Create incoming invoices in work4all from email attachments with OpenAI

Description

Quick Overview
This sub-workflow receives an email item with binary attachments, uses an OpenAI-compatible chat completions endpoint to detect and extract invoice fields from PDF/XML/JSON files, and then creates an incoming invoice in work4all with the relevant original attachments.

How it works
Receives an item from a parent workflow via Execute Workflow Trigger containing the email metadata and binary attachments.
Checks whether any attachments exist and skips processing if none are provided.
Builds a chat-completions request that includes a strict JSON extraction prompt plus any readable PDF/XML/JSON attachment content.
Sends the request to an OpenAI-compatible HTTP endpoint and parses the returned JSON to determine whether an invoice is present.
If an invoice is found, filters to the relevant attachments, normalizes fields (forces EUR and converts dates), and adds entry/receipt dates from the email receivedDateTime.
Creates the incoming invoice in work4all and returns the created invoice data and any errors along with the original message ID.
If no invoice is found (or no readable attachments exist), returns a minimal “success” result with the original message ID to the caller.

Setup
Add a work4all OAuth2 credential and ensure the verified work4all community node is installed.
Add an OpenAI-compatible API credential and set the chat-completions URL (and required headers) in the HTTP Request step.
Update the model name in the “Build LLM messages” code to one that supports file/PDF input for your chosen provider.
Ensure the parent workflow passes a single email item with binary attachment properties plus id and receivedDateTime fields when calling this sub-workflow.