Exclude subsets from WCS-only layer filter

[bmorris3]

Description

If you create a subset in Imviz while WCS-linked, the subset appears in the Orientation plugin's "orientation in viewer" dropdown. It does not appear in the data dropdown. This is an artifact of the way that WCS-only layers are filtered in LayerSelect. I've tweaked the filter to be sure to exclude subsets.

Change log entry

• Is a change log needed? If yes, is it added to CHANGES.rst? If you want to avoid merge conflicts,
  list the proposed change log here for review and add to CHANGES.rst before merge. If no, maintainer
  should add a no-changelog-entry-needed label.

Checklist for package maintainer(s)

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• Are two approvals required? Branch protection rule does not check for the second approval. If a second approval is not necessary, please apply the trivial label.
• Do the proposed changes actually accomplish desired goals? Also manually run the affected example notebooks, if necessary.
• Do the proposed changes follow the STScI Style Guides?
• Are tests added/updated as required? If so, do they follow the STScI Style Guides?
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• Is a milestone set? Set this to bugfix milestone if this is a bug fix and needs to be released ASAP; otherwise, set this to the next major release milestone. Bugfix milestone also needs an accompanying backport label.
• After merge, any internal documentations need updating (e.g., JIRA, Innerspace)? 🐱

[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 88.74%. Comparing base (23b3edd) to head (b13c3bc).

Files	Patch %	Lines
jdaviz/utils.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3097      +/-   ##
==========================================
+ Coverage   88.73%   88.74%   +0.01%     
==========================================
  Files         111      111              
  Lines       17262    17257       -5     
==========================================
- Hits        15317    15315       -2     
+ Misses       1945     1942       -3     

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[kecnry]

wait, so subset.state.meta['_WCS_ONLY'] is sometimes set and True? 🤔

[bmorris3]

I tried to simplify this whole function, but there were corner cases that got messy. The layers that get passed through LayerSelect can have the following attributes: data, layer, or meta:

jdaviz/jdaviz/utils.py

Lines 244 to 252 in 23b3edd

	# exclude WCS-only layers from the layer choices:
	if hasattr(layer, 'layer'):
	state = layer.layer
	elif hasattr(layer, 'data'):
	state = layer.data
	elif hasattr(layer, 'meta'):
	state = layer
	else:
	raise NotImplementedError

In the case where the layer is a subset, layer.data corresponds to the subset's parent Data, which itself may have a meta['_WCS_ONLY']. That's where the second check is necessary.

[bmorris3]

I'm experimenting right now to see if this works without the second elif. 🤞🏻

[bmorris3]

Phew, much simplified in b13c3bc.

[bmorris3]

Sorry, I merged this before two approvals without first labeling as trivial. If anyone disagrees, I can revert or follow up with another PR.