Layer post_save deletes links to external thumbnails / data

[srtonz]

Expected Behavior

When saving a layer, existing links should only be updated / deleted if required.

Actual Behavior

When saving a layer, links to external data such as thumbnails stored on a static file host are deleted.

Steps to Reproduce the Problem

1. Set a layer's thumbnail link to an external image through the admin panel
2. Save the layer through the admin panel
3. Thumbnail is deleted

Specifications

• GeoNode version: 2.10
• Installation method (manual, GeoNode Docker, SPCGeoNode Docker): manual docker
• Platform: ubuntu
• Additional details:

Reasons

After saving a layer, the resourcebase_post_save signal is triggered. It deletes any links that do not point to the same host as our GeoNode instance:

geonode/geonode/base/models.py

Lines 1412 to 1424 in c999687

	def resourcebase_post_save(instance, *args, **kwargs):
	"""
	Used to fill any additional fields after the save.
	Has to be called by the children
	"""
	# we need to remove stale links
	for link in instance.link_set.all():
	if link.name == "External Document":
	if link.resource.doc_url != link.url:
	link.delete()
	else:
	if urlsplit(settings.SITEURL).hostname not in link.url:
	link.delete()

I'm not entirely sure why this behaviour exists, so I'm hesitant to submit a pull request. I think having external resources is a very valid scenario, but there may be a reason for deleting links to external hosts?

[afabiani]

@geotob we need to try to understand which was the original intent of this code. At first glance, I agree with you. It doesn't seem to make much sense to delete the old links.
Maybe this was introduced to keep the server IP/name consistent?