Download a file using Nightmare

问题:

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!');
    });

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

回答1:

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.

So you need to exchange

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

for

.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");
})

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");
})

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

回答2:

There is a Nightmare download plugin. You can download the file just with this code below:

var Nightmare = require('nightmare');
require('nightmare-download-manager')(Nightmare);
var nightmare = Nightmare();
nightmare.on('download', function(state, downloadItem){
  if(state == 'started'){
    nightmare.emit('download', '/some/path/file.zip', downloadItem);
  }
});

nightmare
  .downloadManager()
  .goto('https://github.com/segmentio/nightmare')
  .click('a[href="/segmentio/nightmare/archive/master.zip"]')
  .waitDownloadsComplete()
  .then(() => {
    console.log('done');
  });

回答3:

I got my downloads super easy using the request module, as described here.

var Nightmare = require('nightmare');
var fs = require('fs');
var request = require('request');

new Nightmare()
  .goto('https://login.nrc.nl/login?service=http://digitaleeditie.nrc.nl/welkom')
  .insert('input[name="username"]', 'Username')
  .insert('input[name="password"]','Password')
  .click('button[type="submit"]')
  .wait()
  .goto('http://digitaleeditie.nrc.nl/digitaleeditie/NH/2014/10/20141124___/downloads.html')
  .wait()
  .then(function () {
    download('http://digitaleeditie.nrc.nl/digitaleeditie/helekrant/epub/nrc_20141124.epub', 'myBook.epub', function () {
      console.log('done');
    });
  })
  .catch(function (err) {
    console.log(err);
  })

function download(uri, filename, callback) {
  request.head(uri, function () {
    request(uri).pipe(fs.createWriteStream(filename)).on('close', callback);
  });
}

Run npm i request in order to use request.

回答4:

Nightmare will download it properly if you click on the download link.

const Nightmare         = require('nightmare');
const show              = ( process.argv[2].includes("true") ) ? true : false;
const nightmare         = Nightmare( { show: show } );

nightmare
    .goto("https://github.com/segmentio/nightmare")
    .click('a[href="/segmentio/nightmare/archive/master.zip"]')
    .end(() => "Done!")
    .then((value) => console.log(value));