NgZone或ApplicationRef注入到角度组件中

Question

我有两个组件：A和B。组件B是A的子组件。我将一个函数从A传递给B，以访问和更新B中A的一些属性。当我这样做时，Angular不会重新渲染(如果我从A调用相同的函数，它将会重新渲染)。

为了解决这个问题，我在其run中注入了NgZone来进行更新，但它不会被注入。我用ApplicationRef和ChangeDetectorRef尝试了同样的方法，但它们都没有被注入(我得到了Cannot read property 'run' of undefined)。

A.component.ts

@Component({
  selector: 'app-A',
  templateUrl: './A.component.html',
})
export class AComponent implements OnInit {
  someList: BModel[];

  constructor(
    private ngZone: NgZone,
    private fooClient: FooService,
    private barService: barService,
  ) {}

  ngOnInit() {}

  setFlag(enabled: boolean) {
    console.log(`flag was set to ${enabled}`);
    this.flag = enabled;
    this.ngZone.run(() => this.flag = enabled);
  }
}

A.component.html

<app-B [setFlag]="setFlag"></app-B>

B.component.ts

@Component({
  selector: 'app-B',
  templateUrl: './B.component.html',
})
export class BComponent implements OnInit {
  @Input() setFlag: (_: boolean) => void;

  constructor(private fooClient: FooService) {}

  ngOnInit() {}

  submit() {
    this.setFlag(false);
  }
}

我在日志中看到该函数正在被调用，但Angular不会重新呈现，并且ngZone为undefined。使用注释器@Inject(NgZone)或者在JiT/AoT或dev/prod之间切换都不能解决这个问题。

依赖关系：

  "dependencies": {
    "@angular/animations": "^8.2.14",
    "@angular/cdk": "^8.2.3",
    "@angular/common": "^8.2.14",
    "@angular/compiler": "^8.2.14",
    "@angular/core": "^8.2.14",
    "@angular/forms": "^8.2.14",
    "@angular/material": "^8.2.3",
    "@angular/platform-browser": "^8.2.14",
    "@angular/platform-browser-dynamic": "^8.2.14",
    "@angular/router": "^8.2.14",
    "@types/change-case": "^2.3.1",
    "capital-case": "^1.0.3",
    "change-case": "^4.1.1",
    "rxjs": "~6.4.0",
    "rxjs-compat": "^6.5.4",
    "tslib": "^1.10.0",
    "uuid": "^7.0.3",
    "zone.js": "~0.9.1"
  },
  "devDependencies": {
    "@angular-devkit/build-angular": "^0.803.25",
    "@angular/cli": "~8.3.4",
    "@angular/compiler-cli": "^8.2.14",
    "@angular/language-service": "^8.2.14",
    "@types/jasmine": "~3.3.8",
    "@types/jasminewd2": "^2.0.8",
    "@types/node": "~8.9.4",
    "codelyzer": "^5.2.1",
    "handlebars": "^4.7.6",
    "jasmine-core": "~3.4.0",
    "jasmine-spec-reporter": "~4.2.1",
    "karma": "^4.4.1",
    "karma-chrome-launcher": "~2.2.0",
    "karma-coverage-istanbul-reporter": "^2.1.1",
    "karma-jasmine": "~2.0.1",
    "karma-jasmine-html-reporter": "^1.5.2",
    "prettier": "^1.19.1",
    "protractor": "^5.4.3",
    "ts-node": "~7.0.0",
    "tslint": "~5.15.0",
    "typescript": "~3.5.3"
  },

Answer 1

您应该使用@Output()和EventEmitter在子组件和父组件之间进行通信。这样，您就可以离开变更检测和ngZone了。指南里有一个tutorial。

组件类：

export class AComponent {
  onSetFlag(enabled: boolean) {
    console.log(`flag was set to ${enabled}`);
    this.flag = enabled;
  }
}

组件模板：

<app-b (setFlag)="onSetFlag(flag)"></app-b>

B组件类：

export class BComponent {
  @Output() setFlag= new EventEmitter<boolean>();
  onSubmit(){
    setFlag.next(true);
  }
}