What is the correct way to use nested entities in a REST response?

Question

Software design

Good afternoon. Can you please tell me how to properly use nested entities in a REST response?
For example:
There is a simple task creation service.
To create a task, make a POST request to the /rest/tasks endpoint

{
    "author_id": 2 
    "task": "blah blah"
}

Is it possible to also display a nested entity with a username? Is this the right approach?
for example:
/rest/tasks/1

{
    "id": 1,
    "author": {
        "id": 2,
        "username": "user"
     },
     "task": "blah blah"
}

If there are links to some additional sources/books on best practices, please indicate.

Answer 1

Do not use. To do this, either think about HAL / HATEOAS or towards GraphQL. REST works for this case, but fits very poorly into the concept

Answer 2

Yii2 implements the following built-in URL parser:
In the normal case, when requesting an endpoint, a flat json with data is returned back. The author will be a number (id). If you add ?expand=author to the URL, the engine will automatically query the database for information about the author and insert it as a subarray where the identifier was. Essno, there is a list of relays allowed / prohibited for deployment.
You can also close it like this: expand=affor,affor.comments, then, in addition to the author, there will be a third level of nesting, subarraying the author's last comments (by default in Yii2 this is 20, again configured both on the backend and perpage in the URL).