Multi-Channel Order Fulfillment to QuickBooks Online Automation (n8n)

1. **Create Workflow & Webhook Node**: In n8n, start with a 'Webhook' node. Set the HTTP Method to POST. This URL will be placed in your Multi-Channel tool as the 'Order Created' notification endpoint. 2. **Configure Credentials**: Go to the 'Credentials' tab in n8n and add 'QuickBooks Online OAuth2'. Follow the prompt to authorize n8n to access your QuickBooks company file. 3. **Transform Data (Set Node)**: Add a 'Set' node to map the incoming JSON from the Webhook into clean variables. Use expressions like `{{ $json.body.order_total }}` to normalize fields before they hit QuickBooks. 4. **Search for Existing Customer**: Use the 'QuickBooks' node with the 'Customer' resource and 'Get All' operation. Use a filter expression: `DisplayName = {{ $node["Set"].json["customer_name"] }}` to check if they exist. 5. **Branching Logic (IF Node)**: Use an 'IF' node to check the length of the results from the search step. If `{{ $node["QuickBooks"].json.length }} === 0`, route to a 'Create Customer' node; otherwise, proceed to the next step. 6. **Create Sales Receipt**: Connect to a 'QuickBooks' node, select 'Sales Receipt' and 'Create'. Map your fields using n8n expressions. Ensure the 'Line Items' are mapped by toggling the 'Expressions' mode for the item list to handle multiple products in one order. 7. **Tax & Discount Processing**: Use the 'Code' node (JavaScript) if complex tax calculations or multi-currency conversions are required before sending the final payload to QuickBooks. 8. **Inventory Adjustment**: Add another QuickBooks node to 'Update' an Item. This allows you to decrease the 'Quantity on Hand' based on the quantity sold in Tool A. 9. **Global Error Handling**: Create a separate workflow with an 'Error Trigger'. In your main workflow, go to 'Settings' and select this error workflow. This ensures that if the QuickBooks API is down, you are alerted via Slack or Email immediately.

| Data Field (Source) | QuickBooks Field | n8n Expression / Strategy | Required | | :--- | :--- | :--- | :--- | | Order ID | `DocNumber` | `{{ $json["id"].toString() }}` | Yes | | Net Total | `TotalAmt` | `{{ $json["total"] - $json["tax"] }}` | Yes | | Customer Email | `PrimaryEmailAddr` | `{{ $json["email"].toLowerCase() }}` | Yes | | Product SKU | `Line.SalesItemLineDetail.ItemRef` | `{{ $json["sku"] }}` (Map to QB Item ID) | Yes | | Shipping City | `ShipAddr.City` | `{{ $json["shipping_address"]["city"] }}` | No | | Order Date | `TxnDate` | `{{ $now.toFormat('yyyy-MM-dd') }}` | Yes | | Channel Name | `PrivateNote` | `Source: {{ $json["channel"] }}` | No |

- **Rate Limiting**: QuickBooks Online has a limit of 40 concurrent requests. If syncing bulk historical data, use the n8n 'Split in Batches' node (set to 20-30 items) with a 'Wait' node of 1 second to avoid 429 Errors. - **Data Casting**: n8n treats Webhook data as strings. QuickBooks requires numeric values for 'TotalAmt' and 'Qty'. Wrap your expressions in `Number()` where necessary. - **Duplicate Customers**: QuickBooks throws an error if you try to create a Customer with a `DisplayName` that already exists. Always perform a lookup before the Create action. - **Sandbox vs Production**: n8n credentials are environment-specific. Ensure you switch from 'QuickBooks Sandbox' to 'QuickBooks Production' and refresh the OAuth2 token before going live.

- [ ] **Webhook Handshake**: Send a test payload from Tool A and verify the 'Webhook' node in n8n receives the full JSON body. - [ ] **Customer Deduplication**: Run the workflow with an existing customer email to ensure a duplicate record isn't created. - [ ] **Line Item Format**: Verify that orders with multiple unique SKUs are correctly creating multiple line items in the QuickBooks Sales Receipt (use the 'Execute Workflow' button to inspect the output). - [ ] **Token Refresh**: Check n8n Executions after 24 hours to ensure the QuickBooks OAuth2 token is auto-refreshing correctly. - [ ] **Error Workflow**: Manually break a node (e.g., use an invalid SKU) and confirm the Error Trigger workflow sends a notification.