问题描述
当试图在App组件（组件，我们自举）一切正常发现使用 HTTP ：
When trying to use Http in the App component (the component we are bootstrapping) everything works find:
export default class AppComponent {
constructor(public http: Http){
console.log(this.http);
}
getData() {
}
}
bootstrap(AppComponent, [HTTP_PROVIDERS]);
但是，如果我换的Http以 CustomHttpService （和ofcouse添加到CustomHttpService引导其它的组件阵列）：
But if I wrap Http with a CustomHttpService (and ofcouse add CustomHttpService to the bootstrap componenets array):
自定义HTTP-service.ts：
export default class CustomHttpService {
constructor(public http: Http){
console.log(this.http);
}
getData() {
}
}
app.ts
bootstrap(AppComponent, [CustomehttpService]);
我收到：
NoAnnotationError {message: "Cannot resolve all parameters for CustomHttpServic…ake sure they all have valid type or annotations.", stack: $
## _onError ##
TypeError: Cannot read property 'get' of undefined
at angular2.dev.js:19620
at Zone.run (angular2.dev.js:138)
at Zone.run (angular2.dev.js:10644)
at NgZone.run (angular2.dev.js:10607)
at ApplicationRef_.bootstrap (angular2.dev.js:19615)
at Object.commonBootstrap (angular2.dev.js:26650)
at Object.bootstrap (angular2.dev.js:27475)
at Object.<anonymous> (app.ts:23)
at app.ts:23
at SystemJSLoader.__exec (system.src.js:1384)
Uncaught TypeError: Cannot read property 'get' of undefined
我在想什么？难道这还不够导入模块和注册自定义服务的引导作用？
What am I missing? Isn't that enough to import modules and register the custom service in the bootstrap function?
此问题是适用于每一个有没有元数据类（组件，浏览等），我们要注入到我们的应用程序。
This question is relevant to every class that has no metadata (Component, View etc.. ) we want to inject to our application.
推荐答案
感谢埃里克·马丁内斯评论和this真棒解释我看得出来，在没有元数据附加到类（装饰）的打字稿类型是不够的。
Thanks to Eric Martinez comment and this awesome explanation I could see that the typescript types are not enough when no meta-data is attached to the class (with decorators).
在这篇文章中提出的解决方法是元数据添加到我们要注入的类（在此我的情况是 CustomHttpService ），这将成为：
The fix proposed in this article is to add metadata to the class we want to inject (in my case this is the CustomHttpService) and this will become:
@Injectable() // from angluar2/core
export default class CustomHttpService {
constructor(public http: Http){
console.log(this.http);
}
getData() {
}
}
和当然的服务添加到自举功能的注射数组：
and of course to add the service to the injectables array in the bootstrap function:
bootstrap(AppComponent, [HTTP_PROVIDERS, CustomHttpService]);
和现在的作品。
这篇关于Angular2：如何注入一个没有装饰的应用服务？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！