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blog.pyaqa.ru/app/domain/value_objects/slug.py
Sergey Vanyushkin ca4e8877a5 docs: add AI code generation requirements and comprehensive Google-style docstrings
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2026-05-02 13:15:21 +03:00

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Python

"""Slug value object for URL-friendly identifiers.
This module defines the Slug value object for generating and validating
URL-friendly slugs from titles. Enforces lowercase, alphanumeric, and
hyphen-only format.
"""
import re
from dataclasses import dataclass
from app.domain.value_objects.base import ValueObject
@dataclass(frozen=True, slots=True)
class Slug(ValueObject[str]):
"""URL slug value object.
Represents a URL-friendly identifier generated from titles.
Validates format and provides factory method for slug generation.
Attributes:
value: The slug string value.
MAX_LENGTH: Maximum allowed slug length (200 characters).
SLUG_PATTERN: Regex pattern for valid slug format.
Raises:
ValueError: If slug format is invalid.
Example:
>>> slug = Slug.from_title("My First Post!")
>>> print(slug.value)
'my-first-post'
"""
MAX_LENGTH: int = 200
SLUG_PATTERN: str = r"^[a-z0-9]+(?:-[a-z0-9]+)*$"
def _validate(self) -> None:
"""Validate slug format.
Ensures slug contains only lowercase letters, numbers, and hyphens.
Raises:
ValueError: If slug format is invalid.
"""
if not isinstance(self.value, str):
raise ValueError("Slug must be a string")
if len(self.value) > self.MAX_LENGTH:
raise ValueError(f"Slug must be at most {self.MAX_LENGTH} characters")
if not re.match(self.SLUG_PATTERN, self.value):
raise ValueError("Slug must contain only lowercase letters, numbers, and hyphens")
@classmethod
def from_title(cls, title: str) -> "Slug":
"""Generate slug from title.
Converts title to URL-friendly format by lowercasing, removing
special characters, and replacing spaces with hyphens.
Args:
title: Source title string.
Returns:
New Slug instance with generated value.
"""
slug = title.lower().strip()
slug = re.sub(r"[^a-z0-9\s-]", "", slug)
slug = re.sub(r"[-\s]+", "-", slug)
max_len = 200
slug = slug[:max_len].strip("-")
if not slug:
slug = "post"
return cls(value=slug)