feat: add with-connect feature

apps/demo/src/app/app.component.html

@@ -26,6 +26,7 @@
       <a mat-list-item routerLink="/immutable-state">withImmutableState</a>
       <a mat-list-item routerLink="/feature-factory">withFeatureFactory</a>
       <a mat-list-item routerLink="/conditional">withConditional</a>
+      <a mat-list-item routerLink="/connect">withConnect</a>
     </mat-nav-list>
   </mat-drawer>
   <mat-drawer-content>

apps/demo/src/app/connect/connect.component.ts

@@ -0,0 +1,41 @@
+import { Component, inject, linkedSignal } from '@angular/core';
+import { signalStore, withState } from '@ngrx/signals';
+import { FormsModule } from '@angular/forms';
+import { withConnect } from '@angular-architects/ngrx-toolkit';
+
+const initialState = { user: { name: 'Max' } };
+
+const UserStore = signalStore(
+  { providedIn: 'root' },
+  withState(initialState),
+  withConnect()
+);
+
+@Component({
+  template: `
+    <h2>
+      <pre>withConnect</pre>
+    </h2>
+    <p>
+      withConnect() adds a method to connect Signals back to your store.
+      Everytime these Signals change, the store will be updated accordingly.
+    </p>
+
+    <p>User name in Store: {{ userStore.user.name() }}</p>
+
+    <p>Connected local user name: <input [(ngModel)]="userName" /></p>
+  `,
+  imports: [FormsModule],
+})
+export class ConnectComponent {
+  protected readonly userStore = inject(UserStore);
+  protected readonly userName = linkedSignal(() => this.userStore.user.name());
+
+  constructor() {
+    this.userStore.connect(() => ({
+      user: {
+        name: this.userName(),
+      },
+    }));
+  }
+}

apps/demo/src/app/lazy-routes.ts

@@ -61,4 +61,9 @@ export const lazyRoutes: Route[] = [
         (m) => m.ConditionalSettingComponent
       ),
   },
+  {
+    path: 'connect',
+    loadComponent: () =>
+      import('./connect/connect.component').then((m) => m.ConnectComponent),
+  },
 ];

docs/docs/with-connect.md

@@ -0,0 +1,52 @@
+---
+title: withConnect()
+---
+
+```typescript
+import { withConnect } from '@angular-architects/ngrx-toolkit';
+```
+
+`withConnect()` adds a method to connect Signals back to your store. Everytime these Signals change, the store will be updated accordingly.
+
+Example:
+
+```ts
+const Store = signalStore(
+  { protectedState: false },
+  withState({
+    maxWarpFactor: 8,
+    shipName: 'USS Enterprise',
+    registration: 'NCC-1701',
+    poeple: 430,
+  }),
+  withConnect()
+);
+```
+
+```ts
+@Component({ ... })
+export class MyComponent {
+  private store = inject(OfferListStore);
+
+  readonly maxWarpFactor = signal(8);
+  readonly registration = signal('NCC-1701');
+  readonly people = signal(430);
+
+  constructor() {
+    //
+    // Every change in the local Signals is
+    // refected in the store
+    //
+    this.store.connect(() => ({
+        //
+        // Subset of state in the store
+        //
+        maxWarpFactor: this.maxWarpFactor(),
+        registration: this.registration(),
+        poeple: this.poeple(),
+    }));
+  }
+
+  ...
+}
+```

docs/sidebars.ts

@@ -26,6 +26,7 @@ const sidebars: SidebarsConfig = {
     'with-feature-factory',
     'with-conditional',
     'with-call-state',
+    'with-connect',
   ],
   reduxConnectorSidebar: [
     {

libs/ngrx-toolkit/src/index.ts

@@ -41,3 +41,4 @@ export {
 } from './lib/storage-sync/with-storage-sync';
 export { emptyFeature, withConditional } from './lib/with-conditional';
 export { withFeatureFactory } from './lib/with-feature-factory';
+export * from './lib/with-connect';

libs/ngrx-toolkit/src/lib/with-connect.spec.ts

@@ -0,0 +1,61 @@
+import { getState, patchState, signalStore, withState } from '@ngrx/signals';
+import { fakeAsync, TestBed, tick } from '@angular/core/testing';
+import { signal } from '@angular/core';
+import { withConnect } from './with-connect';
+
+describe('withConnect', () => {
+  const setup = () => {
+    const Store = signalStore(
+      { protectedState: false },
+      withState({
+        maxWarpFactor: 8,
+        shipName: 'USS Enterprise',
+        registration: 'NCC-1701',
+        poeple: 430,
+      }),
+      withConnect('maxWarpFactor', 'registration', 'poeple')
+    );
+
+    const store = TestBed.configureTestingModule({
+      providers: [Store],
+    }).inject(Store);
+
+    return { store };
+  };
+
+  it('should update store after connected signals are changed', fakeAsync(() => {
+    const { store } = setup();
+
+    TestBed.runInInjectionContext(() => {
+      const maxWarpFactor = signal(9);
+      const registration = signal('NCC-1701-D');
+      const poeple = signal(1100);
+
+      store.connect(() => ({
+        maxWarpFactor: maxWarpFactor(),
+        registration: registration(),
+        poeple: poeple(),
+      }));
+      tick(1);
+      expect(getState(store)).toMatchObject({
+        maxWarpFactor: 9,
+        shipName: 'USS Enterprise',
+        registration: 'NCC-1701-D',
+        poeple: 1100,
+      });
+
+      maxWarpFactor.set(9.6);
+      tick(1);
+      expect(getState(store).maxWarpFactor).toBeCloseTo(9.6);
+      expect(getState(store).shipName).toEqual('USS Enterprise');
+
+      patchState(store, { maxWarpFactor: 9.2 });
+      tick(1);
+      expect(getState(store).maxWarpFactor).toBeCloseTo(9.2);
+      expect(getState(store).shipName).toEqual('USS Enterprise');
+
+      // It's just a one-way-sync
+      expect(maxWarpFactor()).toBeCloseTo(9.6);
+    });
+  }));
+});

libs/ngrx-toolkit/src/lib/with-connect.ts

@@ -0,0 +1,55 @@
+import { computed } from '@angular/core';
+import {
+  EmptyFeatureResult,
+  patchState,
+  signalMethod,
+  SignalStoreFeature,
+  signalStoreFeature,
+  SignalStoreFeatureResult,
+  withMethods,
+} from '@ngrx/signals';
+
+export type WithConnectResultType<
+  T extends SignalStoreFeatureResult,
+  K extends keyof T['state']
+> = EmptyFeatureResult & {
+  methods: {
+    connect(state: () => Partial<Pick<T['state'], K>>): void;
+  };
+};
+
+export function withConnect<
+  T extends SignalStoreFeatureResult,
+  Keys extends readonly (keyof T['state'])[]
+>(
+  ...keys: Keys
+): SignalStoreFeature<T, WithConnectResultType<T, Keys[number]>> {
+  return signalStoreFeature(
+    withMethods((store) => {
+      return {
+        connect(stateFn: () => Partial<Pick<T['state'], Keys[number]>>): void {
+          const stateSignal = computed(stateFn);
+
+          // TypeScript allows additional keys
+          validateKeys(stateFn, keys);
+
+          signalMethod<Partial<Pick<T['state'], Keys[number]>>>((state) => {
+            patchState(store, state);
+          })(stateSignal);
+        },
+      };
+    })
+  );
+}
+
+function validateKeys<
+  T extends SignalStoreFeatureResult,
+  Keys extends readonly (keyof T['state'])[]
+>(stateFn: () => Partial<Pick<T['state'], Keys[number]>>, keys: Keys) {
+  const candKeys = Object.keys(stateFn()) as unknown as Keys;
+  for (const key of candKeys) {
+    if (!keys.includes(key)) {
+      throw new Error(`Key ${String(key)} is not provided via withConnect!`);
+    }
+  }
+}