I am attempting to grab a PDF stored in Azure Blob Storage via a node backend and then serve that PDF file to a React Frontend. I am using Microsofts @azure/storage-blob
with a BlockBlobClient but every example I find online converts the readableStreamBody
to a string. The blob has a content type of application/pdf
. Ive tried passing the readableStreamBody
and the pure output to the frontend but those result in broken pdf's. I also followed the documentation online and made it a string and passed that to the frontend. That produced a PDF that would open and had the proper amount of pages but was completly blank.
Node.js Code on the Backend
app.get('/api/file/:company/:file', (req, res) => {
const containerClient = blobServiceClient.getContainerClient(req.params.company);
const blockBlobClient = containerClient.getBlockBlobClient(req.params.file);
blockBlobClient.download(0)
.then(blob => streamToString(blob.readableStreamBody))
.then(response => res.send(response))
});
FrontEnd Code
getFileBlob = (company,file) => {
axios(`/api/file/${company}/${file}`, { method: 'GET', responseType: 'blob'})
.then(response => {
const file = new Blob(
[response.data],
{type: 'application/pdf'});
const fileURL = URL.createObjectURL(file);
window.open(fileURL);
})
.catch(error => {
console.log(error);
});
}
This might help you, its working for me.
Node
var express = require('express');
const { BlobServiceClient } = require('@azure/storage-blob');
var router = express.Router();
const AZURE_STORAGE_CONNECTION_STRING =
'YOUR_STRING';
async function connectAzure() {
// Create the BlobServiceClient object which will be used to create a container client
const blobServiceClient = BlobServiceClient.fromConnectionString(
AZURE_STORAGE_CONNECTION_STRING
);
const containerName = 'filestorage';
const blobName = 'sample.pdf';
console.log('\nConnecting container...');
console.log('\t', containerName);
// Get a reference to a container
const containerClient = blobServiceClient.getContainerClient(containerName);
// Get a block blob client
const blockBlobClient = containerClient.getBlockBlobClient(blobName);
for await (const blob of containerClient.listBlobsFlat()) {
console.log('\t', blob.name);
}
const downloadBlockBlobResponse = await blockBlobClient.download(0);
const data = await streamToString(downloadBlockBlobResponse.readableStreamBody)
return data;
}
async function streamToString(readableStream) {
return new Promise((resolve, reject) => {
const chunks = [];
readableStream.on('data', data => {
chunks.push(data.toString());
});
readableStream.on('end', () => {
resolve(chunks.join(''));
});
readableStream.on('error', reject);
});
}
router.get('/', async function(req, res, next) {
const data = await connectAzure();
res.send({data}).status(200);
});
module.exports = router;
Front-end
function createFile() {
fetch('/createfile').then(res => {
res.json().then(data => {
var blob = new Blob([data.data], { type: 'application/pdf' });
var fileURL = URL.createObjectURL(blob);
if (filename) {
if (typeof a.download === 'undefined') {
window.location.href = fileURL;
} else {
window.open(fileURL, '_blank');
}
}
})
}).catch(err => console.log(err))
}
HTML
<body><h1>Express</h1><p>Welcome to Express</p><button onclick="createFile()">Create File</button></body>
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