Cast int to enum strings in Typescript

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

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最佳答案

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

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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"

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I think with

\{\{message.type}}

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

\{\{TYPE[message.type]}}

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This is how enum works in the typescript:

   enum PrintMedia {
Newspaper = 1,
Newsletter,
Magazine,
Book
}


PrintMedia.Magazine;            // returns  3
PrintMedia["Magazine"];         // returns  3
PrintMedia[3];                  // returns  Magazine
PrintMedia[PrintMedia.Magazine];// returns  Magazine