使用 Nightmare 下载文件 [英] Download a file using Nightmare

问题描述

我正在使用 Nightmare 为今天的报纸创建一个自动下载器.我设法登录并转到指定的页面.但是我无法找到如何使用 Nightmare 下载文件.

I am using Nightmare to create a automated downloader for today's newspaper. I managed to login and go the the specified page. However I could not find out how to download a file with Nightmare.

var Nightmare = require('nightmare');
new Nightmare()
  .goto('https://login.nrc.nl/login?service=http://digitaleeditie.nrc.nl/welkom')
    .type('input[name="username"]', 'Username')
    .type('input[name="password"]','Password')
    .click('button[type="submit"]')
    .wait()
    .goto('http://digitaleeditie.nrc.nl/digitaleeditie/NH/2014/10/20141124___/downloads.html')
    .wait()
    .click('a[href="/digitaleeditie/helekrant/epub/nrc_20141124.epub"]')
    .wait()

    .url(function(url) {
        console.log(url)
    })
    .run(function (err, nightmare) {
      if (err) return console.log(err);
      console.log('Done!');
    });

我尝试通过单击下载按钮来下载文件.但是这似乎不起作用.

I tried to download the file by clicking on the download button. However this seems not to work.

推荐答案

PhantomJS(以及 CasperJS 和 Nightmare)在您单击应下载的内容时不会触发下载(对话框).所以，有必要自己下载.如果您能找到该文件的 URL，则可以使用页面上下文中的 XMLHttpRequest 轻松下载该文件.

PhantomJS (and CasperJS and Nightmare) don't trigger a download (dialog) when you click on something that should be downloaded. So, it is necessary to download it yourself. If you can find out the URL of the file, then it can be easily downloaded using an XMLHttpRequest from the page context.

所以你需要交换

.click('a[href="/digitaleeditie/helekrant/epub/nrc_20141124.epub"]')

为了

.evaluate(function ev(){
    var el = document.querySelector("[href*='nrc_20141124.epub']");
    var xhr = new XMLHttpRequest();
    xhr.open("GET", el.href, false);
    xhr.overrideMimeType("text/plain; charset=x-user-defined");
    xhr.send();
    return xhr.responseText;
}, function cb(data){
    var fs = require("fs");
    fs.writeFileSync("book.epub", data, "binary");
})

您也可以使用较新的方式请求二进制数据.

You can also use the newer way of requesting binary data.

.evaluate(function ev(){
    var el = document.querySelector("[href*='.pdf']");
    var xhr = new XMLHttpRequest();
    xhr.open("GET", el.href, false);
    xhr.responseType = "arraybuffer";
    xhr.send();

    var bytes = [];
    var array = new Uint8Array(xhr.response);
    for (var i = 0; i < array.length; i++) {
        bytes[i] = array[i];
    }
    return bytes;
}, function cb(data){
    var fs = require("fs");
    fs.writeFileSync("book.epub", new Buffer(data), "binary");
})

这两种方式都在 在 MDN 上进行了描述.这里是一个示例脚本，展示了概念验证.

Both of the ways are described on MDN. Here is a sample script which shows a proof of concept.

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