What is the correct implementation pattern for adding a custom REST API field to an existing endpoint using `register_rest_field()`?

Question

WordPress Expert — Medium

What is the correct implementation pattern for adding a custom REST API field to an existing endpoint using `register_rest_field()`?

Accepted Answer

The correct implementation pattern for adding a custom REST API field to an existing endpoint using `register_rest_field()` is to call it on the rest_api_init hook. This allows you to provide the necessary parameters such as object type, field name, callbacks for reading and writing, and schema for documentation and validation.