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Cast int to enum strings in Typescript

Posted by: admin November 16, 2021 Leave a comment

Questions:

I get from a RESTful Service the following data:

[
  {
    "id": 42,
    "type": 0,
    "name": "Piety was here",
    "description": "Bacon is tasty, tofu not, ain't nobody like me, cause i'm hot...",
  }...

And I’m mapping with this class:

export enum Type {
  Info,
  Warning,
  Error,
  Fatal,
}


export class Message{
  public id: number;
  public type: Type:
  public name: string;
  public description: string;
}

But when I access ‘type’ in Angular2 I get only a int value. But I’d like to get a string value.

e.g:

'message.type=0'
{{message.type}} => should be Info
'message.type=1'
{{message.type}} => should be Warning
Answers:

Enums in TypeScript are numbers at runtime, so message.type will be 0, 1, 2 or 3.

To get the string value, you need to pass that number into the enum as an index:

Type[0] // "Info"

So, in your example, you’ll need to do this:

Type[message.type] // "Info" when message.type is 0

Docs

###

Enums in TypeScript are objects at runtime that have properties that go from int -> string and from string -> int for all possible values.

To access the string value you will need to call:

Type[0] // "Info"

Make sure that you are passing the correct type into the property accessor though because chained calls can result in the following:

Type[Type.Info] // "Info"
Type[Type[Type.Info]] // 0
Type["Info"] // 0
Type[0] // "Info"

###

I think with

{{message.type}}

you just get the mapped value and not the enum.
Please try following code.

{{TYPE[message.type]}}