refactor: discard all routes but last when getting action from state

example/src/index.tsx

@@ -124,7 +124,8 @@ export default function App() {
     prefixes: LinkingPrefixes,
     config: {
       Root: {
-        path: 'root',
+        path: '',
+        initialRouteName: 'Home',
         screens: Object.keys(SCREENS).reduce<{ [key: string]: string }>(
           (acc, name) => {
             // Convert screen names such as SimpleStack to kebab case (simple-stack)
@@ -135,7 +136,7 @@ export default function App() {
 
             return acc;
           },
-          {}
+          { Home: '' }
         ),
       },
     },

packages/core/src/__tests__/getActionFromState.test.tsx

@@ -41,10 +41,9 @@ it('gets navigate action from state', () => {
     },
     type: 'NAVIGATE',
   });
-});
 
-it('gets reset action from state', () => {
-  const state = {
+  expect(
+    getActionFromState({
       routes: [
         {
           name: 'foo',
@@ -66,10 +65,40 @@ it('gets reset action from state', () => {
           },
         },
       ],
-  };
-
-  expect(getActionFromState(state)).toEqual({
-    payload: state,
-    type: 'RESET_ROOT',
+    })
+  ).toEqual({
+    payload: {
+      name: 'foo',
+      params: {
+        screen: 'bar',
+        params: {
+          screen: 'quz',
+        },
+      },
+    },
+    type: 'NAVIGATE',
   });
 });
+
+it('gets reset action from state', () => {
+  const state = {
+    routes: [
+      {
+        name: 'foo',
+        state: {
+          routes: [
+            {
+              name: 'bar',
+              state: {
+                routes: [],
+              },
+            },
+          ],
+        },
+      },
+    ],
+  };
+
+  expect(getActionFromState(state)).toBe(undefined);
+  expect(getActionFromState({ routes: [] })).toBe(undefined);
+});

packages/core/src/getActionFromState.tsx

@@ -5,37 +5,36 @@ type NavigateParams = {
   params?: NavigateParams;
 };
 
-type Action =
-  | {
+type NavigateAction = {
   type: 'NAVIGATE';
   payload: { name: string; params: NavigateParams };
-    }
-  | {
-      type: 'RESET_ROOT';
-      payload: PartialState<NavigationState>;
-    };
+};
 
 export default function getActionFromState(
   state: PartialState<NavigationState>
-): Action {
-  let payload: { name: string; params: NavigateParams } | undefined;
+): NavigateAction | undefined {
+  if (state.routes.length === 0) {
+    return undefined;
+  }
 
-  if (state.routes.length === 1) {
   // Try to construct payload for a `NAVIGATE` action from the state
   // This lets us preserve the navigation state and not lose it
-    let route = state.routes[0];
+  let route = state.routes[state.routes.length - 1];
 
-    payload = {
+  let payload: { name: string; params: NavigateParams } = {
     name: route.name,
     params: { ...route.params },
   };
 
-    let current = state.routes[0].state;
+  let current = route.state;
   let params = payload.params;
 
   while (current) {
-      if (current.routes.length === 1) {
-        route = current.routes[0];
+    if (current.routes.length === 0) {
+      return undefined;
+    }
+
+    route = current.routes[current.routes.length - 1];
     params.screen = route.name;
 
     if (route.state) {
@@ -46,22 +45,10 @@ export default function getActionFromState(
     }
 
     current = route.state;
-      } else {
-        payload = undefined;
-        break;
-      }
-    }
   }
 
-  if (payload) {
   return {
     type: 'NAVIGATE',
     payload,
   };
-  }
-
-  return {
-    type: 'RESET_ROOT',
-    payload: state,
-  };
 }

packages/native/src/useLinking.native.tsx

@@ -76,10 +76,10 @@ export default function useLinking(
         if (state) {
           const action = getActionFromState(state);
 
-          if (action.type === 'RESET_ROOT') {
-            navigation.resetRoot(action.payload);
-          } else {
+          if (action !== undefined) {
             navigation.dispatch(action);
+          } else {
+            navigation.resetRoot(state);
           }
         }
       }

packages/native/src/useLinking.tsx

@@ -162,10 +162,10 @@ export default function useLinking(
 
           pendingStateUpdateRef.current = true;
 
-          if (action.type === 'RESET_ROOT') {
-            navigation.resetRoot(action.payload);
-          } else {
+          if (action !== undefined) {
             navigation.dispatch(action);
+          } else {
+            navigation.resetRoot(state);
           }
         }
       }