.. _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.images.models.AbstractImage``. This is where you would add
   your additional fields
 - The renditions model that inherits from
   ``wagtail.images.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 wagtail.images.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, blank=True)

        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, on_delete=models.CASCADE, related_name='renditions')

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


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
    :ref:`data migration <django: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.

.. _custom_image_model_referring_to_image_model:

Referring to the image model
============================

.. module:: wagtail.images

.. autofunction:: get_image_model

.. autofunction:: get_image_model_string
