How to download file with puppeteer using headless: true?

问题

I've been running the following code in order to download a csv file from the website http://niftyindices.com/resources/holiday-calendar:

const puppeteer = require('puppeteer');

(async () => {
const browser = await puppeteer.launch({headless: true});
const page = await browser.newPage();

await page.goto('http://niftyindices.com/resources/holiday-calendar');
await page._client.send('Page.setDownloadBehavior', {behavior: 'allow', 
downloadPath: '/tmp'})
await page.click('#exportholidaycalender');
await page.waitFor(5000);
await browser.close();
})();

with headless: false it works, it downloads the file into /Users/user/Downloads. with headless: true it does NOT work.

I'm running this on a macOS Sierra (MacBook Pro) using puppeteer version 1.1.1 which pulls Chromium version 66.0.3347.0 into .local-chromium/ directory and used npm init and npm i --save puppeteer to set it up.

Any idea whats wrong?

Thanks in advance for your time and help,

回答1:

This page downloads a csv by creating a comma delimited string and forcing the browser to download it by setting the data type like so

let uri = "data:text/csv;charset=utf-8," + encodeURIComponent(content);
window.open(uri, "Some CSV");

This on chrome opens a new tab.

You can tap into this event and physically download the contents into a file. Not sure if this is the best way but works well.

const browser = await puppeteer.launch({
  headless: true
});
browser.on('targetcreated', async (target) => {
    let s = target.url();
    //the test opens an about:blank to start - ignore this
    if (s == 'about:blank') {
        return;
    }
    //unencode the characters after removing the content type
    s = s.replace("data:text/csv;charset=utf-8,", "");
    //clean up string by unencoding the %xx
    ...
    fs.writeFile("/tmp/download.csv", s, function(err) {
        if(err) {
            console.log(err);
            return;
        }
        console.log("The file was saved!");
    }); 
});

const page = await browser.newPage();
.. open link ...
.. click on download link ..

回答2:

The problem is that the browser closes before download finished.

You can get the filesize and the name of the file from the response, and then use a watch script to check filesize from downloaded file, in order to close the browser.

This is an example:

const filename = <set this with some regex in response>;
const dir = <watch folder or file>;

// Download and wait for download
    await Promise.all([
        page.click('#DownloadFile'),
       // Event on all responses
        page.on('response', response => {
            // If response has a file on it
            if (response._headers['content-disposition'] === `attachment;filename=${filename}`) {
               // Get the size
                console.log('Size del header: ', response._headers['content-length']);
                // Watch event on download folder or file
                 fs.watchFile(dir, function (curr, prev) {
                   // If current size eq to size from response then close
                    if (parseInt(curr.size) === parseInt(response._headers['content-length'])) {
                        browser.close();
                        this.close();
                    }
                });
            }
        })
    ]);

Even that the way of searching in response can be improved though I hope you'll find this usefull.

回答3:

I spent hours poring through this thread and Stack Overflow yesterday, trying to figure out how to get Puppeteer to download a csv file by clicking a download link in headless mode in an authenticated session. The accepted answer here didn't work in my case because the download does not trigger targetcreated, and the next answer, for whatever reason, did not retain the authenticated session. This article saved the day. In short, fetch. Hopefully this helps someone else out.

const res = await this.page.evaluate(() =>
{
    return fetch('https://example.com/path/to/file.csv', {
        method: 'GET',
        credentials: 'include'
    }).then(r => r.text());
});

回答4:

I needed to download a file from behind a login, which was being handled by Puppeteer. targetcreated was not being triggered. In the end I downloaded with request, after copying the cookies over from the Puppeteer instance.

In this case, I'm streaming the file through, but you could just as easily save it.

    res.writeHead(200, {
        "Content-Type": 'application/octet-stream',
        "Content-Disposition": `attachment; filename=secretfile.jpg`
    });
    let cookies = await page.cookies();
    let jar = request.jar();
    for (let cookie of cookies) {
        jar.setCookie(`${cookie.name}=${cookie.value}`, "http://secretsite.com");
    }
    try {
        var response = await request({ url: "http://secretsite.com/secretfile.jpg", jar }).pipe(res);
    } catch(err) {
        console.trace(err);
        return res.send({ status: "error", message: err });
    }

回答5:

I have another solution to this problem, since none of the answers here worked for me.

I needed to log into a website, and download some .csv reports. Headed was fine, headless failed no matter what I tried. Looking at the Network errors, the download is aborted, but I couldn't (quickly) determine why.

So, I intercepted the requests and used node-fetch to make the request outside of puppeteer. This required copying the fetch options, body, headers and adding in the access cookie.

Good luck.

来源：https://stackoverflow.com/questions/49245080/how-to-download-file-with-puppeteer-using-headless-true

标签

node.js

chromium

Puppeteer