ttk
def markcompleted():
    marked=task_field.curselection()
    temp=marked[0]
#store the text of selected item in a string
    temp_marked=task_field.get(temp)
#update it 
    temp_marked=f'{temp_marked} {" ✔ "}'
#delete it then insert it 
    task_field.delete(temp)
    task_field.append('end',temp,temp_marked)