Catch failed invoice extractions with easybits, Slack, and Google Drive

Description

What This Workflow Does
Monitors incoming invoice emails and catches extraction failures before they slip through. When easybits Extractor can't extract the invoice number from an attachment, the workflow sends a Slack alert to finance so nothing gets lost. Successfully extracted invoices are archived to Google Drive – only clean, validated files land there.

How It Works
Gmail Trigger – Polls for new emails with attachments every minute
Extraction – The attachment is sent to easybits Extractor
Validation – An IF node checks if invoice_number was successfully extracted
On failure – A Slack alert is sent to finance for manual review
On success – The file is merged back with its extracted data and archived to Google Drive

Why This Matters
Extractor returns null when it can't confidently identify a data point – which is the right behavior (better than hallucinating a value). But without a safety net, those nulls can propagate into your Sheets, your approval flow, or your accounting system. This workflow makes silent failures visible.

Setup Guide

1. Set Up Your easybits Extractor Pipeline
Go to extractor.easybits.tech and create a pipeline for invoice extraction
Make sure your pipeline includes an invoice_number field (this is the field the validation step checks)
Click "Auto-Map Fields" to let the Extractor suggest fields from a sample invoice, then review and save
Copy your Pipeline ID and API Key from Pipeline Details → View Pipeline

> 💡 Tip: You can validate against any field that's critical for your use case – just swap invoice_number in the IF node for whatever field you define as mandatory (e.g. total_amount, vendor_name).

2. Install the easybits Extractor Node
n8n Cloud:* The node is *verified** – just search for "easybits Extractor" in the node panel
Self-hosted:* Go to *Settings → Community Nodes → Install** and enter @easybits/n8n-nodes-extractor

3. Connect Your Credentials
Gmail Trigger: New Invoice – Add your Gmail OAuth2 credential and confirm the polling interval
easybits: Extract Invoice Number – Enter your Pipeline ID and API Key
Slack: Notify – Extraction Failed – Add your Slack credential and update the target user or channel
Upload to Invoice Folder – Add your Google Drive credential and select the folder where archived invoices should land

4. Adjust the Validation Field (Optional)
The IF node currently checks {{ $json.data.invoice_number }} with the is empty operator. If your pipeline uses a different critical field, update this expression to point at that field.

5. Activate & Test
Click Active in the top-right corner of n8n
Send yourself a test email with an invoice that's hard to read (blurry photo, scanned copy with poor contrast) to force an extraction failure
Confirm you receive the Slack alert
Send a clean invoice to confirm the success branch uploads correctly to Google Drive

🔄 Extending This Pattern
This error handling branch can sit in front of any workflow in the easybits series:

Invoice Approval Pipeline** – catch failed extractions before they hit Slack approval
Document Classification Pipeline** – flag documents that couldn't be classified confidently
Receipt-to-Sheet** – prevent null rows from polluting your expense tracker

The pattern is always the same: Extractor → IF (is empty) → error branch alongside your main path.