7

我整天都在努力让我的 Angular 应用程序与 ngrx/store 4 一起工作。经过很多不成功的小时后，我决定创建一个新的绝对最小的应用程序来检查我是否还有其他问题。但是最小的应用程序根本不起作用:(

在我可以看到的 Chrome Redux devtools 中，商店已正确更新。但是UI没有更新。app.component.ts ( this.age$.subscribe(console.log)) 中的日志语句也永远不会执行。我真的不知道我错过了什么。

这是相关的代码。

包.json

{
  "dependencies": {
    "@angular/animations": "^4.2.4",
    "@angular/common": "^4.2.4",
    "@angular/compiler": "^4.2.4",
    "@angular/core": "^4.2.4",
    "@angular/forms": "^4.2.4",
    "@angular/http": "^4.2.4",
    "@angular/platform-browser": "^4.2.4",
    "@angular/platform-browser-dynamic": "^4.2.4",
    "@angular/router": "^4.2.4",
    "@ngrx/store": "^4.0.2",
    "@ngrx/store-devtools": "^4.0.0",
    "rxjs": "^5.4.2",
    "zone.js": "^0.8.14"
  },
  "devDependencies": {
    "@types/node": "^8.0.22",
    "typescript": "^2.4.2"
  }
}

app.module.ts

import { AppState } from './state';
import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { StoreModule } from '@ngrx/store';
import { StoreDevtoolsModule } from '@ngrx/store-devtools'
import { reducer } from './reducer';

import { AppComponent } from './app.component';

@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    BrowserModule,
    StoreModule.forRoot({ reducer }),
    StoreDevtoolsModule.instrument(),
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

状态.ts

export interface AppState {
  age: number
}

export const INITIAL_STATE: AppState = {
  age: 1
}

动作.ts

import { Action } from '@ngrx/store';

export const ACTION_TYPE = 'CHANGE_AGE_ACTION';

export class ChangeAgeAction implements Action {
  readonly type: string = ACTION_TYPE;

  constructor(public payload?: number) {
  }
}

减速器.ts

import { ChangeAgeAction } from './actions';
import { Action } from '@ngrx/store';
import { AppState, INITIAL_STATE } from './state';
import { ACTION_TYPE } from './actions';

function changeName(state: AppState, action: ChangeAgeAction): AppState {
  return {
    age: action.payload
  }
}

export function reducer(state: AppState = INITIAL_STATE, action: Action) {
  switch (action.type) {
    case ACTION_TYPE:
      return changeName(state, action);

    default:
      return state;
  }
}

app.component.ts

import { ChangeAgeAction } from './actions';
import { AppState } from './state';
import { Component } from '@angular/core';
import { Observable } from 'rxjs/Observable';
import { Store } from '@ngrx/store';
import { map } from 'rxjs/operator/map';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  age$: Observable<number>;

  constructor(private store: Store<AppState>) {
    this.age$ = this.store.select<number>(state => state.age);
    this.age$.subscribe(console.log);
  }

  changeAge() {
    this.store.dispatch(new ChangeAgeAction(Math.random()));
  }
}

app.component.html

<h3>Age: {{ age$ | async }}</h3>
<button (click)="changeAge()">Change Age</button>
4

2 回答 2

11

您的应用状态未正确建模。实际上有一个包含您的年龄的减速器对象。这是我为使应用程序正常工作所做的更改：

在 state.ts

export interface AppState {
  reducer: {
    age: number
  }
}

在应用程序组件中：

export class AppComponent {
  age$: Observable<number>;

  constructor(private store: Store<AppState>) {
    this.age$ = this.store.select<number>(state => state.reducer.age);
    this.age$.subscribe(console.log);
  }

  changeAge() {
    this.store.dispatch(new ChangeAgeAction(Math.random()));
  }
}

请注意，您在 AppState 中有“reducer”对象的原因是因为当您设置执行此操作时：StoreModule.forRoot({ reducer }). 它从 reducer 获得“reducer”名称。

换句话说，如果你做了类似的事情，StoreModule.forRoot({ ageReducer })那么你的应用程序状态将如下所示：

export interface AppState {
  ageReducer: {
    age: number
  }
}

这是代码的工作版本：

https://stackblitz.com/edit/angular-jxszwh

于 2017-08-16T00:03:31.440 回答
3

另请注意，如果您使用的是角度异步管道，则无需在 observable 上调用 .subscribe。异步管道处理订阅/取消订阅。

于 2017-11-18T23:44:53.067 回答