typescript 无法在 angular 2 模块中导出接口？
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An interface cannot be exported in an angular 2 module?
提问by Myonara
I tried to export an interface in a NgModule-declaration and export and getting this error already in the editor (Visual Studio Code): [ts] 'MyInterface' only refers to a type, but is being used as a value here.
我试图在 NgModule 声明中导出一个接口并导出并在编辑器（Visual Studio Code）中已经得到这个错误： [ts] 'MyInterface' only refers to a type, but is being used as a value here.
Here is the example code Edit-1:
这是示例代码Edit-1：
import { NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';
import { FormsModule } from '@angular/forms';
import { MaterialModule } from '@angular/material';
import { MyInterface } from './my.interface';
import { MyService } from './my.service';
@NgModule({
imports: [ CommonModule, FormsModule, MaterialModule.forRoot() ],
declarations: [ MyInterface],//<- this is causing the message
exports: [ MyInterface],
providers: [ MyService ]
})
export class MyModule { }
One part of an explanation I found in the answer to this post: "since interfaces are erased at runtime in TypeScript". I'm currently refactoring my app to feature modules, so I cannot test it right now: Can I use the interfaces only by import from './mypathto/my.interface'?
我在这篇文章的答案中找到的解释的一部分：“因为接口在 TypeScript 中在运行时被擦除”。我目前正在重构我的应用程序以使用功能模块，因此我现在无法对其进行测试：我可以仅通过从 './mypathto/my.interface' 导入来使用这些接口吗？
回答by Poul Kruijt
You cannot export an interface. You can only export:
您不能导出接口。您只能导出：
- Other modules
- Components
- Directives
- Pipes
- 其他模块
- 组件
- 指令
- 管道
NgModuleis an angular concept and should not be confused with a typescript module. To make a third party, who uses your module, able to use your interface, you should create a .d.tsdefinition file with your module.
NgModule是一个角度概念，不应与打字稿模块混淆。为了让使用你的模块的第三方能够使用你的界面，你应该.d.ts用你的模块创建一个定义文件。
If you want to use a interface inside another NgModule of yours, you should just use:
如果你想在你的另一个 NgModule 中使用一个接口，你应该使用：
import {InterfaceName} from 'path/to/ngmodule/to/interface';
Also, do not put an interface in the declarations array, this is only used for pipes/components/directives.
此外，不要在声明数组中放置接口，这仅用于管道/组件/指令。
If you want your interface to be usable outside of an library, you should add it to the export of your index.ts:
如果您希望您的界面在库之外可用，您应该将其添加到您的导出中index.ts：
export {InterfaceName} from 'path/to/ngmodule/to/interface';
回答by trojan
Well actually you can export an interface, but not the way you are trying to do.
好吧，实际上您可以导出接口，但不能以您尝试的方式导出。
First generate interfaces.ts file by typing
首先通过键入生成 interfaces.ts 文件
ng g interface <interface_name>
ng g interface <interface_name>
Example of interface file:
接口文件示例：
export interface Auction{ $key?:string; $auctioneer:string; ... }
export interface Item{ $key?:string; condition?:string; description?:string; ...}
export interface Bid{ $key?:string; amount:number; auction:string; ...}
After modifying the file to your needs you can import just one, all or chosen interfaces like this:
根据您的需要修改文件后，您可以只导入一个、所有或选定的接口，如下所示：
import { Auction } from './interfaces';
or
或者
import * as interfaces from './interfaces';
// then you have to call interfaces.Auction
If per chance you know how to share interfaces globally pls. let me know here: Angular how to share interfaces across the app
如果有机会您知道如何全局共享接口。让我知道：Angular 如何在应用程序中共享界面
