5. Defining standard resource operations

The Azure.Core namespace provides a variety of standard lifecycle operations for resource types. These operations adhere to the requirements of the Azure REST API Guidelines.

Operation interface definition

To define standard operations for a resource type, create an instance of the ResourceOperations interface that is tailored to your service. Here’s an example:

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

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

alias ServiceTraits = SupportsRepeatableRequests &
  SupportsConditionalRequests &
  SupportsClientRequestId;

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

In this example:

1. ServiceTraits is defined as the intersection of three trait model types available in Azure.Core. Learn more about interface-level service traits here.
2. Operations is defined as the instantiation of Azure.Core.ResourceOperations with the service trait types you defined.

Note: The name Operations is used for convenience, but you might define multiple aliases of ResourceOperation for a single service to apply different customizations for some operations. You might choose a more explicit name like StandardOperations.

Next, we’ll use this interface alias to define the standard resource operations we need.

Resource operations definition

We’ll define the standard set of CRUD (Create, Read, Update, Delete) operations typically needed for a resource type in an Azure service. We’ll do this by defining an interface called Widgets:

interface Widgets {
  /** Fetch a Widget by name. */
  getWidget is Operations.ResourceRead<Widget>;

  /** Creates or updates a Widget. */
  createOrUpdateWidget is Operations.ResourceCreateOrUpdate<Widget>;

  /** Delete a Widget. */
  deleteWidget is Operations.ResourceDelete<Widget>;

  /** List Widget resources. */
  listWidgets is Operations.ResourceList<Widget>;
}

Note: It’s not necessary to define your resource operations inside of an interface. You can also define them in a sub-namespace of your service or inside the top-level namespace of the service. However, it’s a best practice in TypeSpec to use interface to encapsulate the operations of a particular resource type.

The Widget interface defines the following standard lifecycle operations:

• ResourceRead<TResource>: Defines a “read” operation for a single resource instance.
• ResourceCreateOrUpdate<TResource>: Defines an “upsert” operation which either creates or updates an instance of the resource type depending on whether it already exists.
• ResourceDelete<TResource>: Defines a “delete” operation to delete a specific instance of the resource.
• ResourceList<TResource>: Defines an operation that lists all instances of the resource type.

Note: There are both instantaneous and long-running versions of “create”, “update”, and “delete” operations for resource types depending on what you need for a particular resource!

These operations will all exist under the route path /widgets/{widgetName}, with the list operation generating the path /widgets.

Error response customization

If your service needs to use a custom error response type for all resource operations (which is uncommon), you may pass in a custom error response type to the ResourceOperations interface:

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

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

alias ServiceTraits = SupportsRepeatableRequests &
  SupportsConditionalRequests &
  SupportsClientRequestId;

/** A custom error response type. */
@error
model ErrorResponse {
  /** The error code. */
  code: string;

  /** The error message. */
  message: string;
}

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

You can also reuse the standard Azure Core error types with minor customizations:

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

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

alias ServiceTraits = SupportsRepeatableRequests &
  SupportsConditionalRequests &
  SupportsClientRequestId;

/** A custom error type. */
model Error is Azure.Core.Foundations.Error {
  /** The environment where the error occurred. */
  environment: string;
}

alias Operations = Azure.Core.ResourceOperations<
  ServiceTraits,
  Azure.Core.Foundations.ErrorResponseBase<Error>
>;