如何每次创建一个唯一的字母数字 id 并确保它不存在于我使用 python 的现有列表中？

Question

I need to assign a unique name that contains the word 'user' and a certain random numbers to a user. Something like user32944 , user80890 etc. So I write a program something like this

import random

user_list = ["user32944", "user60690"] # essentially this list is what I retrieve from some database
user_name = ""
while(True):
    if user_name not in user_list:
        user_name = "user" + str(random.random() * 100000).split(".")[0]
        break

print(user_name)

But if I deliberately set the user_name to something that already exists in the list, my program doesn't exit the loop and the program hangs.

What am I doing wrong?

Answer 1

You only perform a action when the generated username is not in the list, but you don't do anything when the username is in the list. And therefore you don't exit the while loop and the program will hang.

The following code sample does what you want. Although i recommend you to explore the uuid package in python.

import random
user_list = ["user32944", "user60690"] # essentially this list is what I retrieve from some database

def generateRandomUsername():
    randomNr = random.randint(1,3)
    if randomNr == 1:
        return "user32944"
    else:
        return "user" + str(random.random() * 100000).split(".")[0]

def getRandomUniqueUsername():
    while(True): 
        username = generateRandomUsername() 
        if username not in user_list:
            print('Created user \'%s\'' % username) 
            return username
        else:
            print("Username \'%s\'already exists, generating new one" % username)

def printUsernameList():
    for username in user_list:
        print('Username: %s' % username)

#Create 4 random usernames
for i in range(4):
    username = getRandomUniqueUsername()
    user_list.append(username)
    print('Printing user_list...')
    printUsernameList()

Answer 2

That will never exit the loop because you are never satisfying the IF condition and there is no conditional expression on while too, you gave True in while condition -> which means it loops infinitely.

So if you do not satsifying the IF condition then write a logic what you would want to do incase IF does not get statisified and then break out of the loop.

And if you want guid with just random alphanumeric ids, then use uuid package in python.