Create Secure Human-in-the-Loop Approval Flows with Postgres and Telegram

This n8n workflow simplifies the creation of secure human-in-the-loop (HITL) approval processes by integrating a webhook trigger, conditional logic, database interaction with PostgreSQL, and notifications via Telegram. It's designed to handle incoming requests, make decisions based on predefined conditions, record actions in a database, and communicate approvals or rejections to relevant stakeholders.

What it does

This workflow automates the following steps:

1. Receives Incoming Requests: It starts by listening for incoming HTTP requests via a Webhook. This serves as the entry point for new approval requests or actions.
2. Routes Based on Request Type: A Switch node then evaluates the incoming request to determine its type (e.g., new approval request, approval confirmation, rejection confirmation).
3. Applies Conditional Logic: An If node applies further conditional logic based on the request type, allowing for different processing paths.
4. Interacts with PostgreSQL: Depending on the logic, the workflow interacts with a PostgreSQL database to:
   • Store new approval requests.
   • Update the status of existing requests (e.g., approved, rejected).
   • Retrieve information about requests.
5. Sends Telegram Notifications: It sends messages to a Telegram chat, which can be used for:
   • Notifying approvers about new requests.
   • Confirming approval or rejection actions.
   • Providing links for approvers to take action (e.g., approve/reject buttons).
6. Executes Custom Code (Optional): A Code node is included, allowing for custom JavaScript logic to be executed at a specific point in the workflow, potentially for data transformation, validation, or complex calculations.
7. Provides Documentation/Notes: A Sticky Note node is present, likely for internal documentation or explanations within the workflow itself.

Prerequisites/Requirements

To use this workflow, you will need:

• n8n Instance: A running n8n instance.
• PostgreSQL Database: Access to a PostgreSQL database with appropriate credentials.
• Telegram Bot Token: A Telegram Bot Token and Chat ID for sending messages.
• Webhook Endpoint: An external system or application that can send HTTP requests to the n8n webhook.

Setup/Usage

1. Import the Workflow: Import the provided JSON into your n8n instance.
2. Configure Credentials:
   • Postgres: Set up your PostgreSQL credentials in n8n.
   • Telegram: Set up your Telegram Bot API credentials in n8n.
3. Configure Webhook:
   • Activate the Webhook node and copy its URL. This URL will be the endpoint for your incoming approval requests.
   • Ensure the webhook is configured to receive the expected JSON payload for your approval requests.
4. Configure Nodes:
   • Postgres Node: Configure the Postgres nodes with the specific SQL queries or operations required for your database schema (e.g., INSERT for new requests, UPDATE for status changes, SELECT for retrieval).
   • Telegram Node: Configure the Telegram nodes with the correct Chat ID and message content for notifications. You might use expressions to dynamically include request details in the messages.
   • Switch/If Nodes: Adjust the conditions in the Switch and If nodes to match your specific approval logic and incoming data structure.
   • Code Node: If custom logic is required, modify the Code node with your JavaScript.
5. Activate the Workflow: Once all configurations are complete, activate the workflow.

This workflow provides a robust foundation for building interactive approval systems, leveraging the power of n8n to connect databases and communication platforms.