Advanced Topics

Once you have written your first service with Azure.Core, you might be interested to try the following features:

Defining singleton resources

You can define a singleton resource (a resource type with only one instance) by using a string literal for the key type. Imagine we want to expose an analytics endpoint for each Widget instance. Here’s what it would look like:

@resource("analytics")
@parentResource(Widget)
model WidgetAnalytics {
  @key("analyticsId")
  id: "current";

  /** The number of uses of the widget. */
  useCount: int64;

  /** The number of times the widget was repaired. */
  repairCount: int64;
}

You can then use the standard operation signatures with this singleton resource type:

import "@azure-tools/typespec-azure-core";

using Azure.Core;
using Azure.Core.Traits;

alias ServiceTraits = SupportsRepeatableRequests &
  SupportsConditionalRequests &
  SupportsClientRequestId;

alias Operations = Azure.Core.ResourceOperations<ServiceTraits>;

op getAnalytics is Operations.ResourceRead<WidgetAnalytics>;
op updateAnalytics is Operations.ResourceCreateOrUpdate<WidgetAnalytics>;

By using a literal value of "current" for "id", the route path for these operations will be the following:

"/widgets/{widgetName}/analytics/current"

The operations defined against this singleton resource will also exclude the key parameter because it cannot be changed.