What is it?
A new flow notation called SFDXE Upload Attachment allows file uploads to a Salesforce object as an attachment. For example, an audio recording can be attached to a lead or case. This new data exchange notation includes configurable parameters to define the type and name of the file being uploaded.
Ability to upload binary files accessible through public URLs to records in Salesforce from flow.
Good to Know
While this feature was primarily developed to allow for uploading recordings to Salesforce to satisfy an upload to lead requirement it can be leveraged to upload any file that flow is able to access through a publicly available URL.
Flow Designer Reference