ExpressJS和PDFKit-在内存中生成PDF并发送给客户端以进行下载 [英] ExpressJS and PDFKit - generate a PDF in memory and send to client for download
问题描述
在我的 api
路由器中,有一个名为 generatePDF
的函数,该函数旨在使用PDFKit模块在内存中生成PDF文件,然后发送给客户端进行下载而不是显示
In my api
router, there is a function called generatePDF
which aims to use PDFKit module to generate a PDF file in memory and send to client for download instead of displaying only.
在 api.js
中:
var express = require('express');
var router = express.Router();
const PDFDocument = require('pdfkit');
router.get('/generatePDF', async function(req, res, next) {
var myDoc = new PDFDocument({bufferPages: true});
myDoc.pipe(res);
myDoc.font('Times-Roman')
.fontSize(12)
.text(`this is a test text`);
myDoc.end();
res.writeHead(200, {
'Content-Type': 'application/pdf',
'Content-disposition': 'attachment;filename=test.pdf',
'Content-Length': 1111
});
res.send( myDoc.toString('base64'));
});
module.exports = router;
这不起作用.错误消息为(节点:11444)UnhandledPromiseRejectionWarning:错误[ERR_HTTP_HEADERS_SENT]:将标头发送到客户端后无法设置标头.
This does not work. The error message is (node:11444) UnhandledPromiseRejectionWarning: Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
.
我该如何解决该问题并使它正常工作?
How can I go about fixing the issue and getting it work?
另外,一个相关的问题是我如何才能将PDF生成的业务逻辑与路由器分开并将它们链接起来?
Also, a relevant question would be how I can separate the business logic of PDF generation from the router and chain them up?
推荐答案
完整解决方案.
var express = require('express');
var router = express.Router();
const PDFDocument = require('pdfkit');
router.get('/generatePDF', async function(req, res, next) {
var myDoc = new PDFDocument({bufferPages: true});
let buffers = [];
myDoc.on('data', buffers.push.bind(buffers));
myDoc.on('end', () => {
let pdfData = Buffer.concat(buffers);
res.writeHead(200, {
'Content-Length': Buffer.byteLength(pdfData),
'Content-Type': 'application/pdf',
'Content-disposition': 'attachment;filename=test.pdf',})
.end(pdfData);
});
myDoc.font('Times-Roman')
.fontSize(12)
.text(`this is a test text`);
myDoc.end();
});
module.exports = router;
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