如何标记标记函数的返回类型为自定义类型

Question

我有一段代码，看起来像这样

import * as Promise from 'bluebird'; 
import {Response} from '../commonInterfaces/httpService'; 

getCall(url: string, accessToken: string, extraHeaders: object): Promise<Response> { 
    let headers = this.getHeaders(accessToken, extraHeaders); 
    return new Promise((resolve, reject) => { 
     request({ 
      url: url, 
      method: "GET", 
      withCredentials: false, 
      json: true, 
      headers: headers 
     }, (err: Error, response: Response) => { 
      if (err) { 
       reject(err) 
      } else { 
       resolve(response) 
      } 
     }); 
    }); 
} 

和响应的承诺是一个接口

interface Response {statusCode: number, body: object} 

和我收到以下错误

[ts] 
Type 'Bluebird<{}>' is not assignable to type 'Bluebird<Response>'. 
Type '{}' is not assignable to type 'Response'. 
Property 'statusCode' is missing in type '{}'. 

可能是什么问题？

Answer 1

似乎编译器不会从调用resolve(response)推断出该类型。
您可以通过自己指定一般约束来“帮助”它：

return new Promise<Response>((resolve, reject) => { ... });