Validators

Validators are callables that raise ValidationError when a value is invalid. They can be attached to model fields or form fields.

Using validators

from buraq.forms import Form
from buraq.forms.fields import CharField, IntegerField
from buraq.validators import MinLengthValidator, MaxValueValidator, RegexValidator


class SignupForm(Form):
    username = CharField(max_length=150, validators=[MinLengthValidator(3)])
    age      = IntegerField(validators=[MaxValueValidator(120)])
    phone    = CharField(validators=[RegexValidator(r"^\+?1?\d{9,15}$")])

Built-in validators

MaxLengthValidator / MinLengthValidator

from buraq.validators import MaxLengthValidator, MinLengthValidator

MaxLengthValidator(200)   # value must be ≤ 200 characters
MinLengthValidator(3)     # value must be ≥ 3 characters

MaxValueValidator / MinValueValidator

from buraq.validators import MaxValueValidator, MinValueValidator

MaxValueValidator(100)    # numeric value must be ≤ 100
MinValueValidator(0)      # numeric value must be ≥ 0

RegexValidator

from buraq.validators import RegexValidator

phone = RegexValidator(
    regex   = r"^\+?1?\d{9,15}$",
    message = "Enter a valid phone number.",
    code    = "invalid_phone",
)

# inverse_match=True — passes only when the value does NOT match
no_spaces = RegexValidator(r"\s", inverse_match=True, message="Spaces are not allowed.")

EmailValidator

from buraq.validators import EmailValidator, validate_email

validate_email("alice@example.com")   # OK
validate_email("not-an-email")        # raises ValidationError

URLValidator

from buraq.validators import URLValidator, validate_url

validate_url("https://example.com")  # OK
validate_url("not a url")            # raises ValidationError

SlugValidator / UnicodeSlugValidator

from buraq.validators import SlugValidator, UnicodeSlugValidator

SlugValidator()         # letters, numbers, hyphens, underscores
UnicodeSlugValidator()  # same but allows unicode letters

DecimalValidator

from buraq.validators import DecimalValidator

v = DecimalValidator(max_digits=8, decimal_places=2)
v("12345.99")   # OK
v("123456.789") # raises ValidationError — too many decimal places

validate_integer

from buraq.validators import validate_integer

validate_integer("42")    # OK
validate_integer("abc")   # raises ValidationError

validate_ipv4_address / validate_ipv6_address / validate_ipv46_address

from buraq.validators import validate_ipv4_address, validate_ipv6_address, validate_ipv46_address

validate_ipv4_address("192.168.1.1")   # OK
validate_ipv6_address("::1")           # OK
validate_ipv46_address("10.0.0.1")     # OK — accepts both v4 and v6

FileExtensionValidator

from buraq.validators import FileExtensionValidator

v = FileExtensionValidator(allowed_extensions=["pdf", "docx"])
v(upload_file)   # raises ValidationError if not .pdf or .docx

validate_image_file_extension

from buraq.validators import validate_image_file_extension

# Accepts: .png, .jpg, .gif, .webp, .svg, .bmp, .tiff, .ico, .avif, .apng
validate_image_file_extension(upload_file)

StepValueValidator

from buraq.validators import StepValueValidator

v = StepValueValidator(step=5)
v(10)  # OK
v(11)  # raises ValidationError — not a multiple of 5

# With offset
v2 = StepValueValidator(step=2, offset=1)
v2(3)  # OK (3-1=2, multiple of 2)

ProhibitNullCharactersValidator

from buraq.validators import ProhibitNullCharactersValidator

v = ProhibitNullCharactersValidator()
v("hello\x00world")  # raises ValidationError

BaseValidator

Base class for limit-value validators. Subclass and override compare and clean:

from buraq.validators import BaseValidator

class EvenValueValidator(BaseValidator):
    message = "Value must be even (got %(show_value)s)."
    code    = "not_even"

    def compare(self, value, limit):
        return value % 2 != 0

    def clean(self, value):
        return int(value)

int_list_validator

from buraq.validators import int_list_validator

v = int_list_validator(sep=",", allow_negative=False)
v("1,2,3")    # OK
v("1,-2,3")   # raises ValidationError — negatives not allowed
v("1,abc,3")  # raises ValidationError — not an integer

Writing custom validators

from buraq.exceptions import ValidationError


def validate_no_profanity(value: str) -> None:
    if "badword" in value.lower():
        raise ValidationError("Profanity is not allowed.", code="profanity")

Attach to a form field:

from buraq.forms.fields import CharField

name = CharField(validators=[validate_no_profanity])

Convenience singletons

from buraq.validators import validate_email, validate_slug, validate_unicode_slug, validate_url