Examples of downloading files from Azure Blob Storage

Question

I am able to upload files to Azure blob storage via Node/Express without issue, but have found very minimal documentation/full examples of how to download a file. I found this on the tutorial page, but did not have any luck:

blobSvc.getBlobToStream('mycontainer', 'myblob', fs.createWriteStream('output.txt'), function(error, result, response){
  if(!error){
    // blob retrieved
  }
});

Has anyone else used node.js/express to download files from Azure blob storage? Did you use Azure, or another method (ex. Request). Could you share how to get a file from Azure and stream it to a folder?

Answer 1

There's a full tutorial on using Azure Storage Blobs with Node.js here. The tutorial mentions getBlobToLocalFile which sounds like what you're probably looking for. The syntax for this method should be extremely similar to getBlobToStream but instead of a stream you'll provide a file path.

Answer 2

I was creating a function that downloads a folder(virtual) of blobs and returns a zip file. The easiest implementation was to download them as files with getBlobToLocalFile, export as a .zip and finally delete the temp file. This might not be the best solution, but it's easier to implement. I know it's not the most efficient way, but it's good enough for me.

Step 1, get list of blobs:

 blobService.listBlobsSegmentedWithPrefix(
  containerName,
  prefix,
  null,
  { delimiter: "", maxResults: 100 },
  (err, result) => {
    if (err) {
      reject(err);
    } else {
      resolve(result.entries);
    }
  }
);

Step 2, save locally:

 blobs.map(blob => {
  blobService.getBlobToLocalFile(
    containerName,
    blob.name,
    `${baseDir}/${blob.name}`,
    (err, blob) => {
      if (err) {
        //handle error
      } else {
        count++;
        //do something after they all save
    }
  );
});