使用 PDFKit 在 S3 中即时存储 PDF
Using PDFKit to store a PDF in S3 on the fly
我正在尝试创建一些图像的 pdf(datauri 格式)是 nodejs 并将 pdf 存储在我的 S3 中。函数的return需要提供文件的s3URL
我在这里使用 parse-server 作为服务器,使用 node-canvas 创建图像的 canvas,然后使用 PDFKit 从 canvas 元素创建 pdf。 (jsPdf 没有成功)。现在我希望使用 AWS-SDK 将此 pdf 发送到我的 s3,最后 return 文件的 URL。下面是我的代码,一直有效到 canvas 代。我不知道是否首先创建了 pdf,甚至在发送到 s3 之前。哦!整个事情在 heroku 上 运行。
Parse.Cloud.define('getBulkMeta',async (req)=>{
const PDFDocument = require('pdfkit'),
{Canvas,loadImage} = require('canvas');
try {
let baseImg = await loadImage('data:image/png;base64,'+req.params.labels[0]);
let labels = req.params.labels,
allCanvas = [],
rowH = baseImg.naturalHeight,
rowW = baseImg.naturalWidth,
perpage = req.params.size[1],
pages = Math.ceil(labels.length/perpage),
imgInd = 0,
g = 10;
size = req.params.size[0];
for(var p=0;p<pages;p++){
let canvas = new Canvas(rowW*((size=='A4')?2:1),rowH*((size=='A4')?2:1)),
ctx = canvas.getContext("2d");
ctx.beginPath();
ctx.rect(0,0,canvas.width,canvas.height)
ctx.fillStyle = "#fff";
ctx.fill();
if(perpage == 1){
let img = await loadImage('data:image/png;base64,'+labels[imgInd++]);
ctx.drawImage(img,g,g,rowW-(2*g),rowH-(2*g));
} else {
var thisImgInd = 0;
for (var r=0;r<2;r++){
for(var c=0;c<2;c++){
let img = await loadImage('data:image/png;base64,'+labels[imgInd++]);
ctx.drawImage(img,g+(c*(rowW-g/2)),g+(r*(rowH-g/2)),rowW-(1.5*g),rowH-(1.5*g));
thisImgInd++
if(thisImgInd>=perpage||imgInd>=labels.length){break;}
}
if(thisImgInd>=perpage||imgInd>=labels.length){break;}
}
}
allCanvas.push(canvas)
}
var thisPDF = new PDFDocument({layout: 'landscape',size:size});
var bcoded;
thisPDF.pipe(()=>{bcoded = new Buffer.from(thisPDF).toString('base64')});
allCanvas.forEach((c,i)=>{
if(i){thisPDF.addPage();}
thisPDF.image(c.toDataURL(),0,0,thisPDF.page.width,thisPDF.page.width);
})
thisPDF.end();
const S3_BUCKET = process.env.S3_BUCKET;
aws.config.region = process.env.AWS_REGION;
aws.config.signatureVersion = 'v4';
let s3 = new aws.S3();
let fileName = req.params.name;
let s3Params = {
Bucket: S3_BUCKET,
Body: bcoded,
Key: fileName,
ContentType : 'application/pdf',
ACL: 'public-read'
};
s3.putObject(s3Params, (err, data) => {
if(err){
console.log('\n\n\n\n\n\n\n'+err+'\n\n\n\n\n\n\n');
throw 'Error: '+ (err);
}
let returnData = {
signedRequest: data,
url: `https://${S3_BUCKET}.s3.amazonaws.com/${fileName}`
};
return (returnData);
})
} catch (e) {throw e;}
})
更新。我已经使用以下代码将 pdf 文件保存在 s3 中:
Parse.Cloud.define('getBulkMeta',async (req)=>{
const PDFDocument = require('pdfkit'),
{Canvas,loadImage} = require('canvas');
try {
let baseImg = await loadImage('data:image/png;base64,'+req.params.labels[0]);
let labels = req.params.labels,
allCanvas = [],
rowH = baseImg.naturalHeight,
rowW = baseImg.naturalWidth,
perpage = req.params.size[1],
pages = Math.ceil(labels.length/perpage),
imgInd = 0,
g = 10;
size = req.params.size[0];
for(var p=0;p<pages;p++){
let canvas = new Canvas(),
ctx = canvas.getContext("2d");
canvas.height = rowH*((size=='A4')?2:1);
canvas.width = rowW*((size=='A4')?2:1);
ctx.beginPath();
ctx.rect(0,0,canvas.width,canvas.height)
ctx.fillStyle = "#fff";
ctx.fill();
if(perpage == 1){
let img = await loadImage('data:image/png;base64,'+labels[imgInd++]);
ctx.drawImage(img,g,g,rowW-(2*g),rowH-(2*g));
} else {
var thisImgInd = 0;
for (var r=0;r<2;r++){
for(var c=0;c<2;c++){
let img = await loadImage('data:image/png;base64,'+labels[imgInd++]);
ctx.drawImage(img,g+(c*(rowW-g/2)),g+(r*(rowH-g/2)),rowW-(1.5*g),rowH-(1.5*g));
thisImgInd++
if(thisImgInd>=perpage||imgInd>=labels.length){break;}
}
if(thisImgInd>=perpage||imgInd>=labels.length){break;}
}
}
allCanvas.push(canvas)
}
var thisPDF = new PDFDocument({layout: 'landscape',size:size});
let buffers = [],pdfData,returnData='Hi';
thisPDF.on('data', buffers.push.bind(buffers));
thisPDF.on('end',() => {
pdfData = Buffer.concat(buffers);
const S3_BUCKET = process.env.S3_BUCKET;
aws.config.region = process.env.AWS_REGION;
aws.config.signatureVersion = 'v4';
let s3 = new aws.S3();
let fileName = req.params.name;
let s3Params = {
Bucket: S3_BUCKET,
Body: pdfData,
Key: (+new Date())+'-'+fileName,
ContentType : 'application/pdf',
ACL: 'public-read'
};
s3.putObject(s3Params,(err, data) => {
delete pdfData,thisPDF;
pdfData = null;thisPDF = null;
if(err){ throw 'Error: '+ (err); }
returnData = { signedRequest: data, url: `https://${S3_BUCKET}.s3.amazonaws.com/${fileName}` };
})
})
allCanvas.forEach((c,i)=>{
if(i){thisPDF.addPage();}
thisPDF.image(c.toDataURL(),0,0,{fit:[thisPDF.page.width,thisPDF.page.height]});
})
thisPDF.end();
return returnData;
} catch (e) {throw e;}
})
但是,returnData
总是给出 "Hi" 作为输出,而且函数似乎也没有关闭 - Heroku 每次都会抛出内存超出错误。
由于您使用异步函数创建 PDF 并将其发送到 S3,因此您的云函数会在这些操作实际完成之前返回。这就是为什么您的 returnData
变量中总是有 Hi
的原因。您需要创建一个承诺并等待这个承诺在这两个操作结束时完成。它应该是这样的:
await (new Promise((resolve, reject) => {
var thisPDF = new PDFDocument({layout: 'landscape',size:size});
let buffers = [];
thisPDF.on('data', buffers.push.bind(buffers));
thisPDF.on('end',() => {
pdfData = Buffer.concat(buffers);
const S3_BUCKET = process.env.S3_BUCKET;
aws.config.region = process.env.AWS_REGION;
aws.config.signatureVersion = 'v4';
let s3 = new aws.S3();
let fileName = req.params.name;
let s3Params = {
Bucket: S3_BUCKET,
Body: pdfData,
Key: (+new Date())+'-'+fileName,
ContentType : 'application/pdf',
ACL: 'public-read'
};
s3.putObject(s3Params,(err, data) => {
delete pdfData,thisPDF;
pdfData = null;thisPDF = null;
if(err){ reject(err); }
returnData = { signedRequest: data, url: `https://${S3_BUCKET}.s3.amazonaws.com/${fileName}` };
resolve();
})
})
});
顺便说一句,您可以使用 Parse S3 Adapter 并将 PDF 保存为常规 Parse 文件,而不是使用 AWS SDK。
我正在尝试创建一些图像的 pdf(datauri 格式)是 nodejs 并将 pdf 存储在我的 S3 中。函数的return需要提供文件的s3URL
我在这里使用 parse-server 作为服务器,使用 node-canvas 创建图像的 canvas,然后使用 PDFKit 从 canvas 元素创建 pdf。 (jsPdf 没有成功)。现在我希望使用 AWS-SDK 将此 pdf 发送到我的 s3,最后 return 文件的 URL。下面是我的代码,一直有效到 canvas 代。我不知道是否首先创建了 pdf,甚至在发送到 s3 之前。哦!整个事情在 heroku 上 运行。
Parse.Cloud.define('getBulkMeta',async (req)=>{
const PDFDocument = require('pdfkit'),
{Canvas,loadImage} = require('canvas');
try {
let baseImg = await loadImage('data:image/png;base64,'+req.params.labels[0]);
let labels = req.params.labels,
allCanvas = [],
rowH = baseImg.naturalHeight,
rowW = baseImg.naturalWidth,
perpage = req.params.size[1],
pages = Math.ceil(labels.length/perpage),
imgInd = 0,
g = 10;
size = req.params.size[0];
for(var p=0;p<pages;p++){
let canvas = new Canvas(rowW*((size=='A4')?2:1),rowH*((size=='A4')?2:1)),
ctx = canvas.getContext("2d");
ctx.beginPath();
ctx.rect(0,0,canvas.width,canvas.height)
ctx.fillStyle = "#fff";
ctx.fill();
if(perpage == 1){
let img = await loadImage('data:image/png;base64,'+labels[imgInd++]);
ctx.drawImage(img,g,g,rowW-(2*g),rowH-(2*g));
} else {
var thisImgInd = 0;
for (var r=0;r<2;r++){
for(var c=0;c<2;c++){
let img = await loadImage('data:image/png;base64,'+labels[imgInd++]);
ctx.drawImage(img,g+(c*(rowW-g/2)),g+(r*(rowH-g/2)),rowW-(1.5*g),rowH-(1.5*g));
thisImgInd++
if(thisImgInd>=perpage||imgInd>=labels.length){break;}
}
if(thisImgInd>=perpage||imgInd>=labels.length){break;}
}
}
allCanvas.push(canvas)
}
var thisPDF = new PDFDocument({layout: 'landscape',size:size});
var bcoded;
thisPDF.pipe(()=>{bcoded = new Buffer.from(thisPDF).toString('base64')});
allCanvas.forEach((c,i)=>{
if(i){thisPDF.addPage();}
thisPDF.image(c.toDataURL(),0,0,thisPDF.page.width,thisPDF.page.width);
})
thisPDF.end();
const S3_BUCKET = process.env.S3_BUCKET;
aws.config.region = process.env.AWS_REGION;
aws.config.signatureVersion = 'v4';
let s3 = new aws.S3();
let fileName = req.params.name;
let s3Params = {
Bucket: S3_BUCKET,
Body: bcoded,
Key: fileName,
ContentType : 'application/pdf',
ACL: 'public-read'
};
s3.putObject(s3Params, (err, data) => {
if(err){
console.log('\n\n\n\n\n\n\n'+err+'\n\n\n\n\n\n\n');
throw 'Error: '+ (err);
}
let returnData = {
signedRequest: data,
url: `https://${S3_BUCKET}.s3.amazonaws.com/${fileName}`
};
return (returnData);
})
} catch (e) {throw e;}
})
更新。我已经使用以下代码将 pdf 文件保存在 s3 中:
Parse.Cloud.define('getBulkMeta',async (req)=>{
const PDFDocument = require('pdfkit'),
{Canvas,loadImage} = require('canvas');
try {
let baseImg = await loadImage('data:image/png;base64,'+req.params.labels[0]);
let labels = req.params.labels,
allCanvas = [],
rowH = baseImg.naturalHeight,
rowW = baseImg.naturalWidth,
perpage = req.params.size[1],
pages = Math.ceil(labels.length/perpage),
imgInd = 0,
g = 10;
size = req.params.size[0];
for(var p=0;p<pages;p++){
let canvas = new Canvas(),
ctx = canvas.getContext("2d");
canvas.height = rowH*((size=='A4')?2:1);
canvas.width = rowW*((size=='A4')?2:1);
ctx.beginPath();
ctx.rect(0,0,canvas.width,canvas.height)
ctx.fillStyle = "#fff";
ctx.fill();
if(perpage == 1){
let img = await loadImage('data:image/png;base64,'+labels[imgInd++]);
ctx.drawImage(img,g,g,rowW-(2*g),rowH-(2*g));
} else {
var thisImgInd = 0;
for (var r=0;r<2;r++){
for(var c=0;c<2;c++){
let img = await loadImage('data:image/png;base64,'+labels[imgInd++]);
ctx.drawImage(img,g+(c*(rowW-g/2)),g+(r*(rowH-g/2)),rowW-(1.5*g),rowH-(1.5*g));
thisImgInd++
if(thisImgInd>=perpage||imgInd>=labels.length){break;}
}
if(thisImgInd>=perpage||imgInd>=labels.length){break;}
}
}
allCanvas.push(canvas)
}
var thisPDF = new PDFDocument({layout: 'landscape',size:size});
let buffers = [],pdfData,returnData='Hi';
thisPDF.on('data', buffers.push.bind(buffers));
thisPDF.on('end',() => {
pdfData = Buffer.concat(buffers);
const S3_BUCKET = process.env.S3_BUCKET;
aws.config.region = process.env.AWS_REGION;
aws.config.signatureVersion = 'v4';
let s3 = new aws.S3();
let fileName = req.params.name;
let s3Params = {
Bucket: S3_BUCKET,
Body: pdfData,
Key: (+new Date())+'-'+fileName,
ContentType : 'application/pdf',
ACL: 'public-read'
};
s3.putObject(s3Params,(err, data) => {
delete pdfData,thisPDF;
pdfData = null;thisPDF = null;
if(err){ throw 'Error: '+ (err); }
returnData = { signedRequest: data, url: `https://${S3_BUCKET}.s3.amazonaws.com/${fileName}` };
})
})
allCanvas.forEach((c,i)=>{
if(i){thisPDF.addPage();}
thisPDF.image(c.toDataURL(),0,0,{fit:[thisPDF.page.width,thisPDF.page.height]});
})
thisPDF.end();
return returnData;
} catch (e) {throw e;}
})
但是,returnData
总是给出 "Hi" 作为输出,而且函数似乎也没有关闭 - Heroku 每次都会抛出内存超出错误。
由于您使用异步函数创建 PDF 并将其发送到 S3,因此您的云函数会在这些操作实际完成之前返回。这就是为什么您的 returnData
变量中总是有 Hi
的原因。您需要创建一个承诺并等待这个承诺在这两个操作结束时完成。它应该是这样的:
await (new Promise((resolve, reject) => {
var thisPDF = new PDFDocument({layout: 'landscape',size:size});
let buffers = [];
thisPDF.on('data', buffers.push.bind(buffers));
thisPDF.on('end',() => {
pdfData = Buffer.concat(buffers);
const S3_BUCKET = process.env.S3_BUCKET;
aws.config.region = process.env.AWS_REGION;
aws.config.signatureVersion = 'v4';
let s3 = new aws.S3();
let fileName = req.params.name;
let s3Params = {
Bucket: S3_BUCKET,
Body: pdfData,
Key: (+new Date())+'-'+fileName,
ContentType : 'application/pdf',
ACL: 'public-read'
};
s3.putObject(s3Params,(err, data) => {
delete pdfData,thisPDF;
pdfData = null;thisPDF = null;
if(err){ reject(err); }
returnData = { signedRequest: data, url: `https://${S3_BUCKET}.s3.amazonaws.com/${fileName}` };
resolve();
})
})
});
顺便说一句,您可以使用 Parse S3 Adapter 并将 PDF 保存为常规 Parse 文件,而不是使用 AWS SDK。