smarter default behavior when deleting selected entry

jdaviz/configs/imviz/plugins/aper_phot_simple/aper_phot_simple.py

@@ -140,7 +140,7 @@ def _get_region_from_subset(self, subset):
     @observe('subset_selected')
     def _subset_selected_changed(self, event={}):
         subset_selected = event.get('new', self.subset_selected)
-        if self._selected_data is None:
+        if self._selected_data is None or subset_selected == '':
             self.reset_results()
             return
 

jdaviz/configs/imviz/tests/test_simple_aper_phot.py

@@ -24,7 +24,8 @@ def test_plugin_wcs_dithered(self):
         with pytest.raises(ValueError):
             # will raise an error and revert to first entry
             phot_plugin.subset_selected = 'no_such_subset'
-        assert phot_plugin.subset_selected == phot_plugin.subset.labels[0]
+        assert phot_plugin.subset_selected == ''
+        phot_plugin.subset_selected = phot_plugin.subset.labels[0]
         assert_allclose(phot_plugin.background_value, 0)
         phot_plugin.vue_do_aper_phot()
         assert not phot_plugin.result_available
@@ -35,9 +36,7 @@ def test_plugin_wcs_dithered(self):
         assert phot_plugin.current_plot_type == 'Radial Profile'  # Software default
 
         phot_plugin.data_selected = 'has_wcs_1[SCI,1]'
-        with pytest.raises(ValueError):
-            phot_plugin.subset_selected = 'no_such_subset'
-        assert phot_plugin.subset_selected == phot_plugin.subset.labels[0]
+        phot_plugin.subset_selected = phot_plugin.subset.labels[0]
         with pytest.raises(ValueError):
             phot_plugin.bg_subset_selected = 'no_such_subset'
         assert phot_plugin.bg_subset_selected == 'Manual'

jdaviz/core/template_mixin.py

@@ -234,6 +234,13 @@ def _subset_type(subset):
         else:
             return 'spectral'
 
+    def _apply_default_selection(self):
+        # default to the default_text, if available, otherwise empty
+        if self._default_text:
+            self.selected = self._default_text
+        else:
+            self.selected = ''
+
     def _subset_to_dict(self, subset):
         # find layer artist in default spectrum-viewer
         for viewer in self.viewers:
@@ -248,8 +255,8 @@ def _delete_subset(self, subset):
         # NOTE: calling .remove will not trigger traitlet update
         self.items = [s for s in self.items
                       if s['label'] != subset.label]
-        if self.selected not in self.labels and len(self.labels):
-            self.selected = self.labels[0]
+        if self.selected not in self.labels:
+            self._apply_default_selection()
 
     def _update_subset(self, subset, attribute=None):
         if self._allowed_type is not None and self._subset_type(subset) != self._allowed_type:
@@ -278,9 +285,8 @@ def _update_subset(self, subset, attribute=None):
             self._update_has_subregions()
 
     def _selected_changed(self, event):
-        if event['new'] not in self.labels:
-            if len(self.labels):
-                self.selected = self.labels[0]
+        if event['new'] not in self.labels + ['']:
+            self._apply_default_selection()
             raise ValueError(f"{event['new']} not one of {self.labels}")
         self._clear_cache("selected_obj", "selected_item")
         self._update_has_subregions()