feat(component-store): Add SelectorObject to select

modules/component-store/spec/component-store.spec.ts

@@ -1,43 +1,43 @@
 /* eslint-disable @typescript-eslint/no-non-null-assertion */
+import {
+  Inject,
+  Injectable,
+  InjectionToken,
+  Injector,
+  Provider,
+} from '@angular/core';
+import { fakeAsync, flushMicrotasks } from '@angular/core/testing';
 import {
   ComponentStore,
   OnStateInit,
   OnStoreInit,
   provideComponentStore,
 } from '@ngrx/component-store';
-import { fakeSchedulers, marbles } from 'rxjs-marbles/jest';
+import { createSelector } from '@ngrx/store';
 import {
-  of,
-  Subscription,
+  asyncScheduler,
   ConnectableObservable,
+  from,
   interval,
-  timer,
   Observable,
-  from,
-  scheduled,
+  of,
   queueScheduler,
-  asyncScheduler,
+  scheduled,
+  Subscription,
   throwError,
+  timer,
 } from 'rxjs';
+import { fakeSchedulers, marbles } from 'rxjs-marbles/jest';
 import {
+  concatMap,
+  delay,
   delayWhen,
+  finalize,
+  map,
   publishReplay,
   take,
-  map,
   tap,
-  finalize,
-  delay,
-  concatMap,
 } from 'rxjs/operators';
-import { createSelector } from '@ngrx/store';
-import {
-  Inject,
-  Injectable,
-  InjectionToken,
-  Injector,
-  Provider,
-} from '@angular/core';
-import { fakeAsync, flushMicrotasks } from '@angular/core/testing';
 
 describe('Component Store', () => {
   describe('initialization', () => {
@@ -432,7 +432,7 @@ describe('Component Store', () => {
   });
 
   describe('cancels updater Observable', () => {
-    beforeEach(() => jest.useFakeTimers());
+    beforeEach(() => jest.useFakeTimers({ legacyFakeTimers: true }));
 
     interface State {
       value: string;
@@ -809,6 +809,80 @@ describe('Component Store', () => {
       ]);
     });
 
+    it('can combine into an object through selectorObject', () => {
+      const selector1 = componentStore.select((s) => s.value);
+      const selector2 = componentStore.select((s) => s.updated);
+      const selector3 = componentStore.select({
+        s1: selector1,
+        s2: selector2,
+      });
+
+      const selectorResults: Array<{
+        s1: string;
+        s2: boolean | undefined;
+      }> = [];
+      selector3.subscribe((s3) => {
+        selectorResults.push(s3);
+      });
+
+      componentStore.setState(() => ({ value: 'new value', updated: true }));
+
+      expect(selectorResults).toEqual([
+        { s1: 'init', s2: undefined },
+        { s1: 'new value', s2: undefined }, // not debounced
+        { s1: 'new value', s2: true },
+      ]);
+    });
+
+    it('can combine into an object through a single selectorObject', () => {
+      const selector1 = componentStore.select((s) => s.value);
+
+      const selector2 = componentStore.select({
+        s1: selector1,
+      });
+
+      const selectorResults: Array<{
+        s1: string;
+      }> = [];
+      selector2.subscribe((s2) => {
+        selectorResults.push(s2);
+      });
+
+      componentStore.setState(() => ({ value: 'new value', updated: true }));
+
+      expect(selectorResults).toEqual([{ s1: 'init' }, { s1: 'new value' }]);
+    });
+
+    it('can combine into an object through selectorObject with debounce', fakeAsync(() => {
+      const selector1 = componentStore.select((s) => s.value);
+      const selector2 = componentStore.select((s) => s.updated);
+      const selector3 = componentStore.select(
+        {
+          s1: selector1,
+          s2: selector2,
+        },
+        { debounce: true }
+      );
+
+      const selectorResults: Array<{
+        s1: string;
+        s2: boolean | undefined;
+      }> = [];
+      selector3.subscribe((s3) => {
+        selectorResults.push(s3);
+      });
+      flushMicrotasks();
+
+      componentStore.setState(() => ({ value: 'new value', updated: true }));
+      flushMicrotasks();
+
+      expect(selectorResults).toEqual([
+        { s1: 'init', s2: undefined },
+        // debounced, so new value for both
+        { s1: 'new value', s2: true },
+      ]);
+    }));
+
     it(
       'can combine with other Observables',
       marbles((m) => {

modules/component-store/src/component-store.ts

@@ -11,6 +11,7 @@ import {
   scheduled,
   asapScheduler,
   EMPTY,
+  ObservedValueOf,
 } from 'rxjs';
 import {
   takeUntil,
@@ -225,46 +226,53 @@ export class ComponentStore<T extends object> implements OnDestroy {
     projector: (s: T) => Result,
     config?: SelectConfig
   ): Observable<Result>;
+  select<SelectorsObject extends Record<string, Observable<unknown>>>(
+    selectorsObject: SelectorsObject,
+    config?: SelectConfig
+  ): Observable<{
+    [K in keyof SelectorsObject]: ObservedValueOf<SelectorsObject[K]>;
+  }>;
   select<Selectors extends Observable<unknown>[], Result>(
-    ...args: [...selectors: Selectors, projector: Projector<Selectors, Result>]
+    ...selectorsWithProjector: [
+      ...selectors: Selectors,
+      projector: Projector<Selectors, Result>
+    ]
   ): Observable<Result>;
   select<Selectors extends Observable<unknown>[], Result>(
-    ...args: [
+    ...selectorsWithProjectorAndConfig: [
       ...selectors: Selectors,
       projector: Projector<Selectors, Result>,
       config: SelectConfig
     ]
   ): Observable<Result>;
   select<
-    Selectors extends Array<Observable<unknown> | SelectConfig | ProjectorFn>,
+    Selectors extends Array<
+      Observable<unknown> | SelectConfig | ProjectorFn | SelectorsObject
+    >,
     Result,
-    ProjectorFn extends (...a: unknown[]) => Result
+    ProjectorFn extends (...a: unknown[]) => Result,
+    SelectorsObject extends Record<string, Observable<unknown>>
   >(...args: Selectors): Observable<Result> {
-    const { observables, projector, config } = processSelectorArgs<
-      Selectors,
-      Result,
-      ProjectorFn
-    >(args);
-
-    let observable$: Observable<Result>;
-    // If there are no Observables to combine, then we'll just map the value.
-    if (observables.length === 0) {
-      observable$ = this.stateSubject$.pipe(
-        config.debounce ? debounceSync() : (source$) => source$,
-        map((state) => projector(state))
-      );
-    } else {
-      // If there are multiple arguments, then we're aggregating selectors, so we need
-      // to take the combineLatest of them before calling the map function.
-      observable$ = combineLatest(observables).pipe(
-        config.debounce ? debounceSync() : (source$) => source$,
-        map((projectorArgs) => projector(...projectorArgs))
+    const { observablesOrSelectorsObject, projector, config } =
+      processSelectorArgs<Selectors, Result, ProjectorFn, SelectorsObject>(
+        args
       );
-    }
 
-    return observable$.pipe(
+    const source$ = hasProjectFnOnly(observablesOrSelectorsObject, projector)
+      ? this.stateSubject$
+      : combineLatest(observablesOrSelectorsObject as any);
+
+    return source$.pipe(
+      config.debounce ? debounceSync() : noopOperator(),
+      (projector
+        ? map((projectorArgs) =>
+            Array.isArray(projectorArgs)
+              ? projector(...projectorArgs)
+              : projector(projectorArgs)
+          )
+        : noopOperator()) as () => Observable<Result>,
       distinctUntilChanged(),
-      shareReplay({
+      shareReplay<Result>({
         refCount: true,
         bufferSize: 1,
       }),
@@ -357,36 +365,70 @@ export class ComponentStore<T extends object> implements OnDestroy {
 }
 
 function processSelectorArgs<
-  Selectors extends Array<Observable<unknown> | SelectConfig | ProjectorFn>,
+  Selectors extends Array<
+    Observable<unknown> | SelectConfig | ProjectorFn | SelectorsObject
+  >,
   Result,
-  ProjectorFn extends (...a: unknown[]) => Result
+  ProjectorFn extends (...a: unknown[]) => Result,
+  SelectorsObject extends Record<string, Observable<unknown>>
 >(
   args: Selectors
-): {
-  observables: Observable<unknown>[];
-  projector: ProjectorFn;
-  config: Required<SelectConfig>;
-} {
+):
+  | {
+      observablesOrSelectorsObject: Observable<unknown>[];
+      projector: ProjectorFn;
+      config: Required<SelectConfig>;
+    }
+  | {
+      observablesOrSelectorsObject: SelectorsObject;
+      projector: undefined;
+      config: Required<SelectConfig>;
+    } {
   const selectorArgs = Array.from(args);
   // Assign default values.
   let config: Required<SelectConfig> = { debounce: false };
-  let projector: ProjectorFn;
-  // Last argument is either projector or config
-  const projectorOrConfig = selectorArgs.pop() as ProjectorFn | SelectConfig;
-
-  if (typeof projectorOrConfig !== 'function') {
-    // We got the config as the last argument, replace any default values with it.
-    config = { ...config, ...projectorOrConfig };
-    // Pop the next args, which would be the projector fn.
-    projector = selectorArgs.pop() as ProjectorFn;
-  } else {
-    projector = projectorOrConfig;
+
+  // Last argument is either config or projector or selectorsObject
+  if (isSelectConfig(selectorArgs[selectorArgs.length - 1])) {
+    config = { ...config, ...selectorArgs.pop() };
   }
-  // The Observables to combine, if there are any.
+
+  // At this point selectorArgs is either projector, selectors with projector or selectorsObject
+  if (selectorArgs.length === 1 && typeof selectorArgs[0] !== 'function') {
+    // this is a selectorsObject
+    return {
+      observablesOrSelectorsObject: selectorArgs[0] as SelectorsObject,
+      projector: undefined,
+      config,
+    };
+  }
+
+  const projector = selectorArgs.pop() as ProjectorFn;
+
+  // The Observables to combine, if there are any left.
   const observables = selectorArgs as Observable<unknown>[];
   return {
-    observables,
+    observablesOrSelectorsObject: observables,
     projector,
     config,
   };
 }
+
+function isSelectConfig(arg: SelectConfig | unknown): arg is SelectConfig {
+  return typeof (arg as SelectConfig).debounce !== 'undefined';
+}
+
+function hasProjectFnOnly(
+  observablesOrSelectorsObject: unknown[] | Record<string, unknown>,
+  projector: unknown
+) {
+  return (
+    Array.isArray(observablesOrSelectorsObject) &&
+    observablesOrSelectorsObject.length === 0 &&
+    projector
+  );
+}
+
+function noopOperator(): <T>(source$: Observable<T>) => typeof source$ {
+  return (source$) => source$;
+}