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PDF Generation with Chrome Puppeteer sample

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Richard Szolár edited this page May 7, 2020 · 2 revisions

Here is a sample on how to generate a PDF from an html string with puppeteer and chrome through your Servicenow instance.

// require puppeteer, fs and request packages, these are preinstalled in your node vm already if you've used the repo
const puppeteer = require('puppeteer');
const fs = require('fs');
const request = require('request');
// async function for generating the pdf
async function printPDF() {
    // let's make a connection to the chrome headless browser, notice the IP, this is the address of the container running the browser instance
    const browser = await puppeteer.connect({
        browserURL: "http://172.20.128.4:9222",
        headless: true,
        slowMo: 250
    });
    // open a new tab
    const page = await browser.newPage();
    await page.setViewport({
        width: 1920,
        height: 1080
    });
    // get the number of the incident from our bootstrap script
    let incNum = _getData()['result'][0]['number'];
    // html contents
    const htmlContent = '<html>' +
        '<head>' +
        '<title>Some nice title</title>' +
        '</head>' +
        '<body>' +
        '<h3>This is a h3 heading for ' + incNum + '</h3>' +
        '<img src="https://images.pexels.com/photos/1130980/pexels-photo-1130980.jpeg?auto=compress&cs=tinysrgb&dpr=1&w=500" alt="picture here" />' +
        '</body>' +
        '</html>';
    // set the page's content to the html string
    await page.setContent(htmlContent);
    await page.emulateMedia("screen");
    // save the pdf locally to a temporary folder, you need to make sure that the node vm has access to the folder
    await page.pdf({
        path: "./tmp/rendered_from_html.pdf",
        format: 'A4'
    });
    // after render and save, close the page
    await page.close();
    // disconnect from the browser
    await browser.disconnect();
    // read the contents of the file into the variable
    const pdfFileData = base64_encode("./tmp/rendered_from_html.pdf");
    // use the postback function to send back the contents to the log entry table
    doPostBack(_getLogID(), {
        pdf: pdfFileData
    });
}
// function to encode file data to base64 encoded string
function base64_encode(file) {
    // read binary data, in sync mode, not ideal, but for the demo purpose it is enough
    var bitmap = fs.readFileSync(file);
    // convert binary data to base64 encoded string
    return new Buffer(bitmap).toString('base64');
}
const doPostBack = (logID, data) => {
    // use basic auth for api authentication user=rest.default & password=rest.default
    const baseUrl = "https://rest.default:rest.default@instancename.service-now.com";
    const endpoint = baseUrl + "/api/x_321937_snc_node/postback";
    request.post(endpoint, {
        json: {
            logID: logID,
            result: data
        }
    }, (error, res, body) => {
        if (error) {
            console.error(error);
            return
        }
        console.log(`statusCode: ${res.statusCode}`);
        console.log(body)
    })
};
// call the async function
printPDF();

For a full example and explanation, please visit the blog post Blog post

Servicenow x NodeJS @ 2019

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