Angular 2 服务错误。找不到原因

Question

我是 Angular 的新手，现在已经被困了一段时间。我正在尝试提供一个从内部 webapi 获取数据的服务，它以前工作但现在它给出了一个我无法解决的错误。希望你们中的一个能帮助我...服务:

import {Injectable} from "@angular/core";
import {Http} from '@angular/http';

import 'rxjs/add/operator/toPromise';

import {GraphData} from './graph-data';

@Injectable
export class GraphDataService {
    private dataApiUrl = 'app/graph-data';

    constructor(private http: Http) {}

    getGraphData() : Promise<GraphData[]> {
        return this.http.get(this.dataApiUrl)
            .toPromise()
            .then(response => response.json().data as GraphData[])
            .catch(this.handleError);
    }

    private handleError(error: any): Promise<any> {
        console.error('an error occurred', error); // only for demo
        return Promise.reject(error.message || error);
    }
}

编译js报错:

app/graph-data.service.ts(11,1): error TS1238: Unable to resolve signature of class decorator when called as an expression.
  Supplied parameters do not match any signature of call target.

Answer 1

你的装饰器应该是这样的:

@Injectable()

括号是必需的