如何解决此PDF生成问题？

Question

Employee moved on and left me with this code that was once working to generate PDFs. I haven't had any luck trying to debug - with breakpoints or even console.logs - the script listed here at the bottom; is there a way to search the huge list of loaded scripts in Visual Studio?

C# error:

{System.Net.Http.HttpRequestException: An error occurred while sending the request. ---> System.IO.IOException: The server returned an invalid or unrecognized response.
   at System.Net.Http.HttpConnection.FillAsync()

Client Side error: (is this because the server never returns anything?)

ERROR Error: Uncaught (in promise): DataCloneError: Failed to execute 'postMessage' on 'Worker': TypeError: Failed to fetch could not be cloned.
Error: Failed to execute 'postMessage' on 'Worker': TypeError: Failed to fetch could not be cloned.
    at MessageHandler.postMessage (pdf.js:12334)
    at sendStreamRequest (pdf.js:12151)
    at Object.error (pdf.js:12194)
    at eval (pdf.js:8419)
    at ZoneDelegate.invoke (zone.js:392)

Controller method

public async Task<IActionResult> Generate(string id)
{
    try
    {
        var stream = await _reportService.GenerateReportAsync(id);
        return new FileStreamResult(stream, "application/pdf");
    }
    catch(Exception ex)
    {
        throw;
    }            
}

Service method:

public async Task<Stream> GenerateReportAsync(string id)
{
    return await Services.InvokeAsync<Stream>("./Node/generate-pdf.js", Configuration.Url, id, new { format = "A4" });
}

generate-pdf.js:

const pdf = require('html-pdf');
const puppeteer = require('puppeteer');

module.exports = async function (result, url, id, options) {

const browser = await createBrowser();
const page = await browser.newPage();
const css = await browser.newPage();

await page.goto(`${url}/reports/${id}`, {
    waitUntil: 'networkidle2'
});

await css.goto(`${url}/styles.bundle.css`, {
    waitUntil: 'networkidle2'
});

await page.waitForSelector('.report-loaded');
let cssBody = await css.evaluate(() => `<style>${document.documentElement.innerHTML}</style>`);
let bodyHtml = await page.evaluate(() => document.documentElement.innerHTML);

bodyHtml = bodyHtml.replace('<link href="styles.bundle.css" rel="stylesheet">', cssBody);

browser.close();

pdf.create(cssBody + bodyHtml, options).toStream((error, stream) => stream.pipe(result.stream));
}

async function createBrowser() {
    return await puppeteer.launch({
        args: ['--no-sandbox', '--disable-setuid-sandbox']
    });
}

Answer 1

Looks like the generate-pdf.js script is using "html-pdf". This can be found on npm: https://www.npmjs.com/package/html-pdf

And it has a github page: https://github.com/marcbachmann/node-html-pdf

So the problem is going to be with the usage of that package, or some kind of bug in it. (well, that's an assumption on my part, I don't know this package at all and have no experience working with it)

At this point I'd try to figure out which version of that package is being used, check out the source code and try to find a hint in there.

This structure seems rather convoluted though. Why not just generate the PDF in the client in the first place, or generate it in the C# code? That it was working at some point shouldn't be an argument as you are now noticing this is proving difficult to maintain.