Fields

The following fields (and concepts) are offered by undermythumb.

Available fields

undermythumb comes with two fields, each with specific use cases.

ImageWithThumbnailsField

The name says it all – this field is used to accept an image and cut thumbnails. Thumbnails are stored using whatever storage is available to the field.

Defining thumbnails

Thumbnails are defined as a tuple of tuples passed as thumbnails to the field.

Each tuple is defined as (thumbnail key, renderer instance). The thumbnail key becomes the thumbnail’s key when using the field’s thumbnails attribute to display a thumbnail, and part of the filename generated on creation.

Example:

artwork = ImageWithThumbnailsField(
    thumbnails = (('related_content', CropRenderer(150, 150)), ),
    upload_to='artwork/',
)

In the example above, artwork has one thumbnail: related_content.

In a template (or Python code), you can access related_content via thumbnails:

{# assuming 'object' is an instance of your model #}
{{ object.artwork.thumbnails.related_content.url }}

Note

For a complete list of renderers, see: List of available renderers.

ImageFallbackField

This field is only a subclass of Django’s ImageField with the ability to use images or thumbnails from another field.

This field came out of the need to offer a way to optionally override another field’s thumbnail. To fall back to another field or thumbnail’s value, simply define a dotted path to another model attribute. Using the example, above:

related_content_image = ImageFallbackField(
    fallback_path='artwork.thumbnails.related_content',
    upload_to='artwork/'
)

Since this is at its core an ImageField, using in a template is as simple as:

{# assuming 'object' is an instance of your model #}
{{ object.related_content_image.url }}

But, here’s what makes it special – as defined, this field will do one of two things when accessed:

1. If the field has a value (a file has been uploaded), it will return that value.
2. If the field is empty, it will return the thumbnail from its fallback path, artwork.thumbnails.related_content.