Live view direct upload s3: Push exif params to server before store the entity

Hi, i’m using liveview for s3 direct upload of images. I followed this guide:

I’m using also the auto_upload param.

Before the upload on s3, i resize the image and extract from it the exif params on the client with js.

I need push the exif params to backend before tell him that the upload is completed with:

How can i do?

Hi romaluca, I could not find “sign_form_upload” in ExAws.S3 from the guide, do you know? Thanks.