如何使用 ecmascript-6 获取自定义服务器端错误消息并获取 api? [英] How to get custom server-side error message with ecmascript-6 and fetch api?

问题描述

当客户端获取请求导致服务器端出现错误时，我想返回错误代码 (400) 和自定义消息.我不知道如何在客户端优雅地使用 fetch 和 Promise 检索两者.

When a client-side fetch request results in an error on the server side, I'd like to return an error code (400) and a custom message. I don't know how to retrieve both on the client-side elegantly using fetch and promises.

return fetch('/api/something')
    .then(response => response.json())
    .then(json => {
         console.log(json.message)
        // I only have access to the json here.
        // I'd also like to get the response status code 
        // (from the response object) and potentially 
        // throw an error complete with the custom message.
    })
    .catch(function(ex) {
        console.log('Unhandled Error! ', ex);
    });

谢谢！

推荐答案

您只能访问 JSON 字符串，因为这是您在第一个 中的 onFulfill 回调中返回的内容.then().更好的方法是返回一个 Promise.all() 包装器，该包装器解析为具有原始响应对象以及已解析"JSON 对象的数组:

You only have access to the JSON string since that is what you returned from the onFulfill callback in your first .then(). A better approach would be to return a Promise.all() wrapper that resolves to an array with the original response object as well as the "resolved" JSON object:

return fetch('/api/something')
    .then(response => Promise.all([response, response.json()]))
    .then(([response, json]) => {
        if (response.status < 200 || response.status >= 300) {
            var error = new Error(json.message);
            error.response = response;
            throw error;
        }
        // Either continue "successful" processing:
        console.log('success!', json.message);
        // or return the message to seperate the processing for a followup .then()
        // return json.message;
    })
    .catch(function(ex) {
        console.log('Unhandled Error! ', ex);
    });

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