Adding placeholders to tkinter Entry widget in a procedural way

Question

I know this Q has been answered in this site, but im looking for a more simpler answer, and ive seen one before but then the question has been deleted or something, I cant find

Answer 1

Here is a very simple example. In this example we include a couple of features/caveats:

• ghost text for the placeholder
• entry.input will return None if it's text is the placeholder or empty
• entry.input should be used in place of .get() and .insert(). The .input logic is designed to give you the proper results for this type of widget. .get() is not smart enough to return the proper data, and .insert() has been reconfigured as a proxy to .input
• placeholder is juggled while you type
• placeholder can be overwritten with .insert() ~ no need to use .delete(). You should still use entry.input instead

---

#widgets.py

import tkinter as tk

class PlaceholderEntry(tk.Entry):
    '''
        All Of These Properties Are For Convenience
    '''
    @property
    def input(self):
        return self.get() if self.get() not in [self.__ph, ''] else None
        
    @input.setter
    def input(self, value):
        self.delete(0, 'end')
        self.insert(0, value)
        self.configure(fg = self.ghost if value == self.__ph else self.normal)
    
    @property
    def isempty(self) -> bool:
        return self.get() == ''
    
    @property     
    def isholder(self) -> bool:
        return self.get() == self.__ph
        
    def __init__(self, master, placeholder, **kwargs):
        tk.Entry.__init__(self, master, **{'disabledforeground':'#BBBBBB', **kwargs})
        
        self.normal = self['foreground']
        self.ghost  = self['disabledforeground']
        
        self.__ph = placeholder
        self.input = placeholder
        
        vcmd = self.register(self.validate)
        self.configure(validate='all', validatecommand=(vcmd, '%S', '%s', '%d'))
        
        self.bind('' , self.focusin)
        self.bind('', self.focusout)
        self.bind(''     , self.check)
    
    #rewire .insert() to be a proxy of .input
    def validate(self, action_text, orig_text, action):
        if action == '1':
            if orig_text == self.__ph:
                self.input = action_text
            
        return True
    
    #removes placeholder if necessary    
    def focusin(self, event=None):
        if self.isholder:
            self.input = ''
    
    #adds placeholder if necessary    
    def focusout(self, event=None):
        if self.isempty:
            self.input = self.__ph
    
    #juggles the placeholder while you type    
    def check(self, event):
        if event.keysym == 'BackSpace':
            if self.input and len(self.input) == 1:
                self.input = self.__ph
                self.icursor(0)
                return 'break'
        elif self.isholder:
            if event.char:
                self.input = ''
            else:
                return 'break'

---

usage example:

#__main__.py

import tkinter as tk
import widgets as ctk #custom tk                
                

if __name__ == "__main__":
    root = tk.Tk()
    root.title("Placeholder Entry")
    root.grid_columnconfigure(2, weight=1)

    #init some data
    entries    = [] #for storing entry references
    label_text = ['email', 'name']
    entry_text = ['you@mail.com', 'John Smith']

    #create form
    for n, (label, placeholder) in enumerate(zip(label_text, entry_text)):
        #make label
        tk.Label(root, text=f'{label}: ', width=8, font='consolas 12 bold', anchor='w').grid(row=n, column=0, sticky='w')
        #make entry
        entries.append(ctk.PlaceholderEntry(root, placeholder, width=14, font='consolas 12 bold'))
        entries[-1].grid(row=n, column=1, sticky='w')

    #form submit function
    def submit():
        for l, e in zip(label_text, entries):
            if e.input:
                print(f'{l}: {e.input}')

    #form submit button        
    tk.Button(root, text='submit', command=submit).grid(column=1, sticky='e')

    root.mainloop()