How can I update Entry without a “submit” button in Tkinter?

问题

So I have Entries which have some values assigned to them from a CFG File. I want to modify the CFG file when the Entry is updated, live, without a submit button;

Using <Key> binding will work but will take only the previous value, not the current one, as the last key pressed is not taken into consideration as a value, but as a key-press.

For example:

class EntryBox:
    def __init__(self, value, option, section, grid_row, master_e):
        self.section = section
        self.option = option
        self.box = Entry(master_e)
        self.box.grid(column=0, row=grid_row)
        self.serial_no = grid_row
        self.box.insert(0, value)
        self.box.bind("<Key>", lambda event: update_cfg(event, self, self.get_value()))

    def get_value(self):
        return self.box.get()


    def update_cfg(evt, entry_box,new_value):
        global config_file
        config_file.set(entry_box.section, entry_box.option, new_value)
        print "Config file modified. "+entry_box.section+" "+entry_box.option+" "+new_value

If the value in the entry is 05R when I click on the entry and press 6, it will print Config file modified. CURRENT_MEASUREMENT_EXAMPLE_HP shunt_resistance 05R; after I press 7, it will print Config file modified. CURRENT_MEASUREMENT_EXAMPLE_HP shunt_resistance 0R56 and so on, always with one keypress behind. The only way to live update it after the value has been changed is to press the TAB or arrow buttons.

回答1:

You can use either

• FocusOut
• tab or enter Key
• KeyRelease

bindings to achieve that.

Also validation functions can help as they have previous and new values available. Please read the docs for more information on that matter.

It is IMHO the most "pythonic" / "tkinter" way of achieving what is a "check and submit" functionality.

Edit

As stated by OP, binding focusout could lead to problems here an example how it does indeed work:

import Tkinter as tk
import sys

def focus_out_event(event):
    print >> sys.stderr, "Focus-Out   event called with args: %s"%event
    print >> sys.stderr, "Entry Widget Content:               %s"%event.widget.get()
def key_release_event(event):
    print >> sys.stderr, "Key-Release event called with args: %s"%event
    print >> sys.stderr, "Entry Widget Content:               %s"%event.widget.get()

if __name__ == "__main__":
    root = tk.Tk()
    entry1 = tk.Entry(root)
    entry1.bind("", key_release_event)
    entry1.bind("", focus_out_event)
    entry1.grid()

    entry2 = tk.Entry(root)
    entry2.bind("", key_release_event)
    entry2.bind("", focus_out_event)
    entry2.grid()

    root.mainloop()

Test: - enter text ("asd") to entry1 - click into entry2

The last line of output is from changing to screenshot (event that fired a focusout)

回答2:

You have this key-press in event.char so you can add it to text.

回答3:

I decided that <Key> was not the right option in my case and instead used <FocusOut>. This way, if you either change the value using the mouse or keyboard TAB, on focus out it will update it.

来源：https://stackoverflow.com/questions/39957699/how-can-i-update-entry-without-a-submit-button-in-tkinter