Guide to implementing an enum in an Angular Component

Question

Guide to implementing an enum in an Angular Component

Having a global state (or "mode") in my Angular Components is leading me to look for more efficient ways to code. Here is what I have tried:

@Component({
      ....
})
export class AbcComponent implements OnInit {

  enum State {
    init, view, edit, create, wait
  }
  state: State = State.init;

The concept here is that functions within AbcComponent can control the template's operations by simply setting the state property. For example:

<div class="col" *ngIf="state === State.view"> ... </div>

The issue arises when trying to define the enum inside the class structure, as it is not possible. Moving it outside means the template lacks access due to scope limitations.

Any suggestions on alternative methods to achieve this?

P.S. As a side note, I've experimented with using separate boolean properties for each state, such as modeInit, modeView, etc. It works but becomes cumbersome since only one should be set to true at any given time.

angular typescript

Answer 1

Answer №1

To define the State enum outside of a class, you can store it in a separate file:

export enum State {
  initial, 
  display, 
  modify, 
  add, 
  wait
}

Then, you can assign this enum to a public field within a class:

import { State } from "../models/app-enums.model";

@Component({
  ....
})
export class AbcComponent implements OnInit {
  public StateEnum = State;
  public state = State.initial;
  ...
}

This public field can now be used to reference the enum within the template code:

<div class="col" *ngIf="state === StateEnum.display"> ... </div>

Answer 2

To define the State enum outside of a class, you can store it in a separate file:

export enum State {
  initial, 
  display, 
  modify, 
  add, 
  wait
}

Then, you can assign this enum to a public field within a class:

import { State } from "../models/app-enums.model";

@Component({
  ....
})
export class AbcComponent implements OnInit {
  public StateEnum = State;
  public state = State.initial;
  ...
}

This public field can now be used to reference the enum within the template code:

<div class="col" *ngIf="state === StateEnum.display"> ... </div>

Answer 3

Answer №2

To compare the current state value with an imported enum, you can define a method or getter within your component. Here is an example:

import { State } from "../models/state-enum.ts";

@Component({
  ....
})
export class AbcComponent implements OnInit {
  private state: State = State.init;
  
  get isView() {
    return this.state === State.view;
  }
}

template.html

<div *ngIf="isView">Oh is view!</div>

Answer 4

To compare the current state value with an imported enum, you can define a method or getter within your component. Here is an example:

import { State } from "../models/state-enum.ts";

@Component({
  ....
})
export class AbcComponent implements OnInit {
  private state: State = State.init;
  
  get isView() {
    return this.state === State.view;
  }
}

template.html

<div *ngIf="isView">Oh is view!</div>

Answer 5

Answer №3

To incorporate the enum as a static member of the component, declaration merging can also be utilized.

@Component({
    ....
})
export class AbcComponent implements OnInit {
    state = AbcComponent.State.init;
}

export namespace AbcComponent {
    export enum State {
        init, view, edit, create, wait
    }
}

Subsequently, you can access it in the template through the constructor field

<div class="col" *ngIf="state === constructor.State.view"> ... </div>

Answer 6

To incorporate the enum as a static member of the component, declaration merging can also be utilized.

@Component({
    ....
})
export class AbcComponent implements OnInit {
    state = AbcComponent.State.init;
}

export namespace AbcComponent {
    export enum State {
        init, view, edit, create, wait
    }
}

Subsequently, you can access it in the template through the constructor field

<div class="col" *ngIf="state === constructor.State.view"> ... </div>

Guide to implementing an enum in an Angular Component

Answer №1

Answer №2

Answer №3

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