Nested helpers don't overwrite helper reference (#1546)

* Don't overwrite helper reference

* Add Changelog

* Update Changelog

* Update CHANGES.rst

Co-authored-by: P. L. Lim <[email protected]>

* Add nested_helper cubeviz test

* Remove unneeded import

Co-authored-by: P. L. Lim <[email protected]>

Author: duytnguyendtn

CHANGES.rst

@@ -52,6 +52,9 @@ Cubeviz
 
 - Fixed validation message of moment number in moment map plugin. [#1536]
 
+- Fixed ``viewer.jdaviz_helper`` returning Specviz helper instead of Cubeviz helper after Specviz
+  helper is called via ``Cubeviz.specviz``. Now ``viewer.jdaviz_helper`` always returns the Cubeviz helper. [#1546]
+
 Imviz
 ^^^^^
 

jdaviz/configs/cubeviz/plugins/tests/test_cubeviz_helper.py

@@ -0,0 +1,10 @@
+def test_nested_helper(cubeviz_helper):
+    '''Ensures the Cubeviz helper is always returned, even after the Specviz helper is called'''
+    # Force Specviz helper to instantiate
+    cubeviz_helper.specviz
+
+    assert cubeviz_helper.app._jdaviz_helper == cubeviz_helper
+
+    # The viewers also have a callthrough to the app's _jdaviz_helper attribute
+    spec_viewer = cubeviz_helper.app.get_viewer('spectrum-viewer')
+    assert spec_viewer.jdaviz_helper == cubeviz_helper

jdaviz/core/helpers.py

@@ -53,7 +53,9 @@ def __init__(self, app=None, verbosity='warning', history_verbosity='info'):
 
         # give a reference from the app back to this config helper.  These can be accessed from a
         # viewer via viewer.jdaviz_app and viewer.jdaviz_helper
-        self.app._jdaviz_helper = self
+        # if the helper has already been set, this is probably a nested viz tool. Don't overwrite
+        if not hasattr(self.app, '_jdaviz_helper'):
+            self.app._jdaviz_helper = self
 
         self.app.hub.subscribe(self, SubsetCreateMessage,
                                handler=lambda msg: self._propagate_callback_to_viewers('_on_subset_create', msg)) # noqa