如何导入枚举

Question

I have created an enum, but I am having trouble importing and using the enum in VS15.

This is the enum which is contained in enums.ts:

enum EntityStatus {
     New = 0,
     Active = 1,
     Archived = 2,
     Trashed = 3,
     Deleted = 4
}

Visual Studio sees this enum without even importing and so does not give a compile time error. But at runtime, an error is thrown

 Cannot read property 'Archived' of undefined.

So now I try to import it like I import other classes:

 import {EntityStatus} from "../../core/enums";

Visual Studio now gives a compile time error:

 "...enums is not a module ..."

So how do I import the enum?

Answer 1

I was missing the export keyword:

 export enum EntityStatus {
      New = 0,
      Active = 1,
      Archived = 2,
      Trashed = 3,
      Deleted = 4
 }

Then it worked as expected.

Answer 2

You will get the same Cannot read property 'Foo' of undefined. runtime error when you happen to define your Enum in one of the TypeScript Declaration files ( *.d.ts ) as these files does not get transpired into JavaScript.

More details with a sample app can be found here .

Answer 3

Kindly try this. It works for me

enums.ts

export enum  Category {Cricket,Tennis,Golf,Badminton}

and in required .ts file import like the way given below:

import {Category} from './enums'

Answer 4

Just ran across something similar. In my case, I had to ensure the exported enum name was different than the name of the file.

ie.

export enum AccessMode in file access-mode.ts would fail. export enum AccessMode in file access-modes.ts would work.

Answer 5

As @Sachin Kalia said, I had a problem with imports.

I have changed this:

import {MessageAction, MessageDTO} from '../../../generated/dto';

to this:

import {MessageDTO} from '../../../generated/dto';
import {MessageAction} from '../../../generated/dto'

MessageAction is my enum.

Answer 6

Encountered similar issue. For me removing the name Enum worked.

Before :

 export enum ContentStatusEnum { New = 0, Saved = 1, Ready = 2, Sent = 3, Cancel = 4, OnError = 5 }

After:

 export enum ContentStatus { New = 0, Saved = 1, Ready = 2, Sent = 3, Cancel = 4, OnError = 5 }