.NET / C# integration

When to call the API

Call the API from your ASP.NET controller or service layer before confirming the order. Never expose the API key or route the call through the client.

Code example

// .NET / C# — server-side, inject via IHttpClientFactory
var payload = new {
  destinationPostcode = postcode,
  basketValueCents = basketCents,
};
var response = await httpClient.PostAsJsonAsync(
  "https://api.deliveryzone.fi/api/v1/delivery/check",
  payload
);
var result = await response.Content.ReadFromJsonAsync<DeliveryCheckResult>();
if (!result.CanDeliver) {
  // Reject order: result.ReasonCode
}

Error handling

When canDeliver is false (or null), the response includes a reasonCode field. Display this to the customer:

• NOT_DELIVERABLE — postcode is outside your delivery zones, or not recognised (the API intentionally uses one generic code for both, to protect zone boundaries)
• MINIMUM_ORDER_NOT_MET — basket value is below the zone's minimum order
• BASKET_VALUE_REQUIRED — a basket value is needed to evaluate this destination's minimum-order or free-delivery rule

Always handle HTTP errors (5xx, timeout) gracefully. If the API is unreachable, fail safe — either reject the order or allow manual review.

Implementation checklist

• Inject HttpClient via dependency injection (IHttpClientFactory)
• Store API key in environment variables or user secrets
• Handle HTTP errors and timeouts with try/catch
• Test against a non-production delivery zone first
• Confirm rejection behaviour in your staging environment

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