Changing entry box background colour in tkinter - python-3.x

Question

So I've been working on this program and I'm finding it very hard to figure out what's wrong. I'm fairly new to tkinter so this may be quite minor.
I'm trying to get the program to change the entry box's background colour when the check button is pressed. Or even better if somehow I can change it dynamically it would be even better.
This is my code at the moment:
TodayReading = []
colour = ""
colourselection= ['green3', 'dark orange', "red3"]
count = 0
def MakeForm(root, fields):
entries = []
for field in fields:
row = Frame(root)
lab = Label(row, width=15, text=field, font=("Device",10, "bold"), anchor='center')
ent = Entry(row)
row.pack(side=TOP, padx=5, fill=X, pady=5)
lab.pack(side=LEFT)
ent.pack(side=RIGHT, expand=YES, fill=X)
entries.append((field, ent))
return entries
def SaveData(entries):
import time
for entry in entries:
raw_data_point = entry[1].get()
data_point = (str(raw_data_point))
TodayReading.append(data_point)
c.execute("CREATE TABLE IF NOT EXISTS RawData (Date TEXT, Glucose REAL, BP INTEGER, Weight INTEGER)")
c.execute("INSERT INTO RawData (Date, Glucose, BP, Weight) VALUES (?, ?, ?, ?)", (time.strftime("%d/%m/%Y"), TodayReading[0], TodayReading[1] , TodayReading[2]))
conn.commit()
conn.close()
def DataCheck():
if ((float(TodayReading[0])>=4 and (float(TodayReading[0])<=6.9))):
colour = colourselection[count]
NAME OF ENTRY BOX HERE.configure(bg=colour)
Thanks for the help. Someone may have answered it already but like i said I'm new to tkinter so if i've seen it already, I haven't figured out how to implement it.

Answer 1

Please see my example below:
from tkinter import *
class App:
def __init__(self, root):
self.root = root
self.var = StringVar() #creates StringVar to store contents of entry
self.var.trace(mode="w", callback=self.command)
#the above sets up a callback if the variable containing
#the value of the entry gets updated
self.entry = Entry(self.root, textvariable = self.var)
self.entry.pack()
def command(self, *args):
try: #trys to update the background to the entry contents
self.entry.config({"background": self.entry.get()})
except: #if the above fails then it does the below
self.entry.config({"background": "White"})
root = Tk()
App(root)
root.mainloop()
So, the above creates an entry widget and a variable which contains the contents of that widget.
Every time the variable is updated we call command() which will try to update the entry background colour to the contents of the entry (IE, Red, Green, Blue) and except any errors, updating the background to White if an exception is raised.
Below is a method of doing this without using a class and using a separate test list to check the value of the entry:
from tkinter import *
root = Tk()
global entry
global colour
def callback(*args):
for i in range(len(colour)):
if entry.get().lower() == test[i].lower():
entry.configure({"background": colour[i]})
break
else:
entry.configure({"background": "white"})
var = StringVar()
entry = Entry(root, textvariable=var)
test = ["Yes", "No", "Maybe"]
colour = ["Red", "Green", "Blue"]
var.trace(mode="w", callback=callback)
entry.pack()
root.mainloop()