combobox value is not selecting in python when it is created dynamically - python-2.7

Question

I created a Tkinter window Form, in that based on user selection i dynamically replace the combobox with deleting the Exist one.But the Problem is when i do like this the value selected in combobox is not updated.It is always displaying the default vale. see the following code
from Tkinter import *
import ttk
final=[]
field_0=['1','0']
field_1=['1','2','23','45','6']
field_2=['2','5','7','8','9']
class header:
def __init__(self,root):
self.parent=root
self.row_number= 1
self.value=0
root.title(" Select fields ")
root.minsize(width=450, height=530)
root.maxsize(width=450, height=550)
frame=Frame(root,height=20,relief=FLAT)
frame.grid(row=0,column=0,sticky=W)
Label(frame,text="Enter value:").grid(row=0,column=0,padx=70,pady=5,sticky=W)
entryValue=StringVar()
port_e = Entry(root,width=5,textvariable=entryValue)
port_e.delete(0,END)
port_e.insert(0,'0')
port_e.grid(row=0,column=0,padx=100,pady=5)
self.value=self.value+1
self.change_row=self.row_number
self.combocreate(self.change_row,root,field_0)
self.change_row=self.change_row+1
self.combocreate(self.change_row,root,field_1)
def combocreate(self,row_number,msg_frame,field):
comboBoxValue = [] # 'request'command for sink only
self.box_value=StringVar()
self.combo=ttk.Combobox(root,textvariable=self.box_value,state='readonly')
self.combo['values'] = tuple(field)
self.combo.set(field[1])
self.combo.grid(row = row_number, column = 1)
self.combo.bind("<<ComboboxSelected>>",self.selected_field)
final.append(self.combo)
def selected_field(self,event):
global cnt_sel
print final[0].get()
if(final[0].get()=='1'):
self.control=Label(root,text="Choose one type").grid(row=self.change_row,column=0,padx=20,pady=5,sticky=W)
self.combocreate(self.change_row,root,field_1)
final[1]=final[2] #replacing combobox dynamically based on selection
del final[2]
elif(final[0].get()=='0'):
Label(root,text="Choose zerotype ").grid(row=self.change_row,column=0,padx=20,pady=5,sticky=W)
self.combocreate(self.change_row,root,field_2)
final[1]=final[2]
del final[2]
else:
pass
if __name__=="__main__":
root=Tk()
app=header(root)
root.mainloop()

Answer 1

The problem with your code is that every time combocreate is called, it automatically binds the Combobox to self.selected_field, so whenever you change the value of the type Combobox, you call self.selected_field, and it automatically resets the type to the default. To fix the problem, you should only bind the first Combobox. This should fix the problem:
Replace
self.change_row=self.row_number
self.combocreate(self.change_row,root,field_0)
self.change_row=self.change_row+1
self.combocreate(self.change_row,root,field_1)
With
self.change_row=self.row_number
self.combocreate(self.change_row,root,field_0)
final[0].bind("<<ComboboxSelected>>",self.selected_field)
self.change_row=self.change_row+1
self.combocreate(self.change_row,root,field_1)
And
def combocreate(self,row_number,msg_frame,field):
comboBoxValue = [] # 'request'command for sink only
self.box_value=StringVar()
self.combo=ttk.Combobox(root,textvariable=self.box_value,state='readonly')
self.combo['values'] = tuple(field)
self.combo.set(field[1])
self.combo.grid(row = row_number, column = 1)
self.combo.bind("<<ComboboxSelected>>",self.selected_field)
final.append(self.combo)
With
def combocreate(self,row_number,msg_frame,field):
comboBoxValue = [] # 'request'command for sink only
self.box_value=StringVar()
self.combo=ttk.Combobox(root,textvariable=self.box_value,state='readonly')
self.combo['values'] = tuple(field)
self.combo.set(field[1])
self.combo.grid(row = row_number, column = 1)
final.append(self.combo)