customimage.py

from django.db import models
from wagtail.images.models import Image, AbstractImage, AbstractRendition


class CustomImage(AbstractImage):
    slug = models.CharField(
        max_length=1000,
        blank=True,
        null=True,
        help_text="Free-form text. Can be used to store the image filename or other workflow-related information.",
    )
    attribution = models.CharField(
        max_length=255,
        blank=True,
        null=True,
        help_text="Organization/Photographer. Image description can be set via the caption.",
    )

    admin_form_fields = Image.admin_form_fields + (
        "attribution",
        "slug",
    )


class CustomRendition(AbstractRendition):
    """This class is required by Wagtail when using a custom image."""

    image = models.ForeignKey(
        CustomImage, on_delete=models.CASCADE, related_name="renditions"
    )

    class Meta:
        unique_together = (("image", "filter_spec", "focal_point_key"),)