"Right" REST URL to get all resources within all resources?

Question

So... I am aware that this question could be dangerously close to being opinion based . I'm hoping is not, and that the REST standard is clear about what I'm going to ask but if it's not, I'll close it.

I have a website (in Django, with the data being stored in Postgres) with Product(-s) and Category(-ies) Each category can contain several product(-s).

So, the question is: What would be the "right" endpoint (if there's any) to GET all the categories with all the products in each?

I believe it would be clear getting all the products of a specific category. For instance, if the category ID was 24, in order to get all its products, I would write:

http://myserver.com/api/categories/24/products

But how about ALL the categories with ALL the products in each?

Would it be http://myserver.com/api/categories/products?

Would it be http://myserver.com/api/categories/all/products?

Would it be better using some kind of parameter, such as http://myserver.com/api/categories?mode=all_products ?

The idea would be having a response like this (JSON format)

{
    "25": [{
        "id": 1,
        "name": "Product 1 in category 25",
        "price": 100
    }, {
        "id": 2,
        "name": "Product 2 in category 25",
        "price": 200
    }],
    "26": [{
        "id": 3,
        "name": "Product 1 in category 26",
        "price": 300
    }, {
        "id": 4,
        "name": "Product 2 in category 26",
        "price": 400
    }]
}

Thank you in advance.

Answer 1

As far as REST is concerned if you are uniquely representing the resource in the url so that it is cacheable (and abiding with HATEOAS but let's skip that part), it doesn't really matter how you structure your urls. With that said in my opinion, since you want to get all the products, your url should be something like

GET /products         # to return all products with their associated categories
GET /category/24/products  # to return all products belonging to a particular category

Note:- Although url structure is not exactly a part of REST, but designing url in terms of an entity/resource and an identifier does makes it easier to create RESTful APIs. Well structured urls also makes them easier to be consumed by clients.