Determining the parental origin of a child component

Question

Determining the parental origin of a child component

I've encountered a situation where I have a component that serves as a child to two distinct parent components. Each parent component belongs to a different class, and I need to perform specific actions based on which parent component the child is in.

Is there a way to determine this by leveraging any combination of @Host, @Inject, or instanceof? If not, are there alternative methods to achieve the desired functionality?

angular typescript inheritance angular6

Answer 1

Answer №1

In my opinion, it is best to avoid approaching the problem in this manner. If you require different behavior in the child component, consider the following options:

Utilize an @Input property that must be filled in by the parent so the child knows how to handle that value.
Alternatively, use an intermediary such as a state management library like NgRx or Akita, or a service that facilitates communication between components.

While it is technically feasible for children to be aware of their parents as you suggest, I do not recommend it.

For instance, picture a scenario where you have a calendar button used across 300 different parent components - with 150 wanting it blue and the other 150 wanting it red.

If you opt for switching based on parent conditions, you would need to include 300 conditions in your child component code.

On the other hand, if you pass an input property or utilize a shared service property, you can have more generic code to handle those sets of values, which in this case would just be 2: red and blue.

Answer 2

In my opinion, it is best to avoid approaching the problem in this manner. If you require different behavior in the child component, consider the following options:

Utilize an @Input property that must be filled in by the parent so the child knows how to handle that value.
Alternatively, use an intermediary such as a state management library like NgRx or Akita, or a service that facilitates communication between components.

While it is technically feasible for children to be aware of their parents as you suggest, I do not recommend it.

For instance, picture a scenario where you have a calendar button used across 300 different parent components - with 150 wanting it blue and the other 150 wanting it red.

If you opt for switching based on parent conditions, you would need to include 300 conditions in your child component code.

On the other hand, if you pass an input property or utilize a shared service property, you can have more generic code to handle those sets of values, which in this case would just be 2: red and blue.

Answer 3

Answer №2

Applying the principles of redux can be beneficial in this scenario. By establishing a state within a designated service, comparable to the store employed in redux, we can ensure that any changes made in one of the two parent components are promptly reflected in the state. Subsequently, the child component will have access to information regarding which parent component is currently active by referencing the state.

Answer 4

Applying the principles of redux can be beneficial in this scenario. By establishing a state within a designated service, comparable to the store employed in redux, we can ensure that any changes made in one of the two parent components are promptly reflected in the state. Subsequently, the child component will have access to information regarding which parent component is currently active by referencing the state.

Answer 5

Answer №3

If the parent components are not connected hierarchically or are siblings, a simple and type-safe approach is to create an enum for the parent types:

export enum ParentType {
  TypeA = 'Parent A',
  TypeB = 'Parent B'
}

You can then define an @Input property in your ChildComponent, like so:

import { Component, Input } from '@angular/core';
import { ParentType } from './parent-type.enum';

@Component({
  selector: 'child',
  template: `<h1>My Parent IS {{ parent }}</h1>`,
  styles: [`h1 { font-family: Lato; }`]
})
export class ChildComponent {
  @Input() parent: ParentType;
}

And use it in your parent components as follows:

For Parent Component 1:

import { Component, Input } from '@angular/core';
import { ParentType } from './parent-type.enum';

@Component({
  selector: 'parent-a',
  template: `<child [parent]="parent"></child>`,
  styles: [`h1 { font-family: Lato; }`]
})
export class ParentAComponent {
  parent = ParentType.TypeA;
}

For Parent Component 2:

import { Component, Input } from '@angular/core';
import { ParentType } from './parent-type.enum';

@Component({
  selector: 'parent-b',
  template: `<child [parent]="parent"></child>`,
  styles: [`h1 { font-family: Lato; }`]
})
export class ParentBComponent {
  parent = ParentType.TypeB;
}

Check out this Sample StackBlitz for reference.

Answer 6

If the parent components are not connected hierarchically or are siblings, a simple and type-safe approach is to create an enum for the parent types:

export enum ParentType {
  TypeA = 'Parent A',
  TypeB = 'Parent B'
}

You can then define an @Input property in your ChildComponent, like so:

import { Component, Input } from '@angular/core';
import { ParentType } from './parent-type.enum';

@Component({
  selector: 'child',
  template: `<h1>My Parent IS {{ parent }}</h1>`,
  styles: [`h1 { font-family: Lato; }`]
})
export class ChildComponent {
  @Input() parent: ParentType;
}

And use it in your parent components as follows:

For Parent Component 1:

import { Component, Input } from '@angular/core';
import { ParentType } from './parent-type.enum';

@Component({
  selector: 'parent-a',
  template: `<child [parent]="parent"></child>`,
  styles: [`h1 { font-family: Lato; }`]
})
export class ParentAComponent {
  parent = ParentType.TypeA;
}

For Parent Component 2:

import { Component, Input } from '@angular/core';
import { ParentType } from './parent-type.enum';

@Component({
  selector: 'parent-b',
  template: `<child [parent]="parent"></child>`,
  styles: [`h1 { font-family: Lato; }`]
})
export class ParentBComponent {
  parent = ParentType.TypeB;
}

Check out this Sample StackBlitz for reference.

Determining the parental origin of a child component

Answer №1

Answer №2

Answer №3

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