I'm writing a program that will verify a username:
def user_login():
""" Login and create a username, maybe """
with open('username.txt', 'r') as f:
if f.readline() is "":
username = raw_input("First login, enter a username to use: ")
with open('username.txt', 'a+') as user:
user.write(username)
else:
login_id = raw_input("Enter username: ")
if login_id == str(f.readline()):
return True
else:
print "Invalid username."
return False
if __name__ == '__main__':
if user_login() is not True:
print "Failed to verify"
Everytime I run this it outputs the following:
Enter username: tperkins91
Invalid username.
Failed to verify
How do I compare user input to reading from a file?
Opening the same file again in another nested context is not a good idea. Instead, open the file once in append mode, and use f.seek(0) to return to the start whenever you need to:
def user_login():
""" Login and create a username, maybe """
with open('username.txt', 'a+') as f:
if f.readline() is "":
username = raw_input("First login, enter a username to use: ")
f.seek(0)
f.write(username)
# return True/False --> make the function return a bool in this branch
else:
login_id = raw_input("Enter username: ")
f.seek(0)
if login_id == f.readline():
return True
else:
print "Invalid username."
return False
if __name__ == '__main__':
if user_login() is not True:
print "Failed to verify"
Returning a bool value in the if branch is something you may want to consider so the return type of your function is consistent as bool, and not None as in the current case.
When you use readline() the first time the current file position is moved past the first record. A better way to find if the file is empty is to test it's size:
import os.path
import sys
def user_login():
fname = 'username.txt'
""" Login and create a username, maybe """
if os.path.getsize(fname) == 0:
with open(fname, 'w') as f:
username = raw_input("First login, enter a username to use: ")
f.write(username)
return True #/False --> make the function return a bool in this branch
else:
with open(fname, 'r') as f:
login_id = raw_input("Enter username: ")
if login_id == f.readline().rstrip():
return True
else:
print >>sys.stderr, "Invalid username."
return False
if __name__ == '__main__':
if user_login() is not True:
print "Failed to verify"
f.readline() will include a trailing newline, if there is one in the file, whereas raw_input() will not. While we don't explicitly write one, someone might edit the file and add a newline unintentionally, hence the addition of the rstrip() as a defensive precaution.
Related
import json
def write_json(data, file='users.json'):
with open(file, 'w') as f:
json.dump(data, f, indent=4)
while True:
user = {'name':[], 'password':[]}
choice = int(input('1) Register, 2) Login\n>> '))
if choice == 1:
username = input('Enter username: ')
password = input('Enter password: ')
user['name'] = username
user['password'] = password
print('Registered successfully')
with open('users.json') as json_file:
data = json.load(json_file)
users = data['users']
for user in users:
if user['name'] == username:
print(f'User "{username}" already exists')
break
new_user = user
users.append(new_user)
write_json(data)
if choice == 2:
username = input('Enter username: ')
password = input('Enter password: ')
with open('users.json', 'r') as f:
data = json.load(f)
for user in data['users']:
if user['name'] == username and user['password'] == password:
print('Logged in succesfully')
I am trying to make a simple login/register system, but when the user registers for the 2nd time, its gets overridden by the 1st key/value every time, I tried user.clear() but it doesnt seem to have an effect
The issue is that you are using a single dict item for all your users. The way you've set it up only allows for one user to exist.
You need to restructure your dict. You could do a list of dict items, but I would suggest using the username as the key in your dict. Since usernames are supposed to be unique, this makes sense IMHO.
In case you want to use the simpler list of dict items metioned above, you would structure it as follows:
[
{'Edo': 'mypassword'},
{'Iso': 'yourpassword'}
]
I've added some comments on the adjusted code below...
import json
def write_json(data, file="users.json"):
with open(file, "w") as outfile:
json.dump(data, outfile, indent=4)
def load_json(file="users.json"):
# try block in case file doesn't exist
try:
with open(file) as infile:
result = json.load(infile)
return result
except Exception as e:
# just printing out the error
print(e)
# should only be file not found error
# returning an empty dict
return {}
while True:
# you need to load before actually doing anything.
# if you don't you might overwrite the file
userlist = load_json()
# newlines for each option
choice = int(input("1) Register\n2) Login\n>> "))
if choice == 1:
username = input("Enter username: ")
# check if user already exists before requesting password
# since usernames are supposed to be unique, you can just
# create a dict with the key being username.
# you could use the value directly for password, but
# if you need to store more values for a user, I advice
# you use another dict as the value.
if username in userlist:
print(f"User {username} already exists")
# do some other magic here to handle this scenario
# continue makes the while loop go to the next iteration
continue
password = input("Enter password: ")
userlist[username] = {"password": password, "someotheruserdate": "dunno?"}
write_json(userlist)
# only print the success **after** you've actually
# completed all relevant logic.
print("Registered successfully")
# change this to elif instead of a second if statement
elif choice == 2:
username = input("Enter username: ")
password = input("Enter password: ")
if username in userlist and userlist[username]["password"] == password:
print("Logged in succesfully")
else:
# handle wrong username/password
# here you need to check after getting both username&password
print("Incorrect username/password combination")
So I'm making a program where I need a user to log in or register. The registered account goes to a .txt file from which I'm supposed to read the data to log in again.
I managed to get the basics working. I can register a new account to the file and I can log in with every account I've created, but I can't seem to get 2 important elements working. The first one is for when the user inserts an inexistent username/ password (in this case the program just does nothing as I can't figure out a condition to make it go back to asking the username and password), and the second one is for when I insert a username and password that don't match. Here the program goes back and asks for them again but then keeps asking, even if I put them correctly.
Here's my function if anyone's interested in having a look at it:
def ent():
util = False
ppass = False
login = False
while not login:
n_util = input("Introduce your username: ")
password = input("Introduce your password: ")
with open("dadoscontas.txt", "r") as f:
while not util:
vski = 0
for line in f:
vski += 1
if vski == 1:
if line.strip() == n_util:
util = True
else:
break
if vski == 2:
if line.strip() == password and user:
ppass = True
if user and ppass:
login = True
print("Logged in")
I've spent my whole afternoon trying different things to see if I can get these 2 things to work, but I can't. As I said, the function above is the part that kinda works, and if anyone could give any suggestions / point me in the right direction it would be really helpful. Thank you in advance.
Does this code cover your needs?
def ent():
util = False
login = False
while not login:
n_util = input("Introduce your username: ")
password = input("Introduce your password: ")
with open("some_test.txt", "r") as f:
vski = 0
for line in f:
vski += 1
if vski%2:
if line.strip() == n_util:
util = True
elif util:
if line.strip() == password:
login = True
else:
util = False
print("Logged in")
Or you even could exit the function with return in if line.strip() == password: block.
But i would recommend you to store the file content to dictionaries (user_name:passwor),
because you are parsing the whole file again and again while login=False:
def ent():
login = False
name=""
my_data = {}
with open("some_test.txt", "r") as f:
index = 0
for line in f:
index += 1
if index%2:
name = line.strip()
else:
my_data[name] = line.strip()
while not login:
n_util = input("Introduce your username: ")
password = input("Introduce your password: ")
if n_util in my_data and my_data[n_util] == password:
login = True
print("Logged in")
If you use python2 you can use .get() or try instead of n_util in my_data for better performance.
**This is a practice application
I have a text file containing a id & a password. Each pair is on separate lines like so:
P1 dogs
P2 tree
I then have 2 functions to allow the user the add another id/password or update the password by selecting an ID then the new password. (I have removed the save functionality so I don't create loads of pairs when testing)
The question is how would I write a check function so that when the user is creating a new pair.. it checks if the id/password already exists. Then on the update password function, it only checks if the password exists?
My code so far:
#Keyword check
def used_before_check(keyword, fname):
for line in open(fname, 'r'):
login_info = line.split()
username_found = False
for line in login_info:
if keyword in line:
username_found == True
if username_found == True:
return True
else:
return False
# New password function
def new_password():
print("\nCreate a new password")
new_id_input = input("Please give your new password an ID: ")
new_password_input = input("Please enter your new password: ")
print("ID in use?", used_before_check(new_id_input, txt_file))
print("Password in use?", used_before_check(new_password_input, txt_file))
#Change password function
def change_password():
print("\nChange password")
id_input = input("Enter the ID of the password you'd like to change: ")
password_input = input("Now enter the new password: ")
print("password_input",used_before_check(password_input, txt_file))
The easiest way would be to use JSON:
import json
import os
def new_password(user, password, password_dict={}):
if user in password_dict:
password_dict[user] = password # change password
else:
password_dict[user] = password # new password
return password_dict
def read_passwords(filename):
if not os._exists(filename):
return {}
with open(filename, 'r') as f:
s = f.read()
return json.loads(s)
password_filename = 'my_passwords.json'
password_dict = read_passwords(password_filename)
user = ''
while not user == 'q':
user = input('user:')
password = input('new password:')
if user != 'q':
password_dict = new_password(user, password, password_dict)
s = json.dumps(password_dict)
with open(password_filename, 'w') as f:
f.write(s)
Not that I have included a seemingly unnecessary if clause in new_password. This is just for you that you can easily enter your own code what you want to do (maybe different) in each case.
Create a function to store your usernames/passwords in a dictionary, then you can easily check it for existing usernames/passwords
To store in dictionary:
def process_file(fname):
username_pw_dict = {}
for line in open(fname, 'r'):
login_info = line.rstrip().split()
username = login_info[0]
pw = login_info[1]
username_pw_dict[username] = pw
return username_pw_dict
username_pw_dict = process_file(fname)
Then you can check for existing usernames or passwords like this:
if new_username in username_pw_dict:
print("username already exists")
if new_pw in username_pw_dict.values():
print("password already exists")
When you are reading the file, make a dictionary with all the IDs as its keys.
In next step, reverse the dictionary key-value pair so all its values (i.e all passwords) become its keys.
Finally, when you enter a new ID and password, just check those dictionaries to know if they already exist. You may refer to this below code:
dict_ids = {1 : "one", 2:"two", 3:"three"};
dict_pwds = {}
for key, value in dict_ids.items():
for string in value:
dict_pwds[value] = key;
print "dict_ids ", dict_ids;
print "dict_pwds ", dict_pwds;
if 'myid' in dict_ids.keys():
print "ID exist! "
else:
print "New ID"
if 'mypwd' in dict_pwds.keys():
print "Password exist! "
else:
print "New Password"
I am trying to make a login system that is looped basically and whenever I try to enter the correct details that are even stored in the .csv file, it outputs as incorrect username/password no matter what I put. This code works for python 3.6 but I need it to work for python 3.2.3.
loop1 = False #for this bit of code (logging in)
loop2 = False #for next bit of code
while loop1 == False:
choice = input("Login/SignUp [TYPE 'L' OR 'S']: ").lower()
if choice == "l":
username = input("Username: ")
password = input("Password: ")
f = open("usernamepassword.csv","r")
for line in f:
details = line.split(",")
if username == details[0] and password == details[1]:
print("Welcome")
break
#this whole bit of code is meant to read from the csv and check if the login details are correct
else:
print("Username/Password [INCORRECT]")
Allow me to refactor your code:
def login(username, password):
with open("usernamepassword.csv", "r") as csv:
all_details =
[[attr.strip() for attr in line.split(",")]
for line in csv]
return any(
username == details[0]
and password == details[1]
for details in all_details)
def login_action():
username = input("Username: ")
password = input("Password: ")
if not login(username, password):
raise ValueError("Username/Password [INCORRECT]")
return True
_USER_ACTIONS = {
'l': login_action
}
def main():
while True:
choice = input("Login/SignUp [TYPE 'L' or 'S']: ").lower()
action = _USER_ACTIONS[choice]
try:
if action():
break
except Exception as err:
print(err.message)
I think your unexpected behavior comes from not stripping the values you get after splitting by ,
Solved by replacing:
if username == details[0] and password == details[1]:
With:
if username == details[0] and (password+"\n") == details[1]:
You may have a bug in line.split(','), try line.strip().split(',')
TL; DR: posted a proper solution there : https://github.com/cgte/stackoverflow-issues/tree/master/47207293-csv-dict
I'll stuff up my answer later if needed.
Furthermore you have a poor code design here, and find yourself debugging in the middle of a loop.
So first of all : load the data file, store content to a dict.
f = open("usernamepassword.csv","r")
for line in f:
details = line.split(",")
if username == details[0] and password == details[1]:
print("Welcome")
break
Should become
user_pass = {}
f = open("usernamepassword.csv","r")
for line in f:
user, password = line.strip().split(",")
user_pass[user] = password
f.close()
or better
with open("usernamepassword.csv","r") as f:
for line in f.readlines():
user, password = line.split().split(",")
user_pass[user] = password
eventually run python -i yourfile.py and type "user_pass" to see what is actually stored when correct go on further code.
Think of using the csv module : https://docs.python.org/3/library/csv.html
Then get username and password from input and check:
if login in user_pass and user_pass[login] = password:
# or better `if user_pass.get(login, None) == password:`
do_stuff()
I'm using python 2.7.5 and i'm trying to make a simple program that has a username, password, and checks if it exists in a dictionary. If true, it prints welcome + username, and ignores if false.
First: code.
#!/usr/bin/python
import csv
users = {}
with open('C:\\Users\\chef\\Python\\fn.csv', 'wb') as f: # Just use 'w' mode in 3.x
w = csv.DictWriter(f, users.keys())
w.writeheader()
w.writerow(users)
def new_user():
uname = raw_input("Choose a username: ")
while 1:
pwd = raw_input("Choose a password: ")
check = raw_input("Retype password: ")
if pwd == check:
print "Saved."
users[uname] = pwd
break
if uname in users.keys():
pass
def show_users():
for unames in users.keys():
print unames
def login():
uname = raw_input("Username: ")
pwd = raw_input("Password: ")
if uname in users and pwd in users.values():
print "Welcome, " + uname + "! "
def save():
f=open('C:\\Users\\chef\\Python\\fn.csv', "wb")
w = csv.writer(f)
for key, val in users.items():
w.writerow([key, val])
f.close()
def read():
with open('C:\\Users\\chef\\Python\\fn.csv', 'wb') as f: # Just use 'w' mode in 3.x
w = csv.DictWriter(f, users.keys())
w.writeheader()
w.writerow(users)
print "Welcome to Yubin's 'fake' Email server."
while 1:
read()
choice = raw_input("What would you like to do? ")
if choice == "signup":
new_user()
if choice == "login":
login()
if choice == "showusers":
show_users()
if choice == "logout":
print "You have successfully logged out."
if choice == "quit":
x = raw_input("Are you sure? (y/n) ")
if x == "y":
save()
break
else:
pass
else:
print "Please sign up, log in or see who have signed up."
Problems:
When I first "sign up", i can log in perfectly fine. But, after closing the program and running it again, i can't log in. i assume it's because i set the dictionary empty every time i start, but it's supposed to rewrite the contents into the dictionary. i use windows 7 and in the preview, when i rerun the program, the file becomes empty.
After i write either login, signup or showusers, it prints the last line,
"Please sign up, log in or see who have signed up. "
Please i ask for solutions, and thank you in advance.
EDIT: I solved problem #2, but #1 still is there.
The problem is, as hyades stated, that your read-method overwrites the csv-file instead of reading it. The csv-module offers a reader for this purpose. I have changed your read-method like this to make it work:
def read():
with open('C:\\Users\\chef\\Python\\fn.csv', 'r') as f:
usersReader = csv.reader(f)
for row in usersReader:
if row == []:
pass
else:
users[row[0]] = row[1]
f.close();
You can also remove the "with open..."-code block at the begining of the file (after import and users-declaration).
For Problem 1, might be an issue with the mode of the file. Change it to wb+
Opens a file for both writing and reading in binary format. Overwrites
the existing file if the file exists. If the file does not exist,
creates a new file for reading and writing.
Problem 2 will be solved if you use if..elif instead of if
Check this code above. I use only save and read function. I used read function only once, outside while loop (used 'rb' mode istaed 'wb' mode). I used csv.WriteDict and csv.ReadDict classes enter link description here. to read and save data from users dict. I think You can use shelve or json instead csv, propobly these way will by faster and simply ;)
#!/usr/bin/python
import csv
users = {}
'''def write():
with open('/home/marcin/fn.csv', 'wb+') as f: # Just use 'w' mode in 3.x
w = csv.DictWriter(f, users.keys())
w.writeheader()
w.writerow(users)'''
def new_user():
uname = raw_input("Choose a username: ")
while 1:
pwd = raw_input("Choose a password: ")
check = raw_input("Retype password: ")
if pwd == check:
print "Saved."
users[uname] = pwd
break
if uname in users.keys():
pass
def show_users():
for unames in users.keys():
print unames
def login():
uname = raw_input("Username: ")
pwd = raw_input("Password: ")
if uname in users and pwd in users.values():
print "Welcome, " + uname + "! "
def save():
with open('/home/marcin/fn.csv', "wb+") as f:
fieldnames=['user','pwd']
writer = csv.DictWriter(f,fieldnames=fieldnames)
writer.writeheader()
for key, val in users.items():
writer.writerow({'user' : key, 'pwd' : val})
def read():
with open('/home/marcin/fn.csv','rb') as f: # Just use 'w' mode in 3.x
w = csv.DictReader(f)
for row in w:
print row
users[row['user']]=row['pwd']
def main():
print "Welcome to Yubin's 'fake' Email server."
try:
read()
except IOError:
pass
while 1:
choice = raw_input("What would you like to do? ")
if choice == "signup":
new_user()
save()
if choice == "login":
login()
if choice == "showusers":
show_users()
if choice == "logout":
print "You have successfully logged out."
if choice == "quit":
x = raw_input("Are you sure? (y/n) ")
if x == "y":
save()
break
else:
pass
else:
print "Please sign up, log in or see who have signed up."
if __name__ == "__main__":
main()