How to download a file from blob and send it has a file response

Question

I have a client page which will list all the file in the container, on choosing a file the filename along with the container name is sent to the server. The server should initiate the file download and should send the file as response to the client request, please refer to the image below:

I tried with get_blob_to_stream

@app.route("/blobs/testDownload/")
def testDownload():
  container_name =request.args.get("containerName")
  print(container_name)
  local_file_name= request.args.get("fileName")

  with BytesIO() as input_blob:
     with BytesIO() as output_blob:
    
    # Download as a stream
        block_blob_service.get_blob_to_stream(container_name, local_file_name, input_blob)
        copyfileobj(input_blob, output_blob)
        newFile = str(output_blob.getvalue())
        with open("file.txt","a") as f:
            f.write(newFile)
            f.close()
        
return send_file('file.txt',attachment_filename='sample.txt',as_attachment=True,mimetype='text/plain')

But the file which is getting downloaded is in only text file format, I want to download file irrespective of its format. and I know this is not the right way to download file via Web API.

Answer 1

You're using a fixed file-name "file.txt" for all the blobs which may be the reason. Using a stream seems useless here. try get_blob_to_path() instead, check out the following modified code:

--- // your code // ---

block_blob_service.get_blob_to_path(container_name, local_file_name, local_file_name)
# notice that I'm reusing the local_file_name here, hence no input/output blobs are required return send_file(local_file_name,attachment_filename=local_file_name,as_attachment=True,mimetype='text/plain')

Complete Code:

@app.route("/blobs/testDownload/")
 def testDownload():
 container_name =request.args.get("containerName")
 print(container_name)
 local_file_name= request.args.get("fileName")

# Download as a file
block_blob_service.get_blob_to_path(container_name, local_file_name, local_file_name)


return send_file(local_file_name,attachment_filename=local_file_name,as_attachment=True,mimetype='text/plain')

See if that works!