Python // User validation

uservalidation

Published // 2026-05-28 Category // Python basics Status // learning log

A small Python exercise focused on validating user input before registration. The function checks a name, an email address and a password by delegating each validation rule to smaller helper functions.

What this function does

The goal is deliberately simple: keep the registration flow clean by separating validation from user creation. First, validate_user() checks the three input fields. Then, register_user() returns a user dictionary only if every validation step succeeds.

Name: must pass validate_name(name).
Email: must pass validate_email(email).
Password: must pass validate_password(password).
Failure behavior: validation errors are converted into False during registration.

small_user_validation_function.py

from python_functions import validate_name, validate_email, validate_password

def validate_user(name, email, password):
    """Validate the user name, email and password.

    Args:
        name (string): Name that we're attempting to validate.
        email (string): Email address that we're attempting to validate.
        password (string): Password that we're attempting to validate.

    Returns:
        bool: Returns True if all validation checks pass.

    Raises:
        ValueError: If any validation check fails.
    """
    if validate_name(name) == False:
        raise ValueError("Please make sure your name is greater than 2 characters!")

    if validate_email(email) == False:
        raise ValueError("Your email address is in the incorrect format, please enter a valid email.")

    if validate_password(password) == False:
        raise ValueError("Your password is too weak, ensure that your password is greater than 8 characters, "
                         "contains a capital letter and a number.")

    return True

def register_user(name, email, password):
    """Attempt to register the user if they pass validation.

    Args:
        name (string): Name of the user.
        email (string): Email address of the user.
        password (string): Password of the user.

    Returns:
        dict or bool: Returns a dictionary with the user details if validation is successful,
        or False if the validation fails.
    """
    try:
        validate_user(name, email, password)
    except:
        return False

    user = {
        "name": name,
        "email": email,
        "password": password
    }

    return user

Development notes

This is a useful first pattern because it introduces a common backend idea: validation should happen before persistence or account creation. In a larger application, the same structure could be extended with typed exceptions, password hashing and database storage.

One future improvement would be replacing the broad except: block with except ValueError:, so unexpected errors are not silently swallowed.

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