Do not block on opening catalogs

bluesky_widgets/components/search/searches.py

@@ -127,9 +127,9 @@ def enter(self, name):
             old = self._root_catalog
         new = old[name]
 
-        # Touch an attribute that will trigger a connection attempt. (It's here
+        # Access an entry to trigger a connection attempt. (It's here
         # that an error would be raised if, say, a database is unreachable.)
-        new.metadata
+        next(new.items())
 
         # If we get this far, it worked.
         self._subcatalogs.append(new)

bluesky_widgets/qt/searches.py

@@ -12,6 +12,7 @@
 )
 from .search_input import QtSearchInput
 from .search_results import QtSearchResults
+from .threading import create_worker
 
 logger = logging.getLogger(__name__)
 
@@ -46,9 +47,7 @@ def __init__(self, model, *args, **kwargs):
         self._back_button.clicked.connect(model.go_back)
 
         # Hook up model Events to Qt Slots.
-        self.model.events.enter.connect(self.on_enter)
         self.model.events.go_back.connect(self.on_go_back)
-        self.model.events.run_search_ready.connect(self.on_run_search_ready)
         self.model.events.run_search_cleared.connect(self.on_run_search_cleared)
 
         self._selector_widgets = []  # QComboBoxes
@@ -68,26 +67,40 @@ def __init__(self, model, *args, **kwargs):
             # box.
             self._initialize_selector(list(model.current_catalog))
 
-    def on_enter(self, event=None):
-        "We are entering a subcatalog."
-        names = list(event.catalog)
-        self._initialize_selector(names)
-        self._back_button.setEnabled(True)
-
     def _initialize_selector(self, names):
         "Create a combobox to select from subcatalogs."
         selector = QtSubcatalogSelector(names)
         self._selector_widgets.append(selector)
 
         def on_selection(index):
             name = names[index]
-            try:
-                self.model.enter(name)
-            except Exception:
-                logger.exception("Failed to select %r", name)
+            selector.setEnabled(False)
+
+            def on_errored(err):
+                logger.exception("Failed to select %r", name, exc_info=err)
+                # Reset the combobox selection to an empty value and enable it.
                 selector.setCurrentIndex(-1)
-            else:
-                selector.setEnabled(False)
+                selector.setEnabled(True)
+
+            def on_success(return_value):
+                # return_value is None
+                if self.model.run_search is None:
+                    # We have a Catalog of Catalogs.
+                    names = list(self.model.current_catalog)
+                    self._initialize_selector(names)
+                else:
+                    # We have a Catalog of Runs.
+                    self._initialize_run_search(
+                        self.model.run_search.search_input,
+                        self.model.run_search.search_results
+                    )
+                self._back_button.setEnabled(True)
+
+            create_worker(
+                self.model.enter,
+                name,
+                _connect={"errored": on_errored, "returned": on_success}
+            )
 
         selector.activated.connect(on_selection)
         self.layout().addWidget(selector)
@@ -106,11 +119,6 @@ def on_go_back(self, event):
             # This is the last widget. Disable back button.
             self._back_button.setEnabled(False)
 
-    def on_run_search_ready(self, event):
-        "We have a catalog of Runs."
-        self._initialize_run_search(event.search_input, event.search_results)
-        self._back_button.setEnabled(True)
-
     def _initialize_run_search(self, search_input, search_results):
         "Create search input and output for a catalog of Runs."
         # Create run search widgets and stash them as state for removal later.