3. Defining the Resources

An ARM resource provider is composed of resources. The TypeSpec Azure Resource Manager library makes it much easier to define the structure and endpoints of such resources.

There are three essential components of a resource defined with TypeSpec:

• A model type representing the resource, derived from one of the base resource types
• A model type defining the properties of the resource type
• An interface that defines the operations that can be performed on the resource type, usually a combination of recommended and required Operations and resource actions

Read the TypeSpec tutorial to learn the basics about TypeSpec model types and interfaces.

1. Define a model representing the properties of the ARM resource

Each resource type must have a properties type which defines its custom properties. This type will be exposed as the properties property of the resource type.

/** The properties of User */
model UserProperties {
  /** The user's full name */
  fullName: string;

  /** The user's email address */
  emailAddress: string;
}

2. Define a model representing the resource type

Resource types are defined as plain models which pull in a standard resource type using the is keyword.

You define a resource type, you need the following:

• A property model type which defines the resource type’s custom properties as we described in step 1
• A name parameter definition. You should use ResourceNameParameter model which automatically populate the following decorators with camel cased name for @key and pluralized name for @segment as values. You can override these values via ResourceNameParameter’s optional template parameter.
  • @key: Specifies the parameter name for this resource type in the service URI hierarchy
  • @segment: Specifies the name of the resource “collection”, the URI segment that comes just before the parameter name which identifies the resource type

Here we define a tracked resource called User:

/** A User Resource */
model User is TrackedResource<UserProperties> {
  ...ResourceNameParameter<User>;
}

3. Define an interface with operations for the resource type

@armResourceOperations
interface Users {
  get is ArmResourceRead<User>;
  create is ArmResourceCreateOrReplaceAsync<User>;
  update is ArmCustomPatchSync<
    User,
    Azure.ResourceManager.Foundations.ResourceUpdateModel<User, UserProperties>
  >;
  delete is ArmResourceDeleteSync<User>;
  listByResourceGroup is ArmResourceListByParent<User>;
  listBySubscription is ArmListBySubscription<User>;
}

This uses operation templates defined in the Azure.ResourceManager namespace to define the operations over your resource. For operations like create (PUT), update (PATCH) and delete (DELETE) there are both asynchronous (long-running) and synchronous (operation completes in the same http request) versions of the operation templates.

The interface above creates the following operations for your service:

Method & Path	Description
GET /subscriptions/{subscriptionId}/providers/Contoso.Users/users	list all User by subscription
GET /subscriptions/{subscriptionId}/resourceGroups/{resourceGroupName}/providers/Contoso.Users/users	list all User by resource group
GET /subscriptions/{subscriptionId}/resourceGroups/{resourceGroupName}/providers/Contoso.Users/users/{userName}	get item
PUT /subscriptions/{subscriptionId}/resourceGroups/{resourceGroupName}/providers/Contoso.Users/users/{userName}	create item
PATCH /subscriptions/{subscriptionId}/resourceGroups/{resourceGroupName}/providers/Contoso.Users/users/{userName}	patch item
DELETE /subscriptions/{subscriptionId}/resourceGroups/{resourceGroupName}/providers/Contoso.Users/users/{userName}	delete item

Base Resource Types

Here are the base resource types you can use when defining your own ARM resources:

Name	Description
TrackedResource<TProperties>	Defines a normal ARM resource where TProperties is the model of the properties
ProxyResource<TProperties>	Defines a proxy ARM resource where TProperties is the model of the properties
ExtensionResource<TProperties>	Defines an extension ARM resource where TProperties is the model of the properties