REST API Designs with categories

Question

Let's say there is a SINGLE mobile application which receives various types of notifications (like WhatsApp notifications, Facebook Messenger notifications ,etc). What would be a better REST API structure for this?

/users/[email protected]/notifications //Gives all the notifications

There is a confusion between the below two formats on how .

/users/[email protected]/notifications?category=whatsapp,facebook    //Gives all the notifications

vs

/users/[email protected]/notifications/whatsapp  //Gives only whatsapp notification
/users/[email protected]/notifications/facebook  //Gives only facebook notification

To access an individual notification resource

/users/[email protected]/notifications/facebook/{notification-id}

vs

/users/[email protected]/notifications/{notification-id}

Answer 1

If a resource has a unique ID then it should be directly accessible from that, so in my opinion

/notifications/{id}

Would make most sense. In terms of filtering, this is probably more about preference than anything. Here's what I think would be the most idiomatic approach

/notifications    // fetch all notifications
/notifications/facebook    // fetch all Facebook messages
/notifications/whatsapp    // fetch all WhatsApp messages
/users/{id}/notifications    // fetch user notifications 
/users/{id}/notifications/facebook    // fetch user Facebook notifications 
/users/{id}/notifications/whatsapp    // fetch user WhatsApp messages