Use placeholder for dropdowns

app.py

@@ -39,15 +39,6 @@ def none_if_empty(val):
     return None if val == "" else val
 
 
-def compute_dept_dropdown_options(reg_code=None):
-    """Compute department dropdown option list."""
-    dep_list = [
-        {"label": dep[1], "value": dep[0]}
-        for dep in app_data.compute_dep_list(reg_code)
-    ]
-    return [{"label": "-- département --", "value": ""}] + dep_list
-
-
 external_stylesheets = ["https://unpkg.com/tailwindcss@^1.0/dist/tailwind.min.css"]
 
 server = flask.Flask(__name__)
@@ -68,12 +59,10 @@ app.layout = html.Div(
                     children=[
                         dcc.Dropdown(
                             id="region",
+                            placeholder="Région...",
                             options=[
-                                {"label": "-- région --", "value": ""},
-                                *[
-                                    {"label": reg[1], "value": reg[0]}
-                                    for reg in app_data.reg_list
-                                ],
+                                {"label": label, "value": value}
+                                for value, label in app_data.reg_list
                             ],
                             value="",
                         ),
@@ -83,24 +72,17 @@ app.layout = html.Div(
                     className="mb-2",
                     children=[
                         dcc.Dropdown(
-                            id="departement",
-                            options=compute_dept_dropdown_options(),
-                            value="",
+                            id="departement", placeholder="Département...", value=""
                         ),
                     ],
                 ),
             ],
         ),
-        dcc.Loading(
-            id="loading-charts",
+        html.Div(
+            className="flex",
             children=[
-                html.Div(
-                    className="flex",
-                    children=[
-                        dcc.Graph(id="bar-chart", className="w-1/2"),
-                        dcc.Graph(id="map", className="w-1/2"),
-                    ],
-                )
+                dcc.Graph(id="bar-chart", className="w-1/2"),
+                dcc.Graph(id="map", className="w-1/2"),
             ],
         ),
     ],
@@ -116,7 +98,11 @@ app.layout = html.Div(
 )
 def update_dept_dropdown_options(reg_code):
     """Update department list when a region has been chosen."""
-    options = compute_dept_dropdown_options(reg_code=none_if_empty(reg_code))
+    reg_code = none_if_empty(reg_code)
+    options = [
+        {"label": label, "value": value}
+        for value, label in app_data.compute_dep_list(reg_code)
+    ]
     value = ""
     return options, value