Automate invoice processing with OCR, GPT-4 & Salesforce opportunity creation

PDF Invoice Extractor (AI)

End-to-end pipeline: Watch Drive ➜ Download PDF ➜ OCR text ➜ AI normalize to JSON ➜ Upsert Buyer (Account) ➜ Create Opportunity ➜ Map Products ➜ Create OLI via Composite API ➜ Archive to OneDrive.

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Node by node (what it does & key setup)

1) Google Drive Trigger

• Purpose: Fire when a new file appears in a specific Google Drive folder.
• Key settings:
  • Event: fileCreated
  • Folder ID: google drive folder id
  • Polling: everyMinute
  • Creds: googleDriveOAuth2Api
• Output: Metadata { id, name, ... } for the new file.

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2) Download File From Google

• Purpose: Get the file binary for processing and archiving.
• Key settings:
  • Operation: download
  • File ID: ={{ $json.id }}
  • Creds: googleDriveOAuth2Api
• Output: Binary (default key: data) and original metadata.

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3) Extract from File

• Purpose: Extract text from PDF (OCR as needed) for AI parsing.
• Key settings:
  • Operation: pdf
  • OCR: enable for scanned PDFs (in options)
• Output: JSON with OCR text at {{ $json.text }}.

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4) Message a model (AI JSON Extractor)

• Purpose: Convert OCR text into strict normalized JSON array (invoice schema).
• Key settings:
  • Node: @n8n/n8n-nodes-langchain.openAi
  • Model: gpt-4.1 (or gpt-4.1-mini)
  • Message role: system (the strict prompt; references {{ $json.text }})
  • jsonOutput: true
  • Creds: openAiApi
• Output (per item): $.message.content → the parsed JSON (ensure it’s an array).

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5) Create or update an account (Salesforce)

• Purpose: Upsert Buyer as Account using an external ID.
• Key settings:
  • Resource: account
  • Operation: upsert
  • External Id Field: tax_id__c
  • External Id Value: ={{ $json.message.content.buyer.tax_id }}
  • Name: ={{ $json.message.content.buyer.name }}
  • Creds: salesforceOAuth2Api
• Output: Account record (captures Id) for downstream Opportunity.

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6) Create an opportunity (Salesforce)

• Purpose: Create Opportunity linked to the Buyer (Account).
• Key settings:
  • Resource: opportunity
  • Name: ={{ $('Message a model').item.json.message.content.invoice.code }}
  • Close Date: ={{ $('Message a model').item.json.message.content.invoice.issue_date }}
  • Stage: Closed Won
  • Amount: ={{ $('Message a model').item.json.message.content.summary.grand_total }}
  • AccountId: ={{ $json.id }} (from Upsert Account output)
  • Creds: salesforceOAuth2Api
• Output: Opportunity Id for OLI creation.

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7) Build SOQL (Code / JS)

• Purpose: Collect unique product codes from AI JSON and build a SOQL query for PricebookEntry by Pricebook2Id.
• Key settings:
  • pricebook2Id (hardcoded in script): e.g., 01sxxxxxxxxxxxxxxx
  • Source lines: $('Message a model').first().json.message.content.products
• Output: { soql, codes }

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8) Query PricebookEntries (Salesforce)

• Purpose: Fetch PricebookEntry.Id for each Product2.ProductCode.
• Key settings:
  • Resource: search
  • Query: ={{ $json.soql }}
  • Creds: salesforceOAuth2Api
• Output: Items with Id, Product2.ProductCode (used for mapping).

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9) Code in JavaScript (Build OLI payloads)

• Purpose: Join lines with PBE results and Opportunity Id ➜ build OpportunityLineItem payloads.
• Inputs:
  • OpportunityId: ={{ $('Create an opportunity').first().json.id }}
  • Lines: ={{ $('Message a model').first().json.message.content.products }}
  • PBE rows: from previous node items
• Output: { body: { allOrNone:false, records:[{ OpportunityLineItem... }] } }
• Notes:
  • Converts discount_total ➜ per-unit if needed (currently commented for standard pricing).
  • Throws on missing PBE mapping or empty lines.

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10) Create Opportunity Line Items (HTTP Request)

• Purpose: Bulk create OLIs via Salesforce Composite API.
• Key settings:
  • Method: POST
  • URL: https://<your-instance>.my.salesforce.com/services/data/v65.0/composite/sobjects
  • Auth: salesforceOAuth2Api (predefined credential)
  • Body (JSON): ={{ $json.body }}
• Output: Composite API results (per-record statuses).

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11) Update File to One Drive

• Purpose: Archive the original PDF in OneDrive.
• Key settings:
  • Operation: upload
  • File Name: ={{ $json.name }}
  • Parent Folder ID: onedrive folder id
  • Binary Data: true (from the Download node)
  • Creds: microsoftOneDriveOAuth2Api
• Output: Uploaded file metadata.

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Data flow (wiring)

1. Google Drive Trigger → Download File From Google
2. Download File From Google
   • → Extract from File
   • → Update File to One Drive
3. Extract from File → Message a model
4. Message a model
   • → Create or update an account
5. Create or update an account → Create an opportunity
6. Create an opportunity → Build SOQL
7. Build SOQL → Query PricebookEntries
8. Query PricebookEntries → Code in JavaScript
9. Code in JavaScript → Create Opportunity Line Items

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Quick setup checklist

• 🔐 Credentials: Connect Google Drive, OneDrive, Salesforce, OpenAI.
• 📂 IDs:
  • Drive Folder ID (watch)
  • OneDrive Parent Folder ID (archive)
  • Salesforce Pricebook2Id (in the JS SOQL builder)
• 🧠 AI Prompt: Use the strict system prompt; jsonOutput = true.
• 🧾 Field mappings:
  • Buyer tax id/name → Account upsert fields
  • Invoice code/date/amount → Opportunity fields
  • Product name must equal your Product2.ProductCode in SF.
• ✅ Test: Drop a sample PDF → verify:
  • AI returns array JSON only
  • Account/Opportunity created
  • OLI records created
  • PDF archived to OneDrive

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Notes & best practices

• If PDFs are scans, enable OCR in Extract from File.
• If AI returns non-JSON, keep “Return only a JSON array” as the last line of the prompt and keep jsonOutput enabled.
• Consider adding validation on parsing.warnings to gate Salesforce writes.
• For discounts/taxes in OLI:
  • Standard OLI fields don’t support per-line discount amounts directly; model them in UnitPrice or custom fields.
• Replace the Composite API URL with your org’s domain or use the Salesforce node’s Bulk Upsert for simplicity.