如何在angular组件中从ngrx存储中获取内容

// app.state.ts
import { createAction, createReducer, on } from '@ngrx/store';

export interface AppState {
  content: string;
}

export const initialState: AppState = {
  content: ''
};

export const getContent = createAction('[Content] Get Content');

export const contentReducer = createReducer(
  initialState,
  on(getContent, state => state)
);

// content.component.ts
import { Component, OnInit } from '@angular/core';
import { Store, select } from '@ngrx/store';
import { getContent } from 'app.state';

@Component({
  selector: 'app-content',
  templateUrl: './content.component.html',
  styleUrls: ['./content.component.css']
})
export class ContentComponent implements OnInit {
  content: string;

  constructor(private store: Store<{ app: AppState }>) {}

  ngOnInit() {
    this.store.dispatch(getContent());
    this.store.pipe(select('app')).subscribe(state => {
      this.content = state.content;
    });
  }
}