Interpreting an API response

HTTP status code​

The HTTP status codes used by the ONTAP REST API are described below.

Response headers​

Several headers are included in the HTTP response generated by the ONTAP.

Location

When an object is created, the location header includes the complete URL to the new object including the unique identifier assigned to the object.

Content-type

This will normally be application/hal+json.

Response body​

The content of the response body resulting from an API request differs based on the object, processing type, and the success or failure of the request. The response is always rendered in JSON.

• Single object

  A single object can be returned with a set of fields based on the request. For example, you can use GET to retrieve selected properties of a cluster using the unique identifier.

• Multiple objects

  Multiple objects from a resource collection can be returned. In all cases, there is a consistent format used, with num_records indicating the number of records and records containing an array of the object instances. For example, you can retrieve the nodes defined in a specific cluster.

• Job object

  If an API call is processed asynchronously, a Job object is returned which anchors the background task. For example, the PATCH request used to update the cluster configuration is processed asynchronously and returns a Job object.

• Error object

  If an error occurs, an Error object is always returned. For example, you will receive an error when attempting to change a field not defined for a cluster.

• Empty

  In certain cases, no data is returned and the response body includes an empty JSON object.

HAL linking​

The ONTAP REST API uses HAL as the mechanism to support Hypermedia as the Engine of Application State (HATEOAS). When an object or attribute is returned that identifies a specific resource, a HAL-encoded link is also included allowing you to easily locate and determine additional details about the resource.

Errors​

If an error occurs, an error object is returned in the response body.

Format

An error object has the following format:

"error": {
   "message": "<string>",
   "code": <integer>[,
   "target": "<string>"]
}

You can use the code value to determine the general error type or category, and the message to determine the specific error. When available, the target field includes the specific user input associated with the error.

Common error codes

The common error codes are described in the following table. Specific API calls can include additional error codes.