Add SnackBar action examples and improve action handling (#5813)

Introduces a new Python example demonstrating SnackBar actions, updates documentation with new examples and images, and enhances integration tests for SnackBar actions. The Dart SnackBar control is updated to better distinguish between string and control-based actions. Minor doc corrections and test refactoring are also included.

Author: FeodorFitsner

packages/flet/lib/src/controls/snack_bar.dart

@@ -46,9 +46,9 @@ class _SnackBarControlState extends State<SnackBarControl> {
           "SnackBar.content must be provided and visible");
     }
 
-    final actionControl = widget.control.child("action");
+    final actionControl = widget.control.get("action");
     SnackBarAction? action;
-    if (actionControl != null) {
+    if (actionControl is Control) {
       action = SnackBarAction(
         label: actionControl.getString("label", "Action")!,
         backgroundColor: actionControl.getColor("bgcolor", context),
@@ -59,14 +59,11 @@ class _SnackBarControlState extends State<SnackBarControl> {
             actionControl.getColor("disabled_text_color", context),
         onPressed: () => actionControl.triggerEvent("click"),
       );
-    } else {
-      var label = widget.control.getString("action");
-      action = label != null
-          ? SnackBarAction(
-              label: label,
-              onPressed: () {},
-            )
-          : null;
+    } else if (actionControl is String) {
+      action = SnackBarAction(
+        label: actionControl,
+        onPressed: () => widget.control.triggerEvent("action"),
+      );
     }
 
     var width = widget.control.getDouble("width");

sdk/python/examples/controls/snack_bar/action.py

@@ -0,0 +1,34 @@
+import flet as ft
+
+
+def main(page: ft.Page):
+    def open_simple_action(e: ft.Event[ft.Button]):
+        page.show_dialog(
+            ft.SnackBar(
+                ft.Text("The file has been deleted."),
+                action="Undo",
+                on_action=lambda e: print("Simple Undo clicked"),
+            )
+        )
+
+    def open_custom_action(e: ft.Event[ft.Button]):
+        page.show_dialog(
+            ft.SnackBar(
+                ft.Text("The directory has been deleted."),
+                action=ft.SnackBarAction(
+                    label="Undo delete",
+                    text_color=ft.Colors.YELLOW,
+                    bgcolor=ft.Colors.BLUE,
+                    on_click=lambda e: print("Custom Undo clicked"),
+                ),
+            )
+        )
+
+    page.add(
+        ft.Button("Open SnackBar with a Simple action", on_click=open_simple_action),
+        ft.Button("Open SnackBar with a Custom action", on_click=open_custom_action),
+    )
+
+
+if __name__ == "__main__":
+    ft.run(main)

sdk/python/packages/flet/docs/controls/snackbar.md

@@ -28,6 +28,15 @@ snack_bar_action_class_name: flet.SnackBarAction
 
 {{ image(example_images + "/snack_bar_flow.gif", alt="Snack bar with counter", caption="Snack bar with counter",width="50%") }}
 
+### Action
+
+```python
+--8<-- "{{ examples }}/action.py"
+```
+
+{{ image(example_images + "/action_simple.png", alt="Snack bar with a simple action", caption="Snack bar with a simple action", width="50%") }}
+
+{{ image(example_images + "/action_custom.png", alt="Snack bar with a custom action", caption="Snack bar with a custom action", width="50%") }}
 
 {{ class_members(class_name) }}
 

sdk/python/packages/flet/integration_tests/controls/material/golden/macos/snack_bar/basic.png

@@ -5,15 +5,56 @@
 
 
 @pytest.mark.asyncio(loop_scope="module")
-async def test_snack_bar_basic(flet_app: ftt.FletTestApp, request):
+async def test_basic(flet_app: ftt.FletTestApp, request):
     flet_app.page.enable_screenshots = True
-    flet_app.resize_page(400, 600)
+    flet_app.resize_page(500, 300)
     flet_app.page.show_dialog(ft.SnackBar(ft.Text("Hello, world!")))
     flet_app.page.update()
     await flet_app.tester.pump_and_settle()
 
     flet_app.assert_screenshot(
-        "snack_bar_basic",
+        request.node.name,
+        await flet_app.page.take_screenshot(
+            pixel_ratio=flet_app.screenshots_pixel_ratio
+        ),
+    )
+
+
+@pytest.mark.asyncio(loop_scope="module")
+async def test_simple_action(flet_app: ftt.FletTestApp, request):
+    flet_app.page.enable_screenshots = True
+    flet_app.resize_page(500, 300)
+    flet_app.page.show_dialog(ft.SnackBar(ft.Text("Directory deleted."), action="Undo"))
+    flet_app.page.update()
+    await flet_app.tester.pump_and_settle()
+
+    flet_app.assert_screenshot(
+        request.node.name,
+        await flet_app.page.take_screenshot(
+            pixel_ratio=flet_app.screenshots_pixel_ratio
+        ),
+    )
+
+
+@pytest.mark.asyncio(loop_scope="module")
+async def test_custom_action(flet_app: ftt.FletTestApp, request):
+    flet_app.page.enable_screenshots = True
+    flet_app.resize_page(500, 300)
+    flet_app.page.show_dialog(
+        ft.SnackBar(
+            ft.Text("File deleted."),
+            action=ft.SnackBarAction(
+                label="Undo delete",
+                text_color=ft.Colors.YELLOW,
+                bgcolor=ft.Colors.BLUE,
+            ),
+        )
+    )
+    flet_app.page.update()
+    await flet_app.tester.pump_and_settle()
+
+    flet_app.assert_screenshot(
+        request.node.name,
         await flet_app.page.take_screenshot(
             pixel_ratio=flet_app.screenshots_pixel_ratio
         ),