How to declare a directive globally for all modules in Angular?

问题

I'm developing a Github repo which follows the offical tutorial of Angular (Tour of Heroes). You can see all the code here: https://github.com/Ismaestro/angular7-example-app

My problem, is that I have a directive declared in the main module of the app (app.module) and if I use it inside the AppComponent it works good (the directive only highlight a text inside a DOM element).

But I have another module called HeroesModule within AppModule, and inside a component of this module, this directive doesn't work. The main code, here:

app/app.module.ts

...

import { HighlightDirective } from "./shared/highlight.directive";

@NgModule({
    imports: [
        BrowserModule,
        FormsModule,
        HttpModule,
        InMemoryWebApiModule.forRoot(InMemoryDataService),
        AppRoutingModule,
        CoreModule,
        HeroesModule
    ],
    declarations: [
        AppComponent,
        HeroTopComponent,
        HighlightDirective <-------
    ],
    providers: [
        { provide: APP_CONFIG, useValue: AppConfig }
    ],
    bootstrap: [ AppComponent ]
})

...

app/heroes/heroes.module.ts

@NgModule({
    imports: [
        CommonModule,
        FormsModule,
        HeroRoutingModule
    ],
    declarations: [
        HeroListComponent,
        HeroSearchComponent,
        HeroDetailComponent,
        HeroFormComponent
    ],
    providers: [
        HeroService
    ],
    exports: [
        HeroSearchComponent
    ]
})

app/shared/highlight.directive.ts

import { Directive, ElementRef, Input } from '@angular/core';

@Directive({ selector: '[tohHighlight]' })

export class HighlightDirective {
    constructor(el: ElementRef) {
        el.nativeElement.style.backgroundColor = 'yellow';
    }
}

app/app.component.ts

<h1 tohHighlight>{{title}}</h1> <----- HERE WORKS
<toh-nav></toh-nav>
<router-outlet></router-outlet>

app/heroes/hero-list/hero-list.component.ts

<div *ngIf="selectedHero">
    <h2>
        {{selectedHero.name | uppercase}} is my hero
    </h2>
    <p tohHighlight>Test</p> <----- HERE IT DOESN'T
    <button (click)="gotoDetail()">View Details</button>
</div>

You can see, install it and test it by yourself in the Github repo, if you need it.

Thanks!

回答1:

Example: Plunker

If you need component/directive to use everywhere. you should create a new module:

if you use angular-cli you can generate:

ng g module my-common

the module:

@NgModule({
 declarations: [MyCommonComponent],
 exports:[MyCommonComponent]
})
export class MyCommonModule{}

important! the exports allow you to use the components/directives outside the module.

the component/directive:

@Component({
  selector: 'common-component',
  template: `<h1> common component</h1>`
})
export class MyCommonComponent{}

Finally, you can import that module everywhere you need, you can put it on AppModule, it allow you to use it everywhere on your app.

for example:

@NgModule({
  imports: [MyCommonModule]
})
export class AppModule{}

Good Luck!

回答2:

According @CrazyMac's comment, a good way would be to create a DirectivesModule. Inside this module you can declare and import all your directives then you will be able to import this module anywhere you want.

app/modules/directives/directives.module.ts

import { NgModule } from '@angular/core';
import { HighlightDirective } from './highlight.directive';

@NgModule({
  imports: [],
  declarations: [HighlightDirective],
  exports: [HighlightDirective]
})
export class DirectivesModule { }

app/modules/directives/highLight.directive.ts

import { Directive, ElementRef } from '@angular/core';

@Directive({ selector: '[myHighlight]' })
export class HighlightDirective {
  constructor(el: ElementRef) {
    el.nativeElement.style.backgroundColor = 'yellow';
  }
}

app/modules/otherModule/other-module.module.ts

import { DirectivesModule } from '../directives/directives.module';

@NgModule({
  imports: [
    DirectivesModule
  ],
  declarations: []
})
export class OtherModule { }

来源：https://stackoverflow.com/questions/41505392/how-to-declare-a-directive-globally-for-all-modules-in-angular