How to download pdf from puppeteer using Nest js as Server Side and React in Client Side?

Question

I am using Nest in backend to generate a pdf file with Puppeteer. Puppeteer is working fine when I give it the path to create pdf on disk.

I am currently returning the pdf.

This is the code generating the pdf:

const browser = await puppeteer.launch({ headless: true });
    const page = await browser.newPage();
    await page.goto('https://blog.risingstack.com', {waitUntil: 'networkidle0'});


    var options = {
      width: '1230px',
      displayHeaderFooter: false,
      margin: {
        top: "10px",
        bottom: "30px"
      },
      printBackground: true,
    }

    const pdf = await page.pdf(options);
  
    await browser.close();
    return pdf

And this is the controller that calls the previous function:

  @Header('Content-Type', 'application/pdf')
  async Printpdf(@Body() message: any) {
    console.log(message);
    return this.PrintpdfService.printpdf();
  }

In React I am calling this with axios like this:

return axios.post(`http://localhost:3000/printpdf`,data, {
    responseType: 'arraybuffer',
    headers: {
      'Accept': 'application/pdf'
    }
  });

I am trying to download the pdf with this:

getBuildingReport(data).then((response) => {
      console.log(response);
      const blob = new Blob([response.data], {type: 'application/pdf'})
       const link = document.createElement('a')
       link.href = window.URL.createObjectURL(blob)
       link.download = `name.pdf`
       link.click();
    })
    .catch(err => {
      console.log(err)
    }); 

I followed this tutorial. https://blog.risingstack.com/pdf-from-html-node-js-puppeteer/#option3

But the downloaded pdf is build correctly and is imposible to open it as I get "Failed to load PDF document."

Answer 1

I figured this out for a project once and saved the snippet... The key is loading the PDF into a buffer, and then sending that back to the client.

Here's an example function implemented in a NestJS service:

  async generatePDF(): Promise<Buffer> {
    const content = fs.readFileSync(
      path.resolve(__dirname, './templates/invoice.html'),
      'utf-8'
    )

    const browser = await puppeteer.launch({ headless: true })
    const page = await browser.newPage()
    await page.setContent(content)

    const buffer = await page.pdf({
      format: 'A4',
      printBackground: true,
      margin: {
        left: '0px',
        top: '0px',
        right: '0px',
        bottom: '0px'
      }
    })

    await browser.close()

    return buffer
  }

Here's an example NestJS controller:

  @Get('/:uuid/pdf')
  async getInvoicePdfByUUID(
    @Param('uuid', ParseUUIDPipe) uuid: string,
    @GetUser() user: User,
    @Res() res: Response,
  ): Promise<void> {

    // ...

    const buffer = await this.invoicesService.generatePDF()

    res.set({
      // pdf
      'Content-Type': 'application/pdf',
      'Content-Disposition': 'attachment; filename=invoice.pdf',
      'Content-Length': buffer.length,

      // prevent cache
      'Cache-Control': 'no-cache, no-store, must-revalidate',
      'Pragma': 'no-cache',
      'Expires': 0,
    })

    res.end(buffer)
  }

Note that the above assumes you're using NestJS with Express.

Cheers!