Directive cannot be used as an entry component in Angular 2

Question

I am doing an Angular 2 demo with injection and get an error that my CustomDirective can't be used as an entry element.

So, my NgModule

    import {platformBrowserDynamic} from '@angular/platform-browser-dynamic';
import AppComponent from  './app.component';
import {NgModule} from "@angular/core";

@NgModule({
    declarations: [AppComponent],
    bootstrap:[AppComponent]
})
export class AppModule{}



const platform = platformBrowserDynamic();
platform.bootstrapModule(AppModule);

AppComponent:

import {Component} from '@angular/core';
import {TIMER_DIRECTIVES} from './timer/timer';
import {TASK_DIRECTIVES} from './tasks/tasks';
import {SHARED_PROVIDERS} from './shared/shared';


@Component({
    selector: 'tomato-app',
    entryComponents: [TIMER_DIRECTIVES,TASK_DIRECTIVES],
    providers: [SHARED_PROVIDERS],
    template: `
        <nav class="navbar navbar-default navbar-static-top">
            <div class="container">
                <div class="navbar-header">
                    <strong class="navbar-brand">Tomato App</strong>
                </div>
            </div>
        </nav>
        <tomato-timer-widget></tomato-timer-widget>
        <tomato-tasks></tomato-tasks>`
})
export default class AppComponent{}

And the custom directive itself:

import {Task} from '../shared/shared'
import {Input, HostListener, Directive} from '@angular/core';


@Directive({
    selector: '[task]'
})
export default class TaskTooltipDirective {
    private defaultTooltipText: string;
    @Input() task: Task;
    @Input() taskTooltip: any;

    @HostListener('mouseover')
    onMouseOver() {
        if (!this.defaultTooltipText && this.taskTooltip) {
            this.defaultTooltipText = this.taskTooltip.innerText;
        }
        this.taskTooltip.innerText = this.task.name;
    }

    @HostListener('mouseout')
    onMouseOut() {
        if (this.taskTooltip) {
            this.taskTooltip.innerText = this.defaultTooltipText;
        }
    }
}

The problem is that I am using entryComponents in AppComponent incorrectly. How do I need to link a custom directive?

Answer 1

entryComponents: list of components that are dynamically inserted into the view of this component

How do I need to link a custom directive? Put your all directive, pipe, component in declarations array at NgModule level:

@NgModule({
    declarations: [AppComponent, TIMER_DIRECTIVES, TASK_DIRECTIVES],
    bootstrap:[AppComponent]
})
export class AppModule{}

note that, if you declare provider at Component level:

@Component({
    selector: 'tomato-app',
    providers: [SHARED_PROVIDERS],
    //...
})

it will create new instance for all instances of this component. in other word, if you have 2 different Component, with 2 declare providers: [SHARED_PROVIDERS], then the SHARED_PROVIDERS of 2 component are different. you need declare in NgModule level to use same instance in all component of this NgModule.

@NgModule({
    declarations: [AppComponent, TIMER_DIRECTIVES, TASK_DIRECTIVES],
    providers: [SHARED_PROVIDERS],
    entryComponents: [TIMER_DIRECTIVES, TASK_DIRECTIVES],
    bootstrap:[AppComponent]
})
export class AppModule{}