[英]Blob from buffer returns corrupted pdf
嘗試在 Firebase 函數上使用 Puppeteer 制作 pdf:發送 html 片段,返回 pdf。
但是pdf已損壞。 我認為問題在於返回文件/緩沖區。
// Server:
// setup
const func = require('firebase-functions');
const pptr = require('puppeteer');
const opts = { memory: '1GB', regions: ['europe-west3'] };
const call = func.runWith(opts).https.onCall
let browser = pptr.launch({ args: ['--no-sandbox'] });
// onCall
exports.makePdf = call(async (data) => {
// this works, does open the page testing with { headless: false }
const brws = await (await browser).createIncognitoBrowserContext();
const page = await brws.newPage();
await page.setContent(data, { waitUntil: 'domcontentloaded' });
const file = await page.pdf({ format: 'A4' });
await brws.close();
// the problem is returning the file
return file
});
當file
記錄在服務器上時,它是一個緩沖區<Buffer 25 50 44 46 2d 31 2e ... 11150 more bytes>
,但當登錄到客戶端時,它是一個對象,以十進制而不是十六進制{ data: {0: 37, 1: 80, 2: 68, 3: 70, ... }}
。
將其轉換回緩沖區? 轉換回十六進制? 哪個緩沖區?
// Client:
// send html and receive the file
let html = '<div><h1>Hi</h1></div>';
let file = ((await fns.makePdf(html))).data;
// also tried buffer = new Buffer.from(JSON.stringify(file));
let blob = new Blob(file, { type: 'application/pdf' });
// download the file
let a = document.createElement('a');
a.href = window.URL.createObjectURL(blob);
a.download = `${name}.pdf`;
a.click();
還是因為我下載錯誤( createObjectURL
)而導致 pdf 損壞? 或者 onCall 函數不能這樣使用?
重點是,不知道為什么它不起作用。 謝謝你的幫助
好的。 /插入詛咒眾神/
所以沒關系,您可以使用 onCall 而不是 onRequest,因為您最終可以從 json 響應創建一個 pdf。 onCall 好一點的原因是因為你不需要打擾 cors 或 headers,谷歌為你做。
// setup
const func = require('firebase-functions');
const pptr = require('puppeteer');
const opts = { memory: '1GB', regions: ['europe-west3'] };
const call = func.runWith(opts).https.onCall
// this runs outside of the function because it might not be killed off
// if the function is called quickly in succession (lookup details on
// google cloud functions docs)
let browser = pptr.launch({ args: ['--no-sandbox'] });
// the main function
exports.makePdf = call(async (data) => {
// prep puppeteer so it can print the pdf
const brws = await (await browser).createIncognitoBrowserContext();
const page = await brws.newPage();
await page.setContent(data);
const file = await page.pdf({
format: 'A4',
printBackground: false,
margin: { left: 0, top: 0, right: 0, bottom: 0 }
});
brws.close();
// and just return the stream
return file
});
訣竅在於客戶端。 我會在評論中注明。
// so this is inside some function, has to be because it needs to be async
var a, blob, buffer, d, file, html, i, result;
// this html is for testing, it would obviously be gathered in another way
html = '<div><h1>Hi</h1></div>';
// we call the function from the client
// fns is my shorthand object defined on Google Functions initialization
// it is literally: f.httpsCallable('makePdf') where f is the functions object
// you get from initialization
file = ((await fns.makePdf(html))).data;
// additional .data is needed because onCall automatically wraps
// now the point
// 1. convert object to array
result = []; for (i in file) {
d = file[i]; result.push(d);
}
// 2. convert that to a Uint8Array
buffer = new Uint8Array(result);
// 3. create a blob, BUT the buffer needs to go inside another array
blob = new Blob([buffer], { type: 'application/pdf' });
// finally, download it
a = document.createElement('a');
a.href = window.URL.createObjectURL(blob);
a.download = `${path}.pdf`;
a.click();
我發現這個項目與你的相似,我發現了一個不同之處,在緩沖區返回中你需要指定標頭和 HTTP 代碼,客戶端瀏覽器可能會誤解來自服務器的對象。
這是另一個項目的返回段
const pdfBuffer = await page.pdf({ printBackground: true });
res.set("Content-Type", "application/pdf");
res.status(200).send(pdfBuffer);
代碼中的所有內容看起來都正確,如果將 PDF 從 dec 轉換為 hex 返回相同的字符串,我認為這可能是一個很好的解決方法。
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