The OPTIONS method in a REST API is used to retrieve information about the communication options available for a resource.
It allows a client to discover the available methods and the communication options that the server supports, such as the supported HTTP methods, headers, and the format of the request and response.
A typical OPTIONS request will include the following:
- The HTTP verb “OPTIONS”.
- The endpoint or resource location, such as “/products”.
- The headers, which may include additional information such as the accept type or the authentication information.
- The request body is empty as it is not needed for an OPTIONS request.
A typical OPTIONS response will include the following:
- The HTTP status code, such as 200 OK if the request was successful or 403 Forbidden if the client is not authorized to access the requested resource.
- The headers, which may include additional information such as the Allow header which indicates which HTTP methods are supported by the resource, and the content type or caching directives.
- The response body is empty as it is not needed for an OPTIONS request.
It’s worth noting that the OPTIONS method is not widely used in REST APIs, but it’s considered a best practice to implement it to allow clients to discover the communication options available.
Additionally, it could be used as a cross-origin resource sharing (CORS) preflight check, which allows a client to retrieve information about the communication options without actually accessing the resource.