如何在减小角度7中订阅状态变化值

Question

我正在使用角度7的redux。我可以将值添加到状态中。但是我该如何订阅状态的更改值。

这是我尝试过的代码

选择器

export const selectProfessionalLearningTeacherFeature =
  createFeatureSelector<any>('professionalLearningTeacher');

export const selectProfessionalLearningTeachers =
  createSelector(selectProfessionalLearningTeacherFeature, (state) => state.professionalLearningTeacher);

运动组件

@Component({
  selector: 'app-sports-practice',
  templateUrl: './sports-practice.component.html',
  styleUrls: ['./sports-practice.component.scss']
})
export class SportsPracticeComponent implements OnInit {


  constructor(private fb: FormBuilder, private professionalLearningService: ProfessionalLearningService,private _store: Store<any>) {
    this._store.select(selectProfessionalLearningTeachers)
  .pipe(takeUntil(this._ngOnDestroy)).subscribe(item => {
    console.log(item);
  });
   }

  ngOnInit() {  }

}

这是我的减速器组件

const meta: any = '';
const ProfessionalLearningTeachers: any = '';
const INITIAL_STATE: any = {
  meta,
  ProfessionalLearningTeachers
}
export function ProfessionalLearningTeacherReducer() {
  return function entityReducer(
    state: any = INITIAL_STATE,
    a: Action,
  ): any {
    const action = a as EntityAPIAction;
    if (!action.meta) {
      return state;
    }
    let itemIndex = -1;

    switch (action.type) {
      case ProfessionalLearningTeacherApiActions.PROFESSIONAL_LEARNING_TEACHER_SAVE_SUCCEEDED:
        return storeProfessionalLearning(state, action);
    }
    return state;
  };
}

function storeProfessionalLearning(state, action): any {
  return Object.assign({}, state, {
    meta: action.meta,
    ProfessionalLearningTeachers: action.payload,
  });
}

状态图

控制台输出

参考

In angular (v5) how do I listen to my apps Redux state object changing?

https://github.com/angular-redux/store/blob/master/articles/select-pattern.md

Answer 1

您可以使用选择器。

professionalLearningTeacher.selectors.ts：

import { createFeatureSelector, createSelector } from '@ngrx/store';

export const selectProfessionalLearningTeacherFeature =
  createFeatureSelector<ProfessionalLearningTeacherState | any>('professionalLearningTeacher');
// 'professionalLearningTeacher' is bad practice, this should be a const

export const selectProfessionalLearningTeachers =
  createSelector(selectProfessionalLearningTeacherFeature, (state) => state.professionalLearningTeachers);

portsPracticeComponent.ts：

@Component({
  selector: 'app-sports-practice',
  templateUrl: './sports-practice.component.html',
  styleUrls: ['./sports-practice.component.scss']
})
export class SportsPracticeComponent implements OnInit {
  professionalLearningTeachers$: Observable<any>;

  constructor(
    private _store: Store<IAppState>
  ) {

  }

  ngOnInit() {
    this.professionalLearningTeachers =  this._store.select(selectProfessionalLearningTeachers)
    .pipe(takeUntil(this._ngOnDestroy));
  }
}

请注意：

• IAppState 是指您的州类型，不确定您的州类型，请进行更改。
• 您使用的是 any 而不是特定的类型，我也用它来进行解释，但是您知道这不是一个好习惯，您应该避免使用 any
• 您不应像“ ProfessionalLearningTeachers”中那样使用大写字母来启动状态道具。