Sending data to child component in Angular 2

Question

Sending data to child component in Angular 2

Is there a way to seamlessly pass attributes from wrapper component to nested component?

When we have

const FIRST_PARTY_OWN_INPUTS = [...];
const FIRST_PARTY_PASSTHROUGH_INPUTS = ['all', 'attrs', 'are', 'passed'];
@Component({
  selector: 'first-party',
  inputs: [...FIRST_PARTY_OWN_INPUTS, ...FIRST_PARTY_PASSTHROUGH_INPUTS],
  template: `
<div>
  <third-party [all]="all" [attrs]="attrs" [are]="are" [passed]="passed"></third-party>
  <first-party-extra></first-party-extra>
</div>
  `,
  directives: [ThirdParty]
})
export class FirstParty { ... }

Could the inputs be translated collectively without listing them in the template?

The provided code aims to replicate Angular 1.x directive functionality:

app.directive('firstParty', function (thirdPartyDirective) {
  const OWN_ATTRS = [...];
  const PASSTHROUGH_ATTRS = Object.keys(thirdPartyDirective[0].scope);

  return {
    scope: ...,
    template: `
<div>
  <third-party></third-party>
  <first-party-extra></first-party-extra>
</div>
    `,
compile: function (element, attrs) {
      const nestedElement = element.find('third-party');

      for (let [normalizedAttr, attr] of Object.entries(attrs.$attr)) {
        if (PASSTHROUGH_ATTRS.includes(normalizedAttr)) {
          nestedElement.attr(attr, normalizedAttr);
        }
      }
    },
    ...
  };
});

angularjs angular typescript

Answer 1

Answer №1

I'm not entirely certain if my implementation is correct, but here it is ( PLUNKER )

const OWN_INPUTS = ['not', 'passthrough'];
const PASSTHROUGH_INPUTS = ['all', 'attrs', 'are', 'passed'];

const generateAttributes(arr) {
   return arr.map(att => '[' + att + '] = "' + att + '"').join(' ');
}


//-------------------------------------------------------//////////////////
import {Component} from '@angular/core'

@Component({
  selector: 'third-party',
  inputs: [...PASSTHROUGH_INPUTS],
  template: `
<div>
  {{all}} , {{attrs}} ,  {{are}} ,  {{passed}}
</div>
  `
})
export class ThirdParty {
}

@Component({
  selector: 'first-party',
  inputs: [...OWN_INPUTS, ...PASSTHROUGH_INPUTS],
  template: `
<div>
  <div>
    {{not}} , {{passthrough}}
  </div>
  <third-party ${generateAttributes(PASSTHROUGH_INPUTS)}></third-party>
  <first-party-extra></first-party-extra>
</div>
  `,
  directives: [ThirdParty]
})
export class FirstParty {
}

@Component({
  selector: 'my-app',
  providers: [],
  template: `
    <div>
      <h2>Hello {{name}}</h2>
      <first-party [not]="'not'" [passthrough]="'passthrough'"  
                   [all]="'all'" [attrs]="'attrs'" [are]="'are'" [passed]="'passed'">
      </first-party>
    </div>
  `,
  directives: [FirstParty]
})
export class App {
  constructor() {
    this.name = 'Angular2 (Release Candidate!)'
  }
}

I hope this helps :)

Answer 2

I'm not entirely certain if my implementation is correct, but here it is ( PLUNKER )

const OWN_INPUTS = ['not', 'passthrough'];
const PASSTHROUGH_INPUTS = ['all', 'attrs', 'are', 'passed'];

const generateAttributes(arr) {
   return arr.map(att => '[' + att + '] = "' + att + '"').join(' ');
}


//-------------------------------------------------------//////////////////
import {Component} from '@angular/core'

@Component({
  selector: 'third-party',
  inputs: [...PASSTHROUGH_INPUTS],
  template: `
<div>
  {{all}} , {{attrs}} ,  {{are}} ,  {{passed}}
</div>
  `
})
export class ThirdParty {
}

@Component({
  selector: 'first-party',
  inputs: [...OWN_INPUTS, ...PASSTHROUGH_INPUTS],
  template: `
<div>
  <div>
    {{not}} , {{passthrough}}
  </div>
  <third-party ${generateAttributes(PASSTHROUGH_INPUTS)}></third-party>
  <first-party-extra></first-party-extra>
</div>
  `,
  directives: [ThirdParty]
})
export class FirstParty {
}

@Component({
  selector: 'my-app',
  providers: [],
  template: `
    <div>
      <h2>Hello {{name}}</h2>
      <first-party [not]="'not'" [passthrough]="'passthrough'"  
                   [all]="'all'" [attrs]="'attrs'" [are]="'are'" [passed]="'passed'">
      </first-party>
    </div>
  `,
  directives: [FirstParty]
})
export class App {
  constructor() {
    this.name = 'Angular2 (Release Candidate!)'
  }
}

I hope this helps :)

Answer 3

Answer №2

Reducing this issue to its core, it is clear that dealing with functions that require numerous parameters can be cumbersome and prone to errors, even without the complexity of Angular2. The dilemma intensifies when there is an intermediate function that has no use for these parameters, forcing them to be passed through unnecessarily. It can become quite frustrating!

To address this challenge, various approaches can be taken. One effective method is to pre-instantiate the inner function and pass it along already equipped with the necessary parameters encapsulated within. A helpful resource on achieving this in Angular 2 using @ViewChild and @ContentChild can be found at . Another strategy involves bundling all pass-through parameters into a single object, simplifying the process by reducing the number of individual parameters that need to be transferred. This approach also streamlines any future additions of parameters since they are already bundled together seamlessly.

Answer 4

Reducing this issue to its core, it is clear that dealing with functions that require numerous parameters can be cumbersome and prone to errors, even without the complexity of Angular2. The dilemma intensifies when there is an intermediate function that has no use for these parameters, forcing them to be passed through unnecessarily. It can become quite frustrating!

To address this challenge, various approaches can be taken. One effective method is to pre-instantiate the inner function and pass it along already equipped with the necessary parameters encapsulated within. A helpful resource on achieving this in Angular 2 using @ViewChild and @ContentChild can be found at . Another strategy involves bundling all pass-through parameters into a single object, simplifying the process by reducing the number of individual parameters that need to be transferred. This approach also streamlines any future additions of parameters since they are already bundled together seamlessly.

Answer 5

Answer №3

To achieve this functionality, utilize the @Input() decorator within your child components.

Link to example

Parent Component:

import {Component} from '@angular/core';
import {ChildComponent} from './child.component';

@Component({
  selector: 'my-parent',
  directives: [ChildComponent],
  template: `
    <div>
      <h2>I am the parent.</h2>
      My name is {{firstName}} {{lastName}}.

        <my-child firstName="{{firstName}}" 
                  lastName="{{lastName}}">

        </my-child>

    </div>
  `
})
export class ParentComponent {
  public firstName:string;
  public lastName: string;
  constructor() {
    this.firstName = 'Alice';
    this.lastName = 'Johnson';
  }
}

Child Component:

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

@Component({
  selector: 'my-child',
  template: `
    <div>
      <h3>I am the child.</h3>
      My name is {{firstName}} {{lastName}} Jr.
      <br/>
     The name I received from my parent is: {{firstName}} {{lastName}}

    </div>
  `
})
export class ChildComponent {
  @Input() firstName: string;
  @Input() lastName: string;
}

App Component:

//our root app component
import {Component} from '@angular/core';
import {ParentComponent} from './parent.component';

@Component({
  selector: 'my-app',
  directives: [ParentComponent],
  template: `
    <div>
      <my-parent></my-parent>
    </div>
  `
})
export class App {

  constructor() {
  }
}

Answer 6

To achieve this functionality, utilize the @Input() decorator within your child components.

Link to example

Parent Component:

import {Component} from '@angular/core';
import {ChildComponent} from './child.component';

@Component({
  selector: 'my-parent',
  directives: [ChildComponent],
  template: `
    <div>
      <h2>I am the parent.</h2>
      My name is {{firstName}} {{lastName}}.

        <my-child firstName="{{firstName}}" 
                  lastName="{{lastName}}">

        </my-child>

    </div>
  `
})
export class ParentComponent {
  public firstName:string;
  public lastName: string;
  constructor() {
    this.firstName = 'Alice';
    this.lastName = 'Johnson';
  }
}

Child Component:

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

@Component({
  selector: 'my-child',
  template: `
    <div>
      <h3>I am the child.</h3>
      My name is {{firstName}} {{lastName}} Jr.
      <br/>
     The name I received from my parent is: {{firstName}} {{lastName}}

    </div>
  `
})
export class ChildComponent {
  @Input() firstName: string;
  @Input() lastName: string;
}

App Component:

//our root app component
import {Component} from '@angular/core';
import {ParentComponent} from './parent.component';

@Component({
  selector: 'my-app',
  directives: [ParentComponent],
  template: `
    <div>
      <my-parent></my-parent>
    </div>
  `
})
export class App {

  constructor() {
  }
}

Sending data to child component in Angular 2

Answer №1

Answer №2

Answer №3

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