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wagtail/docs/advanced_topics/images/custom_image_model.rst
2016-01-27 11:27:16 +00:00

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.. _custom_image_model:
Custom image models
===================
The ``Image`` model can be customised, allowing additional fields to be added
to images.
To do this, you need to add two models to your project:
- The image model itself that inherits from
``wagtail.wagtailimages.models.AbstractImage``. This is where you would add
your additional fields
- The renditions model that inherits from
``wagtail.wagtailimages.models.AbstractRendition``. This is used to store
renditions for the new model.
Here's an example:
.. code-block:: python
# models.py
from django.db import models
from django.db.models.signals import pre_delete
from django.dispatch import receiver
from wagtail.wagtailimages.models import Image, AbstractImage, AbstractRendition
class CustomImage(AbstractImage):
# Add any extra fields to image here
# eg. To add a caption field:
# caption = models.CharField(max_length=255)
admin_form_fields = Image.admin_form_fields + (
# Then add the field names here to make them appear in the form:
# 'caption',
)
class CustomRendition(AbstractRendition):
image = models.ForeignKey(CustomImage, related_name='renditions')
class Meta:
unique_together = (
('image', 'filter', 'focal_point_key'),
)
# Delete the source image file when an image is deleted
@receiver(pre_delete, sender=CustomImage)
def image_delete(sender, instance, **kwargs):
instance.file.delete(False)
# Delete the rendition image file when a rendition is deleted
@receiver(pre_delete, sender=CustomRendition)
def rendition_delete(sender, instance, **kwargs):
instance.file.delete(False)
.. note::
If you are using image feature detection, follow these instructions to
enable it on your custom image model: :ref:`feature_detection_custom_image_model`
Then set the ``WAGTAILIMAGES_IMAGE_MODEL`` setting to point to it:
.. code-block:: python
WAGTAILIMAGES_IMAGE_MODEL = 'images.CustomImage'
.. topic:: Migrating from the builtin image model
When changing an existing site to use a custom image model. No images will
be copied to the new model automatically. Copying old images to the new
model would need to be done manually with a
`data migration <https://docs.djangoproject.com/en/1.8/topics/migrations/#data-migrations>`_.
Any templates that reference the builtin image model will still continue to
work as before but would need to be updated in order to see any new images.