获取api - 在两者中获取json body并捕获块以获取单独的状态代码

Question

我使用fetch api来获取可能返回的URL:

回复:状态= 200,json body = {'user':'abc','id':1}

要么

回复:状态= 400,json body = {'reason':'某些原因'}

要么

回复:状态= 400,json body = {'reason':'其他原因'}

我想创建一个单独的函数request(),我从代码的各个部分使用如下:

    request('http://api.example.com/').then(
        // status 200 comes here
        data => // do something with data.id, data.user
    ).catch(
        // status 400, 500 comes here
        error =>  // here error.reason will give me further info, i also want to know whether status was 400 or 500 etc
    )

我无法进行200到400,500之间的分割(我试过抛出一个错误).当我抛出错误时,我发现很难仍然提取JSON主体(用于error.reason).

我目前的代码如下:

import 'whatwg-fetch';

/**
 * Requests a URL, returning a promise
 */
export default function request(url, options={}) {

    console.log('sending api request, url = ' + url)

    return fetch(url, options)
        .then(checkStatus)
        .then(parseJSON)
        .then((data) => ({data}))
        .catch((err) => ({err}));
}


function checkStatus(response) {
    if (response.status >= 200 && response.status < 300) {
        return response;
    }

    const error = new Error(response.statusText);
    error.response = response;
    throw error;
}



function parseJSON(response) {
    return response.json();   // json() is a promise itself
}

我试图通过如下操作来解决这个问题,通过反转.then()调用的顺序,但是不起作用

export default function request(url, options) {
    return fetch(url, options)
        .then(parseJSON)        // note that now first calling parseJSON to get not just JSON but also status. 
        .then(checkStatus)      // i.e. Inverted order of the two functions from before

        .then((data) => ({data}))
        .catch((err) => ({err}));
}

function checkStatus({data, status}) {

    if (status >= 200 && status < 300) {
        return data;
    }
    else {
        // const error = new Error(response.statusText);
        const error = new Error("Something went wrong");
        // error.response = response;
        error.data = data;

        throw error;
    }

}

function parseJSON(response) {
    let jsonBody

    response.json().then(json => {
        jsonBody = json                 // this does not help, i thought it will make jsonBody fill up, but seems its in a diff thread
    })              

    return {
        data: jsonBody,
        status: response.status     // my aim is to send a whole dict with status and data to send it to checkStatus, but this does not work
    }
}

Answer 1

response.json()返回异步结果.你没有parseJSON从.then()链接中返回对象response.json().要纠正这个问题,你可以返回response.json()在承诺parseJSON的呼叫和包含返回的对象data,并status从内部.then()链接到response.json()

function parseJSON(response) {
    return response.json().then(json => {
          return {
                   data: json,
                   status: response.status  
                 }
    })         
}