Is it correct to use singular names when there is a one-to-one mapping and how to design the REST URI?

Question

I was wondering when it is considered correct to use singular names in REST (I mean, using best practices), but more particularly when there is a one-to-one mapping between two entities.

First example, we have to manage loyalty for customers. A customer can access his profile with /me. Furthermore, he has a loyalty account that displays several information about loyalty points, discounts, next threshold to unlock a specific status. Would you design the path like:

• /me/fidelity_account,
• /me/fidelity_accounts/mine - my favourite,
• /me/my_fidelity_account,
• /me/my_fidelity_accounts/mine,
• /me/fidelity_accounts/{id}, assuming that giving the wrong id gives a 403,
• or any other way to design that?

Second example, we have to manage shopping lists for customers. A customer may have several lists, but must have at least always a list called "Internet Shopping List". This list is unique, amongst other lists having their own ID. The internet shopping list has a totally different schema.

We have several ideas about this use case:

1. Create totally different paths, such as /me/shopping_lists/{id}, but /me/internet_shopping_list (singular) for the specific list. It's my best bet.
2. Create same paths, such as /me/shopping_lists/{id}, but /me/shopping_lists/internet_shopping_list for the specific list.
3. Or maybe another way?

Answer 1

I kept thinking about this question and a few answers came out to be better than others. Assuming that the user has provided a token to identify himself: - /me/fidelity_accounts/mine - mine here would be an alias for the id. - /me/fidelity_accounts/{id} - thus, {id} must work only if the id of the account is relevant with the token the user has given. - /me/fidelity_account - it's not restful, but it's the simplest way