AXIOS：如何同时运行http请求并在请求失败时获取所有请求事件的结果

Question

我正在尝试让服务器同时获取请求，为此我编写了以下函数。

问题

如果单个呼叫失败，那么我无法获得其余请求的响应。

export const getAll = async (collection) => {
    return new Promise((resolve, reject) => {
        const requests = collection.map(req => {
            const config = {
                headers: req.headers,
                params: req.params
            }
            return axios.get(req.url, config);
        })

        axios.all(requests)
            .then(axios.spread((...args) => {
                // all succerss
                resolve(args);
            }))
            .catch(function (error) {
                // single call fails and all calls are lost
                reject(error)
            });
    })
}

无论失败还是成功，是否可以获得所有请求的结果？

Answer 1

换句话说，即使请求失败，您也希望像请求成功一样执行其余代码。

假设响应不能是null。然后我们捕获请求的错误并在这种情况下返回 null 用于请求。

export const getAll = async (collection) => {
    const requests = collection.map(req => {
        const config = {
            headers: req.headers,
            params: req.params
        };
        return axios.get(req.url, config).catch(() => null);
    })
    return axios.all(requests);
}

所以如果你有 catch() 并且它没有抛出异常，那么所有以后的代码都会像 Promise 一样被解决而不是被拒绝。

还请注意，您不需要从 async 函数显式返回 Promise，因为它会自动发生。更重要的是：由于函数内部没有await，因此实际上不需要将其标记为async。最后axios.all 返回Promise 所以你不需要手动resolve/reject Promise。

Answer 2

我过去这样做的方法是将我的 promise 的返回值包装到一个具有 result 字段或类似字段和 err 字段的对象中：

export const getAll = async (collection) => {
    const requests = collection.map(req => {
        const config = {
            headers: req.headers,
            params: req.params
        }

        return axios.get(req.url, config)
            //wrap all responses into objects and always resolve
            .then(
                (response) => ({ response }),
                (err) => ({ err })
            );
    });

    return axios.all(requests)
        //note that .then(axios.spread((...args) => {}) is the same as not using
        //spread at all: .then((args) => {})
        .then(axios.spread((...args) => {
            //getAll will resolve with a value of
            //[{ response: {}, err: null }, ...]

            return args;
        }))
        .catch((err) => {
            //this won't be executed unless there's an error in your axios.all
            //.then block

            throw err;
        });
}

另请参阅 @skyboyer 的帖子，了解他对您的其余代码提出的一些要点。

Answer 3

这是基于 Andrew 解决方案的完整的基于节点 js 的示例：

const axios = require('axios');

const getAll = async (collection) => {
    const requests = collection.map(req => {
        const config = {
            // headers: req.headers,
            params: req.params
        }

        return axios.get(req.url, config)
        //wrap all responses into objects and always resolve
            .then(
                (apiResponse) => ({
                    apiResponse
                }),
                (apiError) => ({
                    apiError
                })
            );
    });

    return axios.all(requests)
    //note that .then(axios.spread((...args) => {}) is the same as not using
    //spread at all: .then((args) => {})
        .then(axios.spread((...args) => {
            //getAll will resolve with a value of
            //[{ response: {}, err: null }, ...]

            return args;
        }))
        .catch((axiosError) => {
            //this won't be executed unless there's an error in your axios.all
            //.then block

            throw axiosError;
        });
}

let api1 = {url: "http://localhost:3000/test?id=1001", param: ""};
let api2 = {url: "http://localhost:3000/test?id=1002", param: ""};
let api3 = {url: "http://localhost:3000/test?id=1003", param: ""};
let apis = [api1, api2, api3];

getAll(apis).then((res) => {
        console.log("getAll call finished");
        //console.log(res);
    }
);