Alright, let's start by setting up different versions of your API endpoints in Xano. Think of it like having /v1/users for Version 1 and /v2/users for Version 2. Each version can have its own unique logic or data structures, depending on what you need.

Next, head over to the "Middleware" section in Xano and create a new middleware. This middleware will check the incoming request and figure out which version of the API to use.

Here's the plan:

• Look at the Accept-Version header or any custom header you use to specify the API version.
• Based on that header, route the request to the right API endpoint.

Here's a sample middleware setup:

{
  "meta": {
    "name": "Version Negotiation",
    "slug": "version-negotiation"
  },
  "steps": [
    {
      "type": "condition",
      "condition": "request.header['Accept-Version'] === '1.0'",
      "then": {
        "type": "error.terminate",
        "status_code": 301,
        "response": {
          "Location": "/v1/users"
        }
      }
    },
    {
      "type": "condition",
      "condition": "request.header['Accept-Version'] === '2.0'",
      "then": {
        "type": "error.terminate",
        "status_code": 301,
        "response": {
          "Location": "/v2/users"
        }
      }
    },
    {
      "type": "default",
      "do": {
        "type": "error.terminate",
        "status_code": 400,
        "response": {
          "message": "Unsupported API version"
        }
      }
    }
  ]
}

Now, let's attach this middleware to the endpoints that need version negotiation. Usually, this would be your root or base endpoint, like /users. This way, any request to this endpoint will trigger the middleware logic and redirect to the correct versioned endpoint.

1. Go to the desired endpoint.
2. Click on the "Middleware" tab.
3. Add the "Version Negotiation" middleware to the endpoint.

Time to test! Make requests to your API, specifying the Accept-Version header:

• A request with the header Accept-Version: 1.0 should redirect to /v1/users.
• A request with the header Accept-Version: 2.0 should redirect to /v2/users.

Check to make sure the API response is what you expect for each version.

Finally, let's handle cases where the version header is missing or invalid. You might want to default to the latest version or return an error message. Adjust the middleware accordingly.

Here's an example:

{
  "meta": {
    "name": "Version Negotiation",
    "slug": "version-negotiation"
  },
  "steps": [
    {
      "type": "condition",
      "condition": "request.header['Accept-Version'] === '1.0'",
      "then": {
        "type": "error.terminate",
        "status_code": 301,
        "response": {
          "Location": "/v1/users"
        }
      }
    },
    {
      "type": "condition",
      "condition": "request.header['Accept-Version'] === '2.0'",
      "then": {
        "type": "error.terminate",
        "status_code": 301,
        "response": {
          "Location": "/v2/users"
        }
      }
    },
    {
      "type": "default",
      "do": {
        "type": "error.terminate",
        "status_code": 301,
        "response": {
          "Location": "/v2/users"
        }
      }
    }
  ]
}

This setup assumes that if the version header is missing, the request will be redirected to the latest version.

Follow these steps to implement API version negotiation smoothly in Xano, ensuring backward compatibility and flexibility.