REST api design to retrieve summary information

Question

I have a scenario in which I have REST API which manages a Resource which we will call Group. A Group is similar in concept to a discussion forum in Google Groups.

Now I have two GET access method which I believe needs separate representations.

The 1st GET access method retrieves the minimal amount of information about a Group. Given a group_id it should return a minimal amount of information like

{ 
    group_id: "5t7yu8i9io0op",
    group_name: "Android Developers",
    is_moderated: true,
    number_of_users: 34,
    new_messages: 5,
    icon: "http://boo.com/pic.png"
}

The 2nd GET access method retrives summary information which are more statistical in nature like:

{ 
    group_id: "5t7yu8i9io0op",
    top_ranking_users: {
      [ { user: "george", posts: 789, rank: 1 }, 
        { user: "joel", posts: 560, rank: 2 }  ...]
    },
    popular_topics: {
      [ ... ]
    }
}

I want to separate these data access methods and I'm currently planning on this design:

GET /group/:group_id/
GET /group/:group_id/stat

Only the latter will return the statistical information about the group. What do you think about this ?

Answer 1

I don't see a problem with your approach. Since the statistics are basically separate data, you could treat the stats as a separate resource, too, providing a URI like

GET /stat/:group_id

Additionally you can cross reference your resources (meaning a group links to the corresponding stat resource and vice versa):

GET /group/5t7yu8i9io0op

{ 
    group_id: "5t7yu8i9io0op",
    group_name: "Android Developers",
    is_moderated: true,
    number_of_users: 34,
    new_messages: 5,
    icon: "http://boo.com/pic.png",
    stats: "http://mydomain.com/stat/5t7yu8i9io0op"
}

GET /stat/5t7yu8i9io0op

{ 
    group: "http://mydomain.com/group/5t7yu8i9io0op",
    top_ranking_users: {
      [ { user: "george", posts: 789, rank: 1 }, 
        { user: "joel", posts: 560, rank: 2 }  ...]
    },
    popular_topics: {
      [ ... ]
    }
}

Answer 2

What would be even better would be if you embedded the link to the statistics in the group summary:

{ 
    group_id: "5t7yu8i9io0op",
    group_name: "Android Developers",
    is_moderated: true,
    number_of_users: 34,
    new_messages: 5,
    icon: "http://boo.com/pic.png"
    stats_link : "http://whatever.who/cares"
}