在ES6/Typescript中链接承诺

Question

我需要链接promises来发出几个GET请求,并在将数据用于其他地方之前将其合并.我很难解决这两个承诺.我尝试在尝试使用之前返回两个promise的数组,.json()但这也不起作用.

activate() {

    // data is from http://jsonplaceholder.typicode.com/photos and
    // since there is not a photos2/ endpoint this is conceptual and 
    // represents batch importng
    return Promise.all([
        this.http.fetch('photos'),
        this.http.fetch('photos2')
    ]).then(responses => {

        console.log(responses); // see block of code below this for output

        // how can I combine the two promises here so I can resolve them with 'then' below?
        return responses[0].json(); // can return one response
        // return responses; //  doesn't work

    }).then(data => {
        console.log(data);
        this.photos = data;

    }).catch(err => {
        console.log(err);
    });
}

console.log的输出(响应); :

[Response, Response]
0: Response
body: (...) // readablebytestream
bodyUsed : false
headers : Headers
ok : true
status : 200
statusText : "OK"
type : "cors"
url : "http://jsonplaceholder.typicode.com/photos"
__proto__ : Object
1 : Response
 ....etc

谢谢!

Answer 1

你似乎在寻找

return Promise.all([responses[0].json(), responses[1].json()]);

或者只是做

this.photos = Promise.all([
    this.http.fetch('photos').then(response => response.json()),
    this.http.fetch('photos2').then(response => response.json())
])