1. 概述
NgRx 是 Angular 应用中实现全局状态管理的 Redux 架构解决方案
- @ngrx/store：全局状态管理模块
- @ngrx/effects：处理副作用
- @ngrx/store-devtools：浏览器调试工具，需要依赖 Redux Devtools Extension
- @ngrx/schematics：命令行工具，快速生成
NgRx文件- @ngrx/entity：提高开发者在
Reducer中操作数据的效率- @ngrx/router-store：将路由状态同步到全局
Store
2. 快速开始
-
下载
NgRxnpm install @ngrx/store @ngrx/effects @ngrx/entity @ngrx/router-store @ngrx/store-devtools @ngrx/schematics -
配置
NgRx CLIng config cli.defaultCollection @ngrx/schematics// angular.json "cli": { "defaultCollection": "@ngrx/schematics" } -
创建
Storeng g store State --root --module app.module.ts --statePath store --stateInterface AppState -
创建
Actionng g action store/actions/counter --skipTestsimport { createAction } from "@ngrx/store" export const increment = createAction("increment") export const decrement = createAction("decrement") -
创建
Reducerng g reducer store/reducers/counter --skipTests --reducers=../index.tsimport { createReducer, on } from "@ngrx/store" import { decrement, increment } from "../actions/counter.actions" export const counterFeatureKey = "counter" export interface State { count: number } export const initialState: State = { count: 0 } export const reducer = createReducer( initialState, on(increment, state => ({ count: state.count + 1 })), on(decrement, state => ({ count: state.count - 1 })) ) -
创建
Selectorng g selector store/selectors/counter --skipTestsimport { createFeatureSelector, createSelector } from "@ngrx/store" import { counterFeatureKey, State } from "../reducers/counter.reducer" import { AppState } from ".." export const selectCounter = createFeatureSelector<AppState, State>(counterFeatureKey) export const selectCount = createSelector(selectCounter, state => state.count) -
组件类触发
Action、获取状态import { select, Store } from "@ngrx/store" import { Observable } from "rxjs" import { AppState } from "./store" import { decrement, increment } from "./store/actions/counter.actions" import { selectCount } from "./store/selectors/counter.selectors" export class AppComponent { count: Observable<number> constructor(private store: Store<AppState>) { this.count = this.store.pipe(select(selectCount)) } increment() { this.store.dispatch(increment()) } decrement() { this.store.dispatch(decrement()) } } -
组件模板显示状态
<button (click)="increment()">+</button> <span>{{ count | async }}</span> <button (click)="decrement()">-</button>
3. Action Payload
-
在组件中使用
dispatch触发Action时传递参数，参数最终会被放置在Action对象中this.store.dispatch(increment({ count: 5 })) -
在创建
Action Creator函数时，获取参数并指定参数类型。import { createAction, props } from "@ngrx/store" export const increment = createAction("increment", props<{ count: number }>())export declare function props<P extends object>(): Props<P>; -
在
Reducer中通过Action对象获取参数。export const reducer = createReducer( initialState, on(increment, (state, action) => ({ count: state.count + action.count })) )
4. MetaReducer
metaReducer 是 Action -> Reducer 之间的钩子，允许开发者对 Action 进行预处理 (在普通 Reducer 函数调用之前调用)
function debug(reducer: ActionReducer<any>): ActionReducer<any> {
return function (state, action) {
return reducer(state, action)
}
}
export const metaReducers: MetaReducer<AppState>[] = !environment.production
? [debug]
: []
5. Effect
需求：在页面中新增一个按钮，点击按钮后延迟一秒让数值增加
-
在组件模板中新增一个用于异步数值增加的按钮，按钮被点击后执行
increment_async方法<button (click)="increment_async()">async</button> -
在组件类中新增
increment_async方法，并在方法中触发执行异步操作的Actionincrement_async() { this.store.dispatch(increment_async()) } -
在 Action 文件中新增执行异步操作的
Actionexport const increment_async = createAction("increment_async") -
创建
Effect，接收Action并执行副作用，继续触发Actionng g effect store/effects/counter --root --module app.module.ts --skipTestsEffect功能由@ngrx/effects模块提供，所以在根模块中需要导入相关的模块依赖import { Injectable } from "@angular/core" import { Actions, createEffect, ofType } from "@ngrx/effects" import { increment, increment_async } from "../actions/counter.actions" import { mergeMap, map } from "rxjs/operators" import { timer } from "rxjs" // createEffect // 用于创建 Effect, Effect 用于执行副作用. // 调用方法时传递回调函数, 回调函数中返回 Observable 对象, 对象中要发出副作用执行完成后要触发的 Action 对象 // 回调函数的返回值在 createEffect 方法内部被继续返回, 最终返回值被存储在了 Effect 类的属性中 // NgRx 在实例化 Effect 类后, 会订阅 Effect 类属性, 当副作用执行完成后它会获取到要触发的 Action 对象并触发这个 Action // Actions // 当组件触发 Action 时, Effect 需要通过 Actions 服务接收 Action, 所以在 Effect 类中通过 constructor 构造函数参数的方式将 Actions 服务类的实例对象注入到 Effect 类中 // Actions 服务类的实例对象为 Observable 对象, 当有 Action 被触发时, Action 对象本身会作为数据流被发出 // ofType // 对目标 Action 对象进行过滤. // 参数为目标 Action 的 Action Creator 函数 // 如果未过滤出目标 Action 对象, 本次不会继续发送数据流 // 如果过滤出目标 Action 对象, 会将 Action 对象作为数据流继续发出 @Injectable() export class CounterEffects { constructor(private actions: Actions) { // this.loadCount.subscribe(console.log) } loadCount = createEffect(() => { return this.actions.pipe( ofType(increment_async), mergeMap( () => timer(1000) .pipe( map(() => increment({ count: 10 })) ) ) ) }) }
6. Entity
6.1 概述
Entity 译为实体，实体就是集合中的一条数据
NgRx 中提供了实体适配器对象，在实体适配器对象下面提供了各种操作集合中实体的方法，目的就是提高开发者操作实体的效率
6.2 核心
-
EntityState：实体类型接口
/* { ids: [1, 2], entities: { 1: { id: 1, title: "Hello Angular" }, 2: { id: 2, title: "Hello NgRx" } } } */ export interface State extends EntityState<Todo> {} createEntityAdapter： 创建实体适配器对象
-
EntityAdapter：实体适配器对象类型接口
export const adapter: EntityAdapter<Todo> = createEntityAdapter<Todo>() // 获取初始状态 可以传递对象参数 也可以不传 // {ids: [], entities: {}} export const initialState: State = adapter.getInitialState()
6.3 实例方法
6.4 选择器
// selectTotal 获取数据条数
// selectAll 获取所有数据 以数组形式呈现
// selectEntities 获取实体集合 以字典形式呈现
// selectIds 获取id集合, 以数组形式呈现
const { selectIds, selectEntities, selectAll, selectTotal } = adapter.getSelectors();
export const selectTodo = createFeatureSelector<AppState, State>(todoFeatureKey)
export const selectTodos = createSelector(selectTodo, selectAll)
7. Router Store
7.1 同步路由状态
-
引入模块
import { StoreRouterConnectingModule } from "@ngrx/router-store" @NgModule({ imports: [ StoreRouterConnectingModule.forRoot() ] }) export class AppModule {} -
将路由状态集成到
Storeimport * as fromRouter from "@ngrx/router-store" export interface AppState { router: fromRouter.RouterReducerState } export const reducers: ActionReducerMap<AppState> = { router: fromRouter.routerReducer }
7.2 创建获取路由状态的 Selector
// router.selectors.ts
import { createFeatureSelector } from "@ngrx/store"
import { AppState } from ".."
import { RouterReducerState, getSelectors } from "@ngrx/router-store"
const selectRouter = createFeatureSelector<AppState, RouterReducerState>(
"router"
)
export const {
// 获取和当前路由相关的信息 (路由参数、路由配置等)
selectCurrentRoute,
// 获取地址栏中 # 号后面的内容
selectFragment,
// 获取路由查询参数
selectQueryParams,
// 获取具体的某一个查询参数 selectQueryParam('name')
selectQueryParam,
// 获取动态路由参数
selectRouteParams,
// 获取某一个具体的动态路由参数 selectRouteParam('name')
selectRouteParam,
// 获取路由自定义数据
selectRouteData,
// 获取路由的实际访问地址
selectUrl
} = getSelectors(selectRouter)
// home.component.ts
import { select, Store } from "@ngrx/store"
import { AppState } from "src/app/store"
import { selectQueryParams } from "src/app/store/selectors/router.selectors"
export class AboutComponent {
constructor(private store: Store<AppState>) {
this.store.pipe(select(selectQueryParams)).subscribe(console.log)
}
}
