AutoSlugField.py

AutoSlugField.py

from typing import Callable
from django.core import checks
from django.db import models
from django.utils.functional import cached_property
from django.utils.text import slugify
from django.utils.translation import gettext_lazy as _


class AutoSlugField(models.SlugField):
    """
    Generates a slug by slugifying the value of a
    sibling field on the same model class.
    """
    description = _("Auto Slug Field")

    def __init__(self, *args, field: str,
                 slugify: Callable = slugify, **kwargs):
        self.field = field
        self.slugify = slugify
        super().__init__(*args, **kwargs)

    def check(self, **kwargs):
        return [
            *super().check(**kwargs),
            *self._check_slugify_is_callable(**kwargs),
        ]

    def _check_slugify_is_callable(self, **kwargs):
        if not callable(self.slugify):
            return [
                checks.Error(
                    "'slugify' must be callable.",
                    obj=self,
                    id='fields.E001',
                )
            ]
        return []

    def pre_save(self, model_instance, add):
        if not getattr(model_instance, self.attname):
            value = getattr(model_instance, self.field)
            slug = self.slugify(value)
            setattr(model_instance, self.attname, slug)
            return slug
        return super().pre_save(model_instance, add)

    def deconstruct(self):
        name, path, args, kwargs = super().deconstruct()

        if self.field is not None:
            kwargs['field'] = self.field

        if self.slugify is not None:
            kwargs['slugify'] = self.slugify

        return name, path, args, kwargs