api

REST API Example

This example demonstrates how to wrap the go-rules-engine in a simple REST API using the Go standard library (net/http).

Why a REST API?

While the engine is primarily a library, exposing it as a service allows for:

• Centralized Rules: One service calculating rules for multiple clients.
• Cross-language Support: Non-Go services can evaluate rules via JSON over HTTP.
• Stateless Evaluation: Facts are sent in the request, results are returned in the response.

Features of this Example

1. Stateless Handlers: Every request creates a fresh Almanac.
2. Smart Skip Integration: Rules are automatically skipped if required facts are missing from the request, preventing evaluation errors.
3. Audit Trace: The response includes the full evaluation path (if enabled).
4. Execution Headers: Returns X-Execution-Time in response headers.
5. Error Handling: Proper JSON error responses for malformed inputs.

How to run

go run docs/examples/api/main.go

How to test

Open another terminal and use curl to send facts:

curl -X POST http://localhost:8080/evaluate \
  -H "Content-Type: application/json" \
  -d '{
    "facts": {
      "totalSpend": 1200,
      "accountAgeDays": 400,
      "amount": 100,
      "isFirstPurchase": false
    }
  }'

The output will be a JSON object containing the results for all evaluated rules.