Odoo Expense Approval Workflow: Slack + Gmail via n8n Webhook

Route Odoo expense approvals automatically—via an n8n Webhook to Slack and Gmail

This n8n workflow accepts employee expense submissions through a webhook, creates the expense in Odoo, then sends a manager approval form in Slack. Once a decision is made, it updates the Odoo expense status and notifies the employee via Gmail.

What this workflow does

• Receives submissions with a POST webhook and normalizes key fields such as employee, vendor, amount, category, description, and receipt details.
• Validates input and returns a 400 JSON response when required data is missing or invalid.
• Checks employee records in Odoo using hr.employee; if no match is found, it returns a 404 JSON response.
• Creates the expense in Odoo by looking up the expense category in product.product and creating an hr.expense record. It responds with a 202 JSON payload containing the created expense ID.
• Sends a Slack approval request to the #expense-approvals channel using a custom approval form, waiting up to two days for a manager decision.
• Updates status and emails the employee via Gmail:
  • If approved: updates the Odoo expense state to approved and emails the employee.
  • If refused: marks it as refused with the manager comment and emails the employee to resubmit.

Use cases

• Centralize expense intake from employees into a single webhook endpoint.
• Reduce manual back-and-forth by sending approvals directly to a dedicated Slack channel.
• Automatically keep Odoo hr.expense records synchronized with manager decisions.

Technical details

• n8n webhook workflow with field normalization, validation, and JSON responses (400/404/202).
• Odoo integration via nodes for hr.employee, product.product, and hr.expense.
• Slack approval posting to #expense-approvals with a wait period for decisions.
• Gmail notifications to employees based on approval outcomes.
• Nodes used include: if, set, no op, odoo, gmail, and slack.