esdiscuss-query.js

function getPage(page, numberPerPage) {
  numberPerPage = numberPerPage || 20;
  return db.messages.aggregate(
    { '$sort': { date: 1 } },
    {
      '$group': {
        _id: "$subjectID",
        subject: { '$first': '$subject'},
        messages: {'$sum': 1},
        first: { '$first': '$from' },
        last: { '$last': '$from' },
        start: { '$first': '$date' },
        end: { '$last': '$date' }
      }
    },
    { '$sort': {start: -1} },
    { '$skip': page * numberPerPage },
    { '$limit' : numberPerPage });
}

function totalNumberOfTopics() {
  return db.messages.aggregate({'$sort': { date: 1 }}, {
    '$group': {
      _id: "$subjectID",
      subject: { '$first': '$subject'},
      messages: {'$sum': 1},
      first: { '$first': '$from' },
      last: { '$last': '$from' },
      start: { '$first': '$date' },
      end: { '$last': '$date' }
    }}, {'$group': {_id: '1', 'count': {'$sum': 1}}});
}