feat(signals): add patch function and remove $update method

ngrx · Sep 4, 2023 · 11c517d · 11c517d
1 parent eeadd3f
commit 11c517d
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Showing 4 changed files with 50 additions and 53 deletions.
diff --git a/modules/signals/spec/signal-state.spec.ts b/modules/signals/spec/signal-state.spec.ts
@@ -1,5 +1,5 @@
 import { effect, isSignal } from '@angular/core';
-import { signalState } from '../src';
+import { patch, signalState } from '../src';
 import { testEffects } from './helpers';
 
 describe('signalState', () => {
@@ -13,11 +13,11 @@ describe('signalState', () => {
     ngrx: 'signals',
   };
 
-  describe('$update', () => {
+  describe('patch', () => {
     it('updates state via partial state object', () => {
       const state = signalState(initialState);
 
-      state.$update({
+      patch(state, {
         user: { firstName: 'Johannes', lastName: 'Schmidt' },
         foo: 'baz',
       });
@@ -32,7 +32,7 @@ describe('signalState', () => {
     it('updates state via updater function', () => {
       const state = signalState(initialState);
 
-      state.$update((state) => ({
+      patch(state, (state) => ({
         numbers: [...state.numbers, 4],
         ngrx: 'rocks',
       }));
@@ -47,7 +47,8 @@ describe('signalState', () => {
     it('updates state via sequence of partial state objects and updater functions', () => {
       const state = signalState(initialState);
 
-      state.$update(
+      patch(
+        state,
         { user: { firstName: 'Johannes', lastName: 'Schmidt' } },
         (state) => ({ numbers: [...state.numbers, 4], foo: 'baz' }),
         (state) => ({ user: { ...state.user, firstName: 'Jovan' } }),
@@ -65,7 +66,7 @@ describe('signalState', () => {
     it('updates state immutably', () => {
       const state = signalState(initialState);
 
-      state.$update({
+      patch(state, {
         foo: 'bar',
         numbers: [3, 2, 1],
         ngrx: 'rocks',
@@ -149,14 +150,14 @@ describe('signalState', () => {
         expect(userEmitted).toBe(1);
         expect(firstNameEmitted).toBe(1);
 
-        state.$update({ numbers: [1, 2, 3] });
+        patch(state, { numbers: [1, 2, 3] });
         tick();
 
         expect(numbersEmitted).toBe(2);
         expect(userEmitted).toBe(1);
         expect(firstNameEmitted).toBe(1);
 
-        state.$update((state) => ({
+        patch(state, (state) => ({
           user: { ...state.user, lastName: 'Schmidt' },
         }));
         tick();
@@ -165,7 +166,7 @@ describe('signalState', () => {
         expect(userEmitted).toBe(2);
         expect(firstNameEmitted).toBe(1);
 
-        state.$update((state) => ({
+        patch(state, (state) => ({
           user: { ...state.user, firstName: 'Johannes' },
         }));
         tick();

diff --git a/modules/signals/src/index.ts b/modules/signals/src/index.ts
@@ -1,3 +1,2 @@
 export { selectSignal } from './select-signal';
-export { signalState } from './signal-state';
-export { SignalStateUpdater } from './signal-state-models';
+export { patch, signalState, SignalStateUpdater } from './signal-state';
diff --git a/modules/signals/src/signal-state-models.ts b/modules/signals/src/signal-state-models.ts
diff --git a/modules/signals/src/signal-state.ts b/modules/signals/src/signal-state.ts
@@ -1,34 +1,52 @@
 import { signal, WritableSignal } from '@angular/core';
-import { toDeepSignal } from './deep-signal';
+import { DeepSignal, toDeepSignal } from './deep-signal';
 import { defaultEqual } from './select-signal';
-import {
-  NotAllowedStateCheck,
-  SignalState,
-  SignalStateUpdate,
-} from './signal-state-models';
+
+type SignalState<State extends Record<string, unknown>> = DeepSignal<State> &
+  SignalStateMeta<State>;
+
+const SIGNAL_STATE_META_KEY = Symbol('SIGNAL_STATE_META_KEY');
+
+type SignalStateMeta<State extends Record<string, unknown>> = {
+  [SIGNAL_STATE_META_KEY]: WritableSignal<State>;
+};
+
+/**
+ * Signal state cannot contain optional properties.
+ */
+type NotAllowedStateCheck<State> = State extends Required<State>
+  ? State extends Record<string, unknown>
+    ? { [K in keyof State]: State[K] & NotAllowedStateCheck<State[K]> }
+    : unknown
+  : never;
+
+export type SignalStateUpdater<State extends Record<string, unknown>> =
+  | Partial<State>
+  | ((state: State) => Partial<State>);
 
 export function signalState<State extends Record<string, unknown>>(
   initialState: State & NotAllowedStateCheck<State>
 ): SignalState<State> {
   const stateSignal = signal(initialState as State, { equal: defaultEqual });
   const deepSignal = toDeepSignal(stateSignal.asReadonly());
-  (deepSignal as SignalState<State>).$update =
-    signalStateUpdateFactory(stateSignal);
+  Object.defineProperty(deepSignal, SIGNAL_STATE_META_KEY, {
+    value: stateSignal,
+  });
 
   return deepSignal as SignalState<State>;
 }
 
-export function signalStateUpdateFactory<State extends Record<string, unknown>>(
-  stateSignal: WritableSignal<State>
-): SignalStateUpdate<State>['$update'] {
-  return (...updaters) =>
-    stateSignal.update((state) =>
-      updaters.reduce(
-        (currentState: State, updater) => ({
-          ...currentState,
-          ...(typeof updater === 'function' ? updater(currentState) : updater),
-        }),
-        state
-      )
-    );
+export function patch<State extends Record<string, unknown>>(
+  signalState: SignalStateMeta<State>,
+  ...updaters: SignalStateUpdater<State>[]
+): void {
+  signalState[SIGNAL_STATE_META_KEY].update((currentState) =>
+    updaters.reduce(
+      (nextState: State, updater) => ({
+        ...nextState,
+        ...(typeof updater === 'function' ? updater(nextState) : updater),
+      }),
+      currentState
+    )
+  );
 }