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Eyened Platform

ORM utilities

Thumbnail management

The ORM uses the ThumbnailPath column of ImageInstance to store thumbnail path and state:

  • NULL means that the image contains no thumbnail and the thumbnail generation code must be ran on this image.
  • An empty string indicates that the thumbnail generator ran and failed for this image.
  • Any other value will be interpreted as a relative path to the image thumbnail within the THUMBNAILS_PATH directory. In practice, the thumbnail generator will generate multiple thumbnail sizes and a suffix must be appended to correctly locate a thumbnail file. For example, the thumbnail of 144px (side) will be stored at <THUMBNAILS_PATH>/<image.ThumbnailPath>_144.jpg.

This section explains how to update thumbnails in the database, potentially after the thumbnail generation code has been updated.

Generating thumbnails

The ORM contains a simple update_thumbnails script that will update thumbnails in the database:

eorm update-thumbnails --env prod

This example uses an environment called prod to determine what database to connect to and where to write thumbnails. This environment must be provided in a .env file as explained in ORM Configuration.

By default, eorm update-thumbnails will run for images with ThumbnailPath == NULL. To run also on images with failed thumbnails (useful after the thumbnail generation code has been updated) use:

eorm update-thumbnails --failed --env prod

Updating thumbnail generation code

To updated the thumbnail generation code to support new image types or generally change the way thumbnails are generated:

  1. Update the thumbnail generation code. The ORM includes a notebook to easily visualize the output of these methods on a sample images from the database.

  2. For any images that need to be updated in the database, set ThumbnailPath to NULL.

  3. Run the thumbnail update script:

    eorm update-thumbnails --failed --env prod