feat(component-store): add patchState method

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

@@ -83,6 +83,36 @@ describe('Component Store', () => {
  })
  );
 
+ it('throws an Error when patchState with an object is called before initialization', () => {
+ const componentStore = new ComponentStore();
+
+ expect(() => {
+ componentStore.patchState({ foo: 'bar' });
+ }).toThrow(
+ new Error(
+ 'ComponentStore has not been initialized yet. ' +
+ 'Please make sure it is initialized before updating/getting.'
+ )
+ );
+ });
+
+ it(
+ 'throws an Error when patchState with a function/callback is called' +
+ ' before initialization',
+ () => {
+ const componentStore = new ComponentStore();
+
+ expect(() => {
+ componentStore.patchState(() => ({ foo: 'bar' }));
+ }).toThrow(
+ new Error(
+ 'ComponentStore has not been initialized yet. ' +
+ 'Please make sure it is initialized before updating/getting.'
+ )
+ );
+ }
+ );
+
  it(
  'throws an Error when updater is called before initialization',
  marbles((m) => {
@@ -511,6 +541,47 @@ describe('Component Store', () => {
  );
  });
 
+ describe('patches the state', () => {
+ interface State {
+ value1: string;
+ value2: { foo: string };
+ }
+ const INIT_STATE: State = { value1: 'value1', value2: { foo: 'bar' } };
+ let componentStore: ComponentStore<State>;
+
+ beforeEach(() => {
+ componentStore = new ComponentStore(INIT_STATE);
+ });
+
+ it(
+ 'with a specific value',
+ marbles((m) => {
+ componentStore.patchState({ value1: 'val1' });
+
+ m.expect(componentStore.state$).toBeObservable(
+ m.hot('s', {
+ s: { ...INIT_STATE, value1: 'val1' },
+ })
+ );
+ })
+ );
+
+ it(
+ 'with a value based on the previous state',
+ marbles((m) => {
+ componentStore.patchState((state) => ({
+ value2: { foo: `${state.value2.foo}2` },
+ }));
+
+ m.expect(componentStore.state$).toBeObservable(
+ m.hot('s', {
+ s: { ...INIT_STATE, value2: { foo: 'bar2' } },
+ })
+ );
+ })
+ );
+ });
+
  describe('selector', () => {
  interface State {
  value: string;

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

@@ -156,6 +156,29 @@ export class ComponentStore<T extends object> implements OnDestroy {
  }
  }
 
+ /**
+ * Patches the state with provided partial state.
+ *
+ * @param partialStateOrUpdaterFn a partial state or a partial updater
+ * function that accepts the state and returns the partial state.
+ * @throws Error if the state is not initialized.
+ */
+ patchState(
+ partialStateOrUpdaterFn: Partial<T> | ((state: T) => Partial<T>)
+ ): void {
+ this.setState((state) => {
+ const patchedState =
+ typeof partialStateOrUpdaterFn === 'function'
+ ? partialStateOrUpdaterFn(state)
+ : partialStateOrUpdaterFn;
+
+ return {
+ ...state,
+ ...patchedState,
+ };
+ });
+ }
+
  protected get(): T;
  protected get<R>(projector: (s: T) => R): R;
  protected get<R>(projector?: (s: T) => R): R | T {