Angular2将响应JSON转换为Typescript枚举

Question

In Angular2 I receive data from the server as a JSON object. One of the fields is a resource type. Which can be an image, video or audio. The enum looks like:

export enum MediaType {
  image,
  video,
  audio
}

However when I try to cast the response to an MediaType enum:

this.type = MediaType[data["type"]];

I got an error:

error TS2322: Type 'string' is not assignable to type 'MediaType'.

Any thoughts?

Answer 1

Is data['type'] part of the JSON response, containing a MediaType? If so it can be cast like this:

this.type = <MediaType> data["type"];

Answer 2

Your data["type"] should be number, either 0, 1 or 2...

Consider this:

enum MediaType {
 image,
 video,
 audio
}
let type: MediaType;
type = MediaType[0] // image
type = MediaType[1] // video
type = MediaType[2] // audio