How to convert html to pdf using Puppetter from dotnet Core

Puppetter is a nodejs library developed by google which calls chromium on the background to do certain tasks. One of this tasks can be convert an html document/url into a pdf.
Since we want to use this feature from dotnet core C# there are a few steps that we must follow.

First we need the nutget package for NodeServices
Install-Package Microsoft.AspNetCore.NodeServices

Then we need to enable this NodeServices on our Startup.cs

	// This method gets called by the runtime. Use this method to add services to the container.
	public void ConfigureServices(IServiceCollection services)
	{
	services.Configure<CookiePolicyOptions>(options =>
	{
	// This lambda determines whether user consent for non-essential cookies is needed for a given request.
	options.CheckConsentNeeded = context => true;
	options.MinimumSameSitePolicy = SameSiteMode.None;
	});
	//Register NodeService
	services.AddNodeServices();// this is in package Microsoft.AspNetCore.NodeServices
	services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
	}

view raw Startup.cs hosted with ❤ by GitHub

Install required node packages

npm init
npm install puppetter
npm install fs-extra
npm install uuid

Create a puppetter.js file on your solution with this contents.

	module.exports = async function (callback, html, headerTemplate, footerTemplate ) {
	try {
	var puppeteer = require('puppeteer');
	var fs = require('fs-extra');
	const uuidv4 = require('uuid/v4');
	var browser = await puppeteer.launch();
	var page = await browser.newPage();
	await page.setContent(html);
	await page.emulateMedia('screen');
	var outFileName = uuidv4() + "-pdf.tmp";
	await page.pdf({
	path: outFileName,
	format: 'A4',
	printBackground: true,
	displayHeaderFooter: true,
	headerTemplate: headerTemplate,
	footerTemplate: footerTemplate,
	margin: { top: "40", bottom: "40" }
	}).then(function (resp) {
	var pdf = fs.readFileSync(outFileName);
	var array = new Uint8Array(pdf);
	//Clean file
	fs.remove(outFileName);
	callback(null, [].slice.call(array));
	});
	await browser.close();
	process.exit();
	callback(null, new Uint8Array(pdf));
	} catch (e) {
	callback(e, null);
	}
	};

view raw puppetter.js hosted with ❤ by GitHub

Now everything is set, only step required is to call the module from C#.

	[HttpGet]
	public async Task<ActionResult> Pdf([FromServices] INodeServices nodeServices)
	{
	HttpClient hc = new HttpClient();
	var htmlContent = "<h1>Super testing</h1>";
	var headerTemplate = "<div></div>";
	var footerTemplate= "<div class='footer' style='width: 100%; font-size:12px; text-align:right; color:white; background:black; -webkit-print-color-adjust:exact'><span class='pageNumber'></span>/<span class='totalPages'></span></div>";
	var result = await nodeServices.InvokeAsync<byte[]>("./puppetter", htmlContent, headerTemplate, footerTemplate );
	HttpContext.Response.ContentType = "application/pdf";
	HttpContext.Response.Headers.Add("x-filename", "report.pdf");
	HttpContext.Response.Headers.Add("Access-Control-Expose-Headers", "x-filename");
	HttpContext.Response.Body.Write(result, 0, result.Length);
	return new ContentResult();
	}

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