Sending Multipart Attachments

Overview

Some third-party systems only support receiving attachments using multipart/form-data requests.

Because multipart requests require the payload body, boundaries, and headers to be constructed together, this is implemented using a Unifi Multipart Helper service that assembles the multipart body as a temporary attachment, which can then be streamed as the outbound payload.

For more information on general attachment sending, see the Sending Attachments documentation.

The Unifi Multipart Helper is provided separately. Please contact us via support and we will share it with you.

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Sending Multipart Attachments

The multipart helper is used from the Stage to Request script to construct and stream a multipart request containing one or more attachments.

In this stage, Unifi:

• Collects eligible bonded attachments using AttachmentSender

• Builds a multipart body containing those attachments

• Stores the multipart body as a temporary attachment

• Streams that temporary attachment as the outbound request payload

Stage to Request Script

// ------------------------------------------------------------------
// Build and stream a multipart/form-data request containing attachments
// ------------------------------------------------------------------
var mp = new UnifiMultipartHelper();

// Use the current transaction as the host record for temporary
// attachments - these will be cleaned up later by an Event Action
mp.setHostRecord(transaction);

// Add each bonded attachment to the multipart body
var sender = new x_snd_eb.AttachmentSender(transaction, bond);
while (sender.next()) {
  mp.addAttachment('file', sender.attachment_id);
}

// Call the service to create the multipart body as a temporary attachment
var data_attachment_id = mp.createBody();

// Prepare request to stream the temporary attachment
headers['Content-Type'] = mp.getContentType();
payload = 'sys_attachment:' + data_attachment_id;

How this works

• Each call to mp.addAttachment() adds an attachment to the multipart body

• mp.createBody() assembles the multipart payload and writes it as a temporary attachment

• Setting the payload to sys_attachment:<id> instructs Unifi to stream the multipart body

• The Content-Type header includes the correct multipart boundary

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Cleaning Up Temporary Attachments

The multipart body is stored as a temporary attachment and must be removed once the transaction completes.

This is handled using an Event Action.

Event Action: Remove Temporary Attachments

Description Automatically remove the temporary attachments created for streaming multipart/form-data content.

Run Conditions

• Event: transaction.complete

Action Script

// Remove temporary attachments from the current transaction
var mp = new UnifiMultipartHelper();
mp.removeTemporaryAttachments(current);