External prices

How to manage prices via external services

Sometimes, you can decide not to manage prices within Commerce Layer but use an external service instead. You may want to do that in order to support more dynamic pricing or just leverage an existing service that you want to keep as your system of records.

If you want to use the external prices feature in a market, fill in the market's external_prices_url field with your external service endpoint and make sure your service is compliant with the specifications described below.

Fetching external prices

When you add a line item to an order, set the _external_price attribute to true if you want the line item price to be provided by your external service, instead of Commerce Layer:

curl -g -X POST \
  'https://yourdomain.commercelayer.io/api/line_items' \
  -H 'Accept: application/vnd.api+json' \
  -H 'Authorization: Bearer your-access-token' \
  -H 'Content-Type: application/vnd.api+json' \
  -d '{
    "data": {
      "type": "line_items",
      "attributes": {
        "quantity": 2,
        "sku_code": "TSHIRTMM000000FFFFFFXLXX",
        "_external_price": true
      },
      "relationships": {
        "order": {
         "data": {
            "type": "orders",
            "id": "QWERtyUpBa"
          }
        }
      }
    }
  }'

Upon line item creation, Commerce Layer triggers a POST request to the specified external_prices_url endpoint, sending the line item payload (including the order) in the request body.

Once the external price trigger is set for a line item, any following computation on that line item's price will be performed invoking your external endpoint. If, for some reason, you want to stop using the external service for the price computation and use the price from the market price list (or price tier), you just need to PATCH the line item setting the _external_price trigger attribute to false.

Request

The request payload is a JSON:API-compliant object you can query to perform your own computation. Aside from the target resource — line_items in this specific case — some relationships are also included to avoid useless API roundtrips:

• order

• order.customer

• order.customer.tags

• order.line_items

• order.market

• item

{
  "data": {
    "id": "xYZkjABcde",
    "type": "line_items",
    "links": { ... },
    "attributes": {
      "quantity": 2,
      "sku_code": "TSHIRTMM000000FFFFFFXLXX",
      "_external_price": true
    },
    "relationships": { ... },
    "meta": { ... }
  },
  "included": [
    {
      "id": "wBXVhKzrnq",
      "type": "orders",
      "links": { ... },
      "attributes": { ... },
      "relationships": { ... },
      "meta": { ... }
    },
    {
      "id": "bGvCXzYgNB",
      "type": "customers",
      "links": { ... },
      "attributes": { ... },
      "relationships": { ... },
      "meta": { ... }
    },
    {
      "id": "YawgnfmKad",
      "type": "tags",
      "links": { ... },
      "attributes": { ... },
      "relationships": { ... },
      "meta": { ... }
    },
    {
      "id": "hJnnKTGfRd",
      "type": "line_items",
      "links": { ... },
      "attributes": { ... },
      "relationships": { ... },
      "meta": { ... }
    },
    {
      "id": "DvlGRmhdgX",
      "type": "markets",
      "links": { ... },
      "attributes": { ... },
      "relationships": { ... },
      "meta": { ... }
    },
    {
      "id": "XGZwpOSrWL",
      "type": "skus",
      "links": { ... },
      "attributes": { ... },
      "relationships": { ... },
      "meta": { ... }
    }
  ]
}

In case the call to your external endpoint goes timeout, responds with an internal server error, or is blocked by the open circuit breaker, the API responds with a 422 status code by using the response error message. The circuit breaker internal counter (if closed) is incremented.

Response

Your service response (or error) must match the format described in the example below.

Example

Response

The successful response must be a JSON object, returning at least the unit price computed by the external logic and the SKU code of the related product. If needed, you can optionally enrich the response with some additional information, notification messages, and metadata:

{
  "success": true,
  "data": {
    "sku_code": "TSHIRTMM000000FFFFFFXLXX",
    "unit_amount_cents": 4900,
    "messages": [ ... ],
    "metadata": {
      "foo": "bar"
    }
  }
}

Error

On error, you must respond with an HTTP code >= 400. The response body must be a JSON object containing any other relevant error code and message:

{
  "success": false,
  "error": {
    "code": "YOUR-ERROR-CODE",
    "message": "Your error message"
  }
}

If needed, you can specify in the response also the compare_at_amount_cents of the price, which should be greater than the unit_amount_cents. If not (i.e. if it's not specified or lower than the unit amount) it will be automatically set as equal to the unit_amount_cents.

If you specify the messages key a notification with the related information is automatically attached to the patched line item.

SKUs availability

When you fetch a list of SKUs with a sales channel, you only get those SKUs that have a price defined in the market's price list and at least a stock item in one of the market stock locations.

In case you manage prices externally, the price filter is not considered.

Security

When you activate external prices, a shared secret is generated at the market level. We recommend verifying the callback authenticity by signing the payload with that shared secret and comparing the result with the callback signature header.

Callbacks security