Tips for including multiple directives in a component

Question

Tips for including multiple directives in a component

Apologies in advance for my lack of clarity in expressing this question, which is why I am seeking assistance rather than finding the solution on my own.

My query pertains to loading a component within another one and specifying it in the directive. Below is a brief example I created from scratch as I am struggling with the correct syntax:

http://plnkr.co/edit/gFsqGJmmayOsewL3EfLf

import {Component} from 'angular2/core'
import {Prueba} from './prueba'

@Component({
  selector: 'my-app',
  providers: [],
  template: `
    <div>
      <h2>Hello {{name}}</h2>
      <prueba></prueba>      
    </div>
  `,
  directives: [Prueba]
})
export class App {
  constructor() {
    this.name = 'Angular2'
  }
}

In the app.ts file, you'll notice there is a directive inside the component, without which the code fails to work properly. Although I am not entirely sure why, this is how I have been taught.

My objective now is to implement multiple components, such as Prueba along with an additional one that includes extra content (initially just another "phrase," but eventually akin to http://plnkr.co/edit/SVPNwk?p=preview). Unfortunately, no matter what I attempt, I experience issues with the syntax, causing even this basic example to fail.

I admit to being confused about what key concepts I might be overlooking. Despite importing and using the new component's selector, the application consistently encounters errors. What fundamental understanding eludes me?

If my explanation remains inadequate, I am referring to the theoretical concept outlined here:

angular.io/docs/ts/latest/cheatsheet.html (I cannot post more than two links... anyway its the @Component part, that's the documentation I'm consulting).

javascript typescript angular plunker

Answer 1

Answer №1

When working with Angular2, it's important to understand the distinction between a component and a directive:

A component combines a template (view) with properties and functionality (the component class)
There are two types of directives:
- Attribute directive, which modifies the appearance or behavior of a DOM element
- Structural directive, which alters the layout of the DOM by adding or removing elements

You can use a component within another component by specifying its selector. This needs to be explicitly defined in the directives attribute of the parent component. The directives attribute can contain both components and directives and allows you to pass parameters to a component and respond to its events.

For example:

Sub component

@Component({
  selector: 'sub',
  template: `
    <div>Sub</div>
  `
})
export class SubComponent {
}

Parent component:

@Component({
  selector: 'comp',
  template: `
    <div>
      <sub></sub>
    </div>
  `,
  directives: [ SubComponent, AnotherComponent ]
})
export class ContainerComponent {
}

A directive applies to an existing element based on its selector.

For instance:

Custom Directive

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

Parent component:

@Component({
  selector: 'comp',
  template: `
    <div dir>Some text</div>
  `,
  directives: [ DirDirective ]
})
export class ContainerComponent {
}

The directives attribute

It is important to note that the directives attribute must include any custom components or directives that are not part of the platform. Failure to do so will result in the component/directive not being applied.

This attribute can accept multiple values as it is an array:

@Component({
  selector: 'comp',
  template: `
    <div>
      <sub></sub>
      <another></another>
    </div>
  `,
  directives: [ SubComponent, AnotherComponent ]
})
export class ContainerComponent {
}

Answer 2

When working with Angular2, it's important to understand the distinction between a component and a directive:

A component combines a template (view) with properties and functionality (the component class)
There are two types of directives:
- Attribute directive, which modifies the appearance or behavior of a DOM element
- Structural directive, which alters the layout of the DOM by adding or removing elements

You can use a component within another component by specifying its selector. This needs to be explicitly defined in the directives attribute of the parent component. The directives attribute can contain both components and directives and allows you to pass parameters to a component and respond to its events.

For example:

Sub component

@Component({
  selector: 'sub',
  template: `
    <div>Sub</div>
  `
})
export class SubComponent {
}

Parent component:

@Component({
  selector: 'comp',
  template: `
    <div>
      <sub></sub>
    </div>
  `,
  directives: [ SubComponent, AnotherComponent ]
})
export class ContainerComponent {
}

A directive applies to an existing element based on its selector.

For instance:

Custom Directive

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

Parent component:

@Component({
  selector: 'comp',
  template: `
    <div dir>Some text</div>
  `,
  directives: [ DirDirective ]
})
export class ContainerComponent {
}

The directives attribute

It is important to note that the directives attribute must include any custom components or directives that are not part of the platform. Failure to do so will result in the component/directive not being applied.

This attribute can accept multiple values as it is an array:

@Component({
  selector: 'comp',
  template: `
    <div>
      <sub></sub>
      <another></another>
    </div>
  `,
  directives: [ SubComponent, AnotherComponent ]
})
export class ContainerComponent {
}

Tips for including multiple directives in a component

Answer №1

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