Several input data such as date, time, phone number, credit card number, website URL, IP number, and so on have an associated display format. For instance, date is better represented in a MM/DD/YYYY format.
Fortunately, it is easy to format the data in the required format as the user enters them in the widget (refer to 8.07 formatting entry widget to display date.py). The mentioned Python file formats the user input automatically to insert forward slashes at the required places to display user-entered date in the MM/DD/YYYY format.
from Tkinter import *
class FormatEntryWidgetDemo:
def __init__(self, root):
Label(root, text='Date(MM/DD/YYYY)').pack()
self.entereddata = StringVar()
self.dateentrywidget =Entry(textvariable=self.entereddata)
self.dateentrywidget.pack(padx=5, pady=5)
self.dateentrywidget.focus_set()
self.slashpositions = [2, 5]
root.bind('<Key>', self.format_date_entry_widget)
def format_date_entry_widget(self, event):
entrylist = [c for c in self.entereddata.get() if c != '/']
for pos in self.slashpositions:
if len(entrylist) > pos:
entrylist.insert(pos, '/')
self.entereddata.set(''.join(entrylist))
# Controlling cursor
cursorpos = self.dateentrywidget.index(INSERT)
for pos in self.slashpositions:
if cursorpos == (pos + 1): # if cursor is on slash
cursorpos += 1
if event.keysym not in ['BackSpace', 'Right', 'Left','Up', 'Down']:
self.dateentrywidget.icursor(cursorpos)
root = Tk()
FormatEntryWidgetDemo(root)
root.mainloop()The description of the preceding code is as follows:
- The Entry widget is bound to the key press event, where every new key press calls the related callback
format_date_entry_widgetmethod. - First, the
format_date_entry_widgetmethod breaks down the entered text into an equivalent list by the nameentrylist, also ignoring any slash'/'symbol if entered by the user. - It then iterates through the
self.slashpositionslist and inserts the slash symbol at all required positions in theentrylistargument. The net result of this is a list that has slash inserted at all the right places. - The next line converts this list into an equivalent string using
join(), and then sets the value of our Entry widget to this string. This ensures that the Entry widget text is formatted into the aforementioned date format. - The remaining pieces of code simply control the cursor to ensure that the cursor advances by one position whenever it encounters a slash symbol. It also ensures that key presses, such as
'BackSpace','Right','Left','Up', and'Down'are handled properly.
Note that this method does not validate the date value and the user may add any invalid date. The method defined here will simply format it by adding forward slash at third and sixth positions. Adding date validation to this example is left as an exercise for you to complete.
This concludes our brief discussion on formatting data within widgets. Hopefully, you should now be able to create formatted widgets for a wide variety of input data that can be displayed better in a given format.