Apply suggestions from code review

Co-authored-by: Norman Fomferra <[email protected]>

Author: b-yogesh

CHANGES.md

@@ -17,8 +17,11 @@
   - Updated schema for the `num_levels` parameter which now explains the parameter 
     in more detail.
 
-* Improved Extension Demo Panels.
-  See https://github.com/xcube-dev/xcube/issues/1134
+* Improved the demos for the xcube Viewer server-side extensions in various ways (#1134):
+  - enhanced user input validation
+  - added error message label
+  - fixed bugs in code
+  - improved UI styles and general UX
 
 ## Changes in 1.9.0
 

examples/serve/panels-demo/demo_panels/panel_histo2d.py

@@ -63,7 +63,7 @@ def render_panel(
     )
 
     if time_label:
-        text = f"{dataset_title} " f"/ {time_label[0:-1]}"
+        text = f"{dataset_title} / {time_label[0:-1]}"
     else:
         text = f"{dataset_title}"
     place_text = Typography(id="text", children=[text], align="center")
@@ -102,7 +102,7 @@ def render_panel(
     )
 
     error_message = Typography(
-        id="error_message", style={"color": "red"}, children=["Error: Panel Disabled"]
+        id="error_message", style={"color": "red"}, children=["Missing variable selection"]
     )
 
     return Box(
@@ -191,12 +191,12 @@ def update_plot(
     ):
         return (
             None,
-            "Error: 2-D histogram only works for geometries with a non-zero extent.",
+            "Selected geometry must cover and area.",
         )
 
     dataset = mask_dataset_by_geometry(dataset, place_geometry)
     if dataset is None:
-        return None, "Error: dataset is None after masking, invalid geometry?"
+        return None, "Selected geometry produces empty subset"
 
     var_1_data: np.ndarray = dataset[var_1_name].values.ravel()
     var_2_data: np.ndarray = dataset[var_2_name].values.ravel()

examples/serve/panels-demo/demo_panels/panel_spectrum.py

@@ -45,7 +45,7 @@ def render_panel(
         theme=theme_mode,
     )
     if time_label:
-        text = f"{dataset_id} " f"/ {time_label[0:-1]}"
+        text = f"{dataset_id} / {time_label[0:-1]}"
     else:
         text = f"{dataset_id}"
     place_text = Typography(id="text", children=[text], align="center")
@@ -129,7 +129,7 @@ def update_error_message(
     return ""
 
 
-def get_wavelength(
+def get_spectra(
     dataset: xr.Dataset,
     place_group: gpd.GeoDataFrame,
     places: list,

xcube/webapi/viewer/contrib/helpers.py

@@ -17,7 +17,7 @@ def get_dataset(ctx: Context, dataset_id: str | None = None) -> xr.Dataset | Non
     return get_datasets_ctx(ctx).get_dataset(dataset_id) if dataset_id else None
 
 
-def get_place_name(place_id: str, place_group: list[dict[str, Any]]) -> str | None:
+def get_place_label(place_id: str, place_group: list[dict[str, Any]]) -> str | None:
     if not place_group or not place_id:
         return None
     for place in place_group: