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Accepted
NoahVerner
Asked: 2022-10-20 14:27:19 +0800 CST 2022-10-20 14:27:19 +0800 CST

How to tell if a custom random string function returns a string that matches a particular regular expression in Python 3?

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Context:

One of the great features that the market has API de Binanceis that it allows its users to set a custom order id ( also known as newClientOrderId ) for each trade they make on the market Binance Futures, this feature becomes useful if someone wants to keep track of the trades being made. made following a particular trading strategy.

According to your Documentos oficiales, the parameter that will be sent in the POST request to put the new command must be newClientOrderIdand its value must match this regular expression criteria:^[\.A-Z\: /a-z0-9_-]{1,36}$

Problem:

I wrote a simple random string function in Python that returns a random string based on 2 parameters which are a string and the length of the desired string to match, here it is:

import random, string
def randstr(s, length):

    all_chars = string.ascii_lowercase
    result = s
    for i in range(length):
        result += random.choice(all_chars)
    return(result)

Tests

randstr('test1',5)
Out[14]: 'test1uljgp'

randstr('test1',2)
Out[15]: 'test1mo'

randstr('test1',5)
Out[16]: 'test1pbgjw'

So how do I know if the output of my randstrcustom function matches this regex criteria: ^[\.A-Z\:/a-z0-9_-]{1,36}$? Knowing this, I will make sure that future developments related to this API continue to work non-stop.

python-3.x

1 Answers

  1. Best Answer

    You can always apply the method search()to check if a particular string satisfies a regular expression. This is applied after calling the functionrandstr()

    import re

patron = re.compile(r"^[\.A-Z\: /a-z0-9_-]{1,36}$")

if patron.search(orderId):
    print(f"Order {orderId} cumple")
else:
    print(f"Order {orderId} no cumple")

    Since the pattern already includes the match of the start and end of text, we use a search()instead of match().

    show

    import random, string, re

patron = re.compile(r"^[\.A-Z\: /a-z0-9_-]{1,36}$")

def randstr(s, length):

    all_chars = string.ascii_lowercase
    result = s
    for i in range(length):
        result += random.choice(all_chars)
    return(result)

tests = [
    "AA",
    "A_A",
    "123A",
    "Aa",
    "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
]

for test in tests:
    orderId = randstr(test, 8)
    if patron.search(orderId):
        print(f"Order {orderId} cumple")
    else:
        print(f"Order {orderId} no cumple")

    produces:

    Order AAqiukdgcu cumple
Order A_Adymvkwty cumple
Order 123Avalwtpox cumple
Order Aaljnsyiil cumple
Order AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAinyaekji no cumple

Process finished with exit code 0
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