Read/seen ranking

When track_read or track_seen is enabled on a feed group, you can use is_read and is_seen as variables in ranking expressions. On flat content feeds, enable them with activity_marks; notification feeds use their notification configuration. On content feeds, the ranking expression may only reference is_read or is_seen when the matching activity_marks.track_read or activity_marks.track_seen is enabled, otherwise creating or updating the feed group fails with ranking by read/seen status requires notification config or matching activity_marks tracking. Notification feeds can always rank by is_read and is_seen.

A mark only applies to activities created at or before the time it was set. On aggregated notification feeds, a group that is updated after it was marked counts as unread or unseen again.

For example, a custom flat feed group that sorts by popularity and subtracts 100 points from activities the user has read:

response, err := client.Feeds().CreateFeedGroup(ctx, &getstream.CreateFeedGroupRequest{
  ID: "ranked_timeline",
  ActivityMarks: &getstream.ActivityMarksConfig{
    TrackSeen: getstream.PtrTo(true),
    TrackRead: getstream.PtrTo(true),
  },
  ActivitySelectors: getstream.PtrTo([]getstream.ActivitySelectorConfig{
    {Type: getstream.PtrTo("following")},
  }),
  Ranking: &getstream.RankingConfig{
    Type:  getstream.PtrTo("expression"),
    Score: getstream.PtrTo("popularity - (is_read ? 100 : 0)"),
  },
})

To rank unseen activities first instead (this does not include popularity):

response, err := client.Feeds().CreateFeedGroup(ctx, &getstream.CreateFeedGroupRequest{
  ID: "unseen_timeline",
  ActivityMarks: &getstream.ActivityMarksConfig{
    TrackSeen: getstream.PtrTo(true),
    TrackRead: getstream.PtrTo(true),
  },
  ActivitySelectors: getstream.PtrTo([]getstream.ActivitySelectorConfig{
    {Type: getstream.PtrTo("following")},
  }),
  Ranking: &getstream.RankingConfig{
    Type:  getstream.PtrTo("expression"),
    Score: getstream.PtrTo("is_seen ? 0 : 100"),
  },
})

The same expressions work on notification feeds, where marks may be resolved per activity or aggregated group.

Example expressions

Aggregated feeds

On aggregated notification feeds, is_read and is_seen are resolved at the group level. All activities within an aggregated group share the same read/seen status. On flat feeds (content feeds with activity_marks, and flat notification feeds), they are resolved per activity. Content feeds with aggregation can't use activity_marks, so they can't rank by read/seen status.