Updating componentPath from the DashWrapper setProps

CHANGELOG.md

@@ -2,6 +2,11 @@
 All notable changes to `dash` will be documented in this file.
 This project adheres to [Semantic Versioning](https://semver.org/).
 
+## [unreleased]
+
+## Fixed
+- [#3264](https://github.com/plotly/dash/pull/3264) Fixed an issue where moving components inside of children would not update the `setProps` path, leading to hashes being incorrect
+
 ## [3.0.2] - 2025-04-01
 
 ## Changed

dash/dash-renderer/src/wrapper/DashWrapper.tsx

@@ -65,6 +65,7 @@ function DashWrapper({
     const dispatch = useDispatch();
     const memoizedKeys: MutableRefObject<MemoizedKeysType> = useRef({});
     const newRender = useRef(false);
+    const renderedPath = useRef<DashLayoutPath>(componentPath);
     let renderComponent: any = null;
     let renderComponentProps: any = null;
     let renderH: any = null;
@@ -90,6 +91,7 @@ function DashWrapper({
         } else {
             newRender.current = false;
         }
+        renderedPath.current = componentPath;
     }, [_newRender]);
 
     const setProps = (newProps: UpdatePropsPayload) => {
@@ -101,7 +103,10 @@ function DashWrapper({
         dispatch((dispatch, getState) => {
             const currentState = getState();
             const {graphs} = currentState;
-            const oldLayout = getComponentLayout(componentPath, currentState);
+            const oldLayout = getComponentLayout(
+                renderedPath.current,
+                currentState
+            );
             if (!oldLayout) return;
             const {props: oldProps} = oldLayout;
             if (!oldProps) return;
@@ -144,7 +149,7 @@ function DashWrapper({
                 dispatch(
                     updateProps({
                         props: changedProps,
-                        itempath: componentPath,
+                        itempath: renderedPath.current,
                         renderType: 'internal'
                     })
                 );

tests/integration/renderer/test_children_reorder.py

@@ -0,0 +1,89 @@
+from dash import Dash, Input, Output, html, dcc, State, ALL
+
+
+class Section:
+    def __init__(self, idx):
+        self.idx = idx
+        self.options = ["A", "B", "C"]
+
+    @property
+    def section_id(self):
+        return {"type": "section-container", "id": self.idx}
+
+    @property
+    def dropdown_id(self):
+        return {"type": "dropdown", "id": self.idx}
+
+    @property
+    def swap_btn_id(self):
+        return {"type": "swap-btn", "id": self.idx}
+
+    def get_layout(self) -> html.Div:
+        layout = html.Div(
+            id=self.section_id,
+            children=[
+                html.H1(f"I am section {self.idx}"),
+                html.Button(
+                    "SWAP",
+                    id=self.swap_btn_id,
+                    n_clicks=0,
+                    className=f"swap_button_{self.idx}",
+                ),
+                dcc.Dropdown(
+                    self.options,
+                    id=self.dropdown_id,
+                    multi=True,
+                    value=[],
+                    className=f"dropdown_{self.idx}",
+                ),
+            ],
+        )
+        return layout
+
+
+def test_roc001_reorder_children(dash_duo):
+    app = Dash()
+
+    app.layout = html.Div(
+        id="main-app", children=[*[Section(idx=i).get_layout() for i in range(2)]]
+    )
+
+    @app.callback(
+        Output("main-app", "children"),
+        Input({"type": "swap-btn", "id": ALL}, "n_clicks"),
+        State("main-app", "children"),
+        prevent_initial_call=True,
+    )
+    def swap_button_action(n_clicks, children):
+        if any(n > 0 for n in n_clicks):
+            return children[::-1]
+
+    dash_duo.start_server(app)
+
+    for i in range(2):
+        dash_duo.wait_for_text_to_equal("h1", f"I am section {i}")
+        dash_duo.wait_for_text_to_equal(
+            f".dropdown_{i} .Select-multi-value-wrapper", "Select..."
+        )
+        dash_duo.find_element(f".dropdown_{i}").click()
+        dash_duo.find_element(f".dropdown_{i} .VirtualizedSelectOption").click()
+        dash_duo.wait_for_text_to_equal(
+            f".dropdown_{i} .Select-multi-value-wrapper", "×A\n "
+        )
+        dash_duo.find_element(f".dropdown_{i}").click()
+        dash_duo.find_element(f".dropdown_{i} .VirtualizedSelectOption").click()
+        dash_duo.wait_for_text_to_equal(
+            f".dropdown_{i} .Select-multi-value-wrapper", "×A\n ×B\n "
+        )
+        dash_duo.find_element(f".dropdown_{i}").click()
+        dash_duo.find_element(f".dropdown_{i} .VirtualizedSelectOption").click()
+        dash_duo.wait_for_text_to_equal(
+            f".dropdown_{i} .Select-multi-value-wrapper", "×A\n ×B\n ×C\n "
+        )
+        dash_duo.find_element(f".swap_button_{i}").click()
+    dash_duo.wait_for_text_to_equal(
+        f".dropdown_{0} .Select-multi-value-wrapper", "×A\n ×B\n ×C\n "
+    )
+    dash_duo.wait_for_text_to_equal(
+        f".dropdown_{1} .Select-multi-value-wrapper", "×A\n ×B\n ×C\n "
+    )