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使用请求.getAsync从蓝鸟,如何'管道'到一个文件

bluebird promise asynchronous node.js javascript

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robe007 Leo Aguirre · 技术社区 · 8 年前

Promise.mapSeries 具有 request.getAsync 和 spread 青鸟 .

但是在 then 我要知道结果 request pipe 和 createWriteStream

request(url).pipe(fs.createWriteStream(file));

这是我使用的代码:

const Promise = require('bluebird');
const request = Promise.promisifyAll(require('request'), { multiArgs: true });
const fs = Promise.promisifyAll(require("fs"));

const urls = ['http://localhost/test-pdf/one.pdf', 'http://localhost/test-pdf/two.pdf'];

Promise.mapSeries(urls, url => {
    return request.getAsync({url: url, encoding:'binary'}).spread((response, body) => {
        if (response.statusCode == 200){
            let r = {};
            r.name = url.match(/\/([^/]*)$/)[1]; // get the last part of url (file name)
            r.content = body;
            console.log(`Getting ${r.name}`);
            return r;
        }
        else if (response.statusCode == 404){
            console.log(`The archive ${url.match(/\/([^/]*)$/)[1]} does not exists`);
        }
        else throw new Error(`Unsuccessful attempt. Code: ${response.statusCode}`);
    });
}).then((result) => {
    // Here I want to 'pipe' to a file the result from 'getAsync'
}).catch((error) =>{
    console.error(error);
})

我的问题是:

我该怎么办管将结果从 getAsync 管 功能?有可能吗?

警察局: 我知道我可以用 fs.promises ,但我只是想知道是否有可能以我发布的方式来做

1 回复 | 直到 8 年前

1

Roamer-1888 8 年前

我想答案已经在这个问题上了 .then() 似乎是 .pipe() 你在寻找。

可能缺少的是 (result) (results) {name, content} 产生于 Promise.mapSeries(urls, ...) .

Promise.mapSeries(urls, url => {
    return request.getAsync({'url':url, 'encoding':'binary'}).spread((response, body) => {
        if (response.statusCode == 200) {
            return {
                'name': url.match(/\/([^/]*)$/)[1], // get the last part of url (file name)
                'content': body
            };
        } else if (response.statusCode == 404) {
            throw new Error(`The archive ${url.match(/\/([^/]*)$/)[1]} does not exist`);
        } else {
            throw new Error(`Unsuccessful attempt. Code: ${response.statusCode}`);
        }
    });
}).then((results) => {
    // Here write each `result.content` to file.
}).catch((error) => {
    console.error(error);
});

实际上,你可能不会选择这样写,因为 getAsync() 需要在任何写入开始之前完成。

在大多数情况下(也可能是您想要的情况下),更好的流应该是来自每个成功用户的内容 getAsync() 尽快写好:

Promise.mapSeries(urls, url => {
    let name = url.match(/\/([^/]*)$/)[1]; // get the last part of url (file name)
    return request.getAsync({'url':url, 'encoding':'binary'}).spread((response, body) => {
        if (response.statusCode == 200) {
            // write `body.content` to file.
        } else if (response.statusCode == 404) {
            throw new Error(`The archive ${name} does not exist`);
        } else {
            throw new Error(`Unsuccessful attempt. Code: ${response.statusCode}`);
        }
    });
}).catch((error) => {
    console.error(error);
});

捕获单个url/获取/写入错误
编译成功/失败统计。

Promise.mapSeries(urls, url => {
    let name = url.match(/\/([^/]*)$/)[1] || ''; // get the last part of url (file name)
    if(!name) {
        throw new RangeError(`Error in input data for ${url}`);
    }
    return request.getAsync({'url':url, 'encoding':'binary'}).spread((response, body) => {
        if (response.statusCode == 200) {
            // write `body.content` to file.
            return { name, 'content': body };
        } else if (response.statusCode == 404) {
            throw new Error(`The archive ${name} does not exist`);
        } else {
            throw new Error(`Unsuccessful attempt. Code: ${response.statusCode}`);
        }
    })
    .catch(error => ({ name, error }));
}).then((results) => {
    let successes = results.filter(res => !res.error).length;
    let failures = results.filter(res => !!res.error).length;
    let total = results.length;
    console.log({ successes, failures, total }); // log success/failure stats
}).catch((error) => {
    console.error(error); // just in case some otherwise uncaught error slips through
});