Bug fix for toga.Selection on android for value

changes/1723.bugfix.rst

@@ -0,0 +1 @@
+A Selection widget with no items now consistently returns a current value of ``None`` on all platforms.

cocoa/src/toga_cocoa/widgets/selection.py

@@ -43,7 +43,9 @@ def select_item(self, item):
         self.native.selectItemWithTitle(item)
 
     def get_selected_item(self):
-        return str(self.native.titleOfSelectedItem)
+        selected = self.native.titleOfSelectedItem
+        if selected:
+            return str(selected)
 
     def set_on_select(self, handler):
         pass

examples/selection/selection/app.py

@@ -19,6 +19,9 @@ def startup(self):
 
         # Add the content on the main window
         self.selection = toga.Selection(items=self.OPTIONS)
+        self.empty_selection = toga.Selection()
+
+        self.report_label = toga.Label("", style=label_style)
 
         self.main_window.content = toga.Box(
             children=[
@@ -29,6 +32,22 @@ def startup(self):
                         self.selection,
                     ],
                 ),
+                toga.Box(
+                    style=box_style,
+                    children=[
+                        toga.Label("Empty selection", style=label_style),
+                        self.empty_selection,
+                    ],
+                ),
+                toga.Box(
+                    style=box_style,
+                    children=[
+                        toga.Button(
+                            "Report on selection", on_press=self.report_selection
+                        ),
+                        self.report_label,
+                    ],
+                ),
                 toga.Box(
                     style=box_style,
                     children=[
@@ -66,7 +85,7 @@ def startup(self):
                 toga.Box(
                     style=box_style,
                     children=[
-                        toga.Label("use some style!", style=label_style),
+                        toga.Label("Use some style!", style=label_style),
                         toga.Selection(
                             style=Pack(width=200, padding=24),
                             items=["Curium", "Titanium", "Copernicium"],
@@ -113,6 +132,11 @@ def my_on_select(self, selection):
 
         print(f"The selection widget changed to {selection.value}")
 
+    def report_selection(self, widget):
+        self.report_label.text = (
+            f"Element: {self.selection.value!r}; Empty: {self.empty_selection.value!r}"
+        )
+
 
 def main():
     # App name and namespace

iOS/src/toga_iOS/widgets/selection.py

@@ -69,7 +69,10 @@ def select_item(self, item):
         self.interface.factory.not_implemented("Selection.select_item()")
 
     def get_selected_item(self):
-        return self.interface.items[self.picker.selectedRowInComponent(0)]
+        try:
+            return self.interface.items[self.picker.selectedRowInComponent(0)]
+        except IndexError:
+            return None
 
     def set_on_select(self, handler):
         # No special handling required