Rendering Volumes file content programmatically

[lauraxyz]

Hi there!

I have some files stored in Volume, and I have a use case that I need to show the file content in a UI.  Say I have a REST API that already knows the Volume path to the file, is there any built-in feature from Databricks that i can use to help get the content?

one of the limitations Unity Catalog Volumes has is: "The DBFS endpoint for the REST API does not support volumes paths.",  what does this imply to my use case?

Thank you!

[cgrant · Accepted solution]

Hi @lauraxyz here is an example using the Databricks SDK in Python:

from databricks.sdk import WorkspaceClient

ws = WorkspaceClient()
image_path = '/Volumes/catalog/schema/volume/filename.jpg'

image_data = (
    ws.files.download(image_path) # download file
    .contents # pull out streamed response
    .read() # materialize bytes
)

From here, you can do whatever you like with the image bytes. For example:

from PIL import Image
from io import BytesIO

image = Image.open(BytesIO(image_data)) # open the image with pillow
image.show() #

If using a different language, we can always use the REST API directly, here is a quick Javascript example that uses the REST API (/api/2.0/fs/files):

// Set up API endpoint and headers
const host = "https://..."; // Replace with your workspace URL, leaving the end slash off
const token = "dapi..."; // Replace with your actual Databricks access token
const imagePath = '/Volumes/catalog/schema/volume/filename.jpg';

// Download image using REST API
fetch(`${host}/api/2.0/fs/files${imagePath}`, {
    headers: {
        'Authorization': `Bearer ${token}`
    }
})
.then(response => response.blob())
.then(blob => {
    const img = document.createElement('img');
    img.src=URL.createObjectURL(blob);
    document.body.appendChild(img);
})
.catch(error => console.error('Error:', error));

[lauraxyz]

Thank you @cgrant this is very helpful! 

Another related question:  if I want to accept user input from a UI and save that into a Volume, how should I do that?  I'm referring this Databricks API doc but it is only to update volume metadata instead of volume files.

[cgrant]

Hi @lauraxyz, the files API should be helpful, particularly the upload endpoint.