fix(router): fix navigation when clearing history and navigating before the navigatedTo event fires (#100)

* fix(router): fix navigation when clearing history and navigating before the navigatedTo event fires

* fix: mark cache for clearing for better consistency

Author: edusperoni

packages/angular/src/lib/legacy/router/ns-route-reuse-strategy.ts

@@ -9,6 +9,7 @@ interface CacheItem {
   key: string;
   state: DetachedRouteHandle;
   isModal: boolean;
+  markedForDeletion?: boolean;
 }
 
 const getSnapshotKey = function (snapshot: ActivatedRouteSnapshot): string {
@@ -52,6 +53,28 @@ class DetachedStateCache {
     }
   }
 
+  public markCurrentForClear() {
+    for (const item of this.cache) {
+      item.markedForDeletion = true;
+    }
+  }
+
+  public clearMarked() {
+    // try to preserve same order as .clear()
+    for (let i = this.cache.length - 1; i >= 0; i--) {
+      const cacheItem = this.cache[i];
+      if (cacheItem.markedForDeletion) {
+        const state = <any>cacheItem.state;
+        if (!state.componentRef) {
+          throw new Error('No componentRef found in DetachedRouteHandle');
+        }
+
+        destroyComponentRef(state.componentRef);
+        this.cache.splice(i, 1);
+      }
+    }
+  }
+
   public clearModalCache() {
     let removedItemsCount = 0;
     const hasModalPages = this.cache.some((cacheItem) => {
@@ -259,6 +282,14 @@ export class NSRouteReuseStrategy implements RouteReuseStrategy {
     }
   }
 
+  markCacheForClear(outletKey: string) {
+    const cache = this.cacheByOutlet[outletKey];
+
+    if (cache) {
+      cache.markCurrentForClear();
+    }
+  }
+
   popCache(outletKey: string) {
     const cache = this.cacheByOutlet[outletKey];
 
@@ -272,6 +303,25 @@ export class NSRouteReuseStrategy implements RouteReuseStrategy {
     }
   }
 
+  markCacheForPop(outletKey: string) {
+    const cache = this.cacheByOutlet[outletKey];
+
+    if (cache) {
+      const item = cache.peek();
+      if (item) {
+        item.markedForDeletion = true;
+      }
+    }
+  }
+
+  clearMarkedCache(outletKey: string) {
+    const cache = this.cacheByOutlet[outletKey];
+
+    if (cache) {
+      cache.clearMarked();
+    }
+  }
+
   clearModalCache(outletKey: string) {
     const cache = this.cacheByOutlet[outletKey];
 

packages/angular/src/lib/legacy/router/page-router-outlet.ts

@@ -29,6 +29,17 @@ function isComponentFactoryResolver(item: any): item is ComponentFactoryResolver
   return !!item.resolveComponentFactory;
 }
 
+function callableOnce<T>(fn: (...args: T[]) => void) {
+  let called = false;
+  return (...args: T[]) => {
+    if (called) {
+      return;
+    }
+    called = true;
+    return fn(...args);
+  };
+}
+
 export class DestructibleInjector implements Injector {
   private refs = new Set<any>();
   constructor(private destructibleProviders: ProviderSet, private parent: Injector) {}
@@ -79,6 +90,10 @@ export class PageRouterOutlet implements OnDestroy, RouterOutletContract {
   private isEmptyOutlet: boolean;
   private viewUtil: ViewUtil;
   private frame: Frame;
+  // this function is used to clear the outlet cache (clear history)
+  // usually it's cleared in `navigatedTo`, but on quick navigation, the event will be fired after angular already added more things to the cache
+  // so now we call this if the component is detached or deactivated (meaning it's mid-navigation, before cache manipulation)
+  private postNavFunction: () => void;
 
   attachEvents: EventEmitter<unknown> = new EventEmitter();
   detachEvents: EventEmitter<unknown> = new EventEmitter();
@@ -217,6 +232,7 @@ export class PageRouterOutlet implements OnDestroy, RouterOutletContract {
     if (!this.isActivated) {
       return;
     }
+    this.postNavFunction?.();
 
     const c = this.activated.instance;
     destroyComponentRef(this.activated);
@@ -242,6 +258,8 @@ export class PageRouterOutlet implements OnDestroy, RouterOutletContract {
       NativeScriptDebug.routerLog(`PageRouterOutlet.detach() - ${routeToString(this._activatedRoute)}`);
     }
 
+    this.postNavFunction?.();
+
     // Detach from ChangeDetection
     this.activated.hostView.detach();
 
@@ -421,28 +439,45 @@ export class PageRouterOutlet implements OnDestroy, RouterOutletContract {
     this.locationStrategy._beginPageNavigation(this.frame, navOptions);
     const isReplace = navOptions.replaceUrl && !navOptions.clearHistory;
 
+    const currentRoute = this.activatedRoute;
     // Clear refCache if navigation with clearHistory
     if (navOptions.clearHistory) {
+      this.outlet.outletKeys.forEach((key) => this.routeReuseStrategy.markCacheForClear(key));
+      const wipeCache = callableOnce(() => {
+        if (this.postNavFunction === wipeCache) {
+          this.postNavFunction = null;
+        }
+        if (this.outlet && this.activatedRoute === currentRoute) {
+          // potential alternative fix (only fix children of the current outlet)
+          // const nests = outletKey.split('/');
+          // this.outlet.outletKeys.filter((k) => k.split('/').length >= nests.length).forEach((key) => this.routeReuseStrategy.clearCache(key));
+          this.outlet.outletKeys.forEach((key) => this.routeReuseStrategy.clearMarkedCache(key));
+        }
+      });
+      this.postNavFunction = wipeCache;
       const clearCallback = () =>
         setTimeout(() => {
-          if (this.outlet) {
-            // potential alternative fix (only fix children of the current outlet)
-            // const nests = outletKey.split('/');
-            // this.outlet.outletKeys.filter((k) => k.split('/').length >= nests.length).forEach((key) => this.routeReuseStrategy.clearCache(key));
-            this.outlet.outletKeys.forEach((key) => this.routeReuseStrategy.clearCache(key));
-          }
+          wipeCache();
         });
 
       page.once(Page.navigatedToEvent, clearCallback);
     } else if (navOptions.replaceUrl) {
+      this.outlet.outletKeys.forEach((key) => this.routeReuseStrategy.markCacheForPop(key));
+      const popCache = callableOnce(() => {
+        if (this.postNavFunction === popCache) {
+          this.postNavFunction = null;
+        }
+        if (this.outlet && this.activatedRoute === currentRoute) {
+          // potential alternative fix (only fix children of the current outlet)
+          // const nests = outletKey.split('/');
+          // this.outlet.outletKeys.filter((k) => k.split('/').length >= nests.length).forEach((key) => this.routeReuseStrategy.popCache(key));
+          this.outlet.outletKeys.forEach((key) => this.routeReuseStrategy.clearMarkedCache(key));
+        }
+      });
+      this.postNavFunction = popCache;
       const clearCallback = () =>
         setTimeout(() => {
-          if (this.outlet) {
-            // potential alternative fix (only fix children of the current outlet)
-            // const nests = outletKey.split('/');
-            // this.outlet.outletKeys.filter((k) => k.split('/').length >= nests.length).forEach((key) => this.routeReuseStrategy.popCache(key));
-            this.outlet.outletKeys.forEach((key) => this.routeReuseStrategy.popCache(key));
-          }
+          popCache();
         });
 
       page.once(Page.navigatedToEvent, clearCallback);