validate input in command line in python

Question

I'm trying to create a login panel in the command line using python. so if the user does not insert any username, the cursor should remain on the same line but I should get an error on the next line.

I tried:

while True:
  input1  = input('username: ')
  if len(input1) == 0:
    print("Sorry, your response was not loud enough.")
    continue

  input2 = stdiomask.getpass('pasword: ')
  if len(input2) == 0:
    print("Sorry, your response was not loud enough.")
    continue

  input3 = stdiomask.getpass('cnf password: ')
  if len(input3) == 0:
    print("Sorry, your response was not loud enough.")
    continue

But since I'm using while loop so if I'm not inserting password I have to insert username again which I don't want also if I don't insert a username, the username is prompted on next line after showing error. so Is there any way to handle these situations?

something like this:

F:\new_file\file> python main.py
? username: # cursor remains here until a username is inserted
> Invalid input # error is prmpted on next line

try to use recursion, posted sample code

Suryaveer Singh
– Suryaveer Singh

2020-08-26 08:38:49 +00:00
Commented Aug 26, 2020 at 8:38 — Suryaveer Singh
– Suryaveer Singh, Commented Aug 26, 2020 at 8:38

Suryaveer Singh · Accepted Answer · 2020-08-26 11:53:53Z

1

Try recursion to get input and check if valid. If it is valid then return input else call the same function again

def get_input(name, reset=0):
  if reset:
    print(end=f"> Invalid {name}\r", flush=True)
    print(f"\b", end=f"\r{name}: ", flush=True)
  else:
    print(f"{name}: \b", end=f"\r{name}: ", flush=True)
   
  inp = input()
  if len(inp)==0:
    inp = get_input(name, reset=1)
  return inp
input1=get_input('username')
input2=get_input('pasword')
input3=get_input('cnf password')

edited Aug 26, 2020 at 11:53

answered Aug 26, 2020 at 8:27

Suryaveer Singh

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3 Comments

Zodiac Over a year ago

Thanks, It worked but Is it possible to write input on the same line, i.e if no input is passed, the error is popped on the next line but the cursor remains at the same line and waits for the user to write input.

Suryaveer Singh Over a year ago

added reset logic in answer. check correct if you find it correct

Zodiac Over a year ago

Still coming on next line.

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