在 app.module 中注册减速器在 angular ngrx 状态管理中显示错误

Question

我正在 Angular 12 和最新的 NgRx 库中创建一个应用程序用于教程目的。我有以下模型、动作、reducer 和应用程序状态 class。

型号

export interface Tutorial {
  name: string;
  url: string;
}

操作数

import { Injectable } from '@angular/core'
import { Action } from '@ngrx/store'
import { Tutorial } from '../_models/tutorial.model'

export const ADD_TUTORIAL       = '[TUTORIAL] Add'
export const REMOVE_TUTORIAL    = '[TUTORIAL] Remove'

export class AddTutorial implements Action {
    readonly type = ADD_TUTORIAL

    constructor(public payload: Tutorial) {}
}

export class RemoveTutorial implements Action {
    readonly type = REMOVE_TUTORIAL
    
    constructor(public payload: number) {}
}

export type Actions = AddTutorial | RemoveTutorial

减速器

import { Action } from '@ngrx/store'
import { Tutorial } from '../_models/tutorial.model';
import * as TutorialActions from './../_actions/tutorial.actions'

const initialState: Tutorial = {
    name: 'Initial Tutorial',
    url: 'http://google.com'
}

export function reducer(state: Tutorial[] = [initialState], action: TutorialActions.Actions) {
    switch(action.type) {
        case TutorialActions.ADD_TUTORIAL:
            return [...state, action.payload];
        default:
            return state;
    }
}

应用状态

import { Tutorial } from "./_models/tutorial.model";

export interface AppState {
    readonly tutorial: Tutorial[];
}

现在我想在app.module.ts文件中导入reducer。这是代码：

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { AppRoutingModule } from './app-routing.module';
import { AppComponent } from './app.component';
import { StoreModule } from '@ngrx/store';
import { reducer } from './_reducers/tutorial.reducer';
import { ReadComponent } from './read/read.component';
import { CreateComponent } from './create/create.component';

@NgModule({
   declarations: [
      AppComponent,
      ReadComponent,
      CreateComponent
   ],
   imports: [
      BrowserModule,
      StoreModule.forRoot({ tutorial: reducer }),
      AppRoutingModule,
   ],
   providers: [],
   bootstrap: [
      AppComponent
   ]
})
export class AppModule { }

但是在app.module.ts文件中，导入reducer出错。错误如下图：

Error: src/app/app.module.ts:19:29 - error TS2322: Type '(state: Tutorial[] | undefined, action: Actions) => Tutorial[]' is not assignable to type 'ActionReducer<Tutorial[], Action>'. Types of parameters 'action' and 'action' are incompatible. Type 'Action' is not assignable to type 'Actions'. Property 'payload' is missing in type 'Action' but required in type 'RemoveTutorial'.

19 StoreModule.forRoot({ tutorial: reducer }), ~~~~~~~~

src/app/_actions/tutorial.actions.ts:20:17 20 constructor(public payload: number) {} ~~~~~~~~~~~~~~~~~~~~~~ 'payload' is declared here.

由于我是 NgRx 的新手，我不明白为什么会出现这个问题。请帮我解决问题。

Answer 1

我已经有一段时间没有使用该语法了，它可能是一个回归错误。您可以将其断言为 ActionReducerMap

StoreModule.forRoot({ tutorial: reducer } as ActionReducerMap<any,any>)

此外，我建议看一下 createAction 和 createReducer 语法 - 它使事情变得更简单。

在 app.module 中注册减速器在 angular ngrx 状态管理中显示错误

Registering reducer in app.module shows error in angular ngrx state management

angular

ngrx

ngrx-reducers