Fluff is a library that works with pillowtop and couchdbkit and lets you define a set of computations to do on all docs of a doc_type, i.e. perform a map over them, and then use couchdb to aggregate over the output.

The advantages of this over a normal map reduce are that you get to write your map in python with full access to the database.

This document describes the intended capabilities; what's currently here is very preliminary.

Example:

import fluff

class VisitCalculator(fluff.Calculator):

    @fluff.date_emitter
    def all_visits(self, case):
        for action in case.actions:
            yield action.date

    @fluff.date_emitter
    def bp_visits(self, case):
        for action in case.actions:
            if is_bp(case):
                yield action.date


class MyIndicators(fluff.IndicatorDocument):
    document_class = CommCareCase
    group_by = ('domain', 'owner_id')
    domains = ('droberts', 'test', 'corpora')

    visits_week = VisitCalculator(window=timedelta(days=7))
    visits_month = VisitCalculator(window=timedelta(days=30))


# add this pillow to settings.PILLOWTOPS
MyIndicatorsPillow = MyIndicators.pillow()

By creating a simple setup of this sort, you'll get a bunch of stuff for free:

• Whenever a doc changes, the corresponding indicator document will be updated

• You can get aggregated results back straight from couch with a simple MyIndicators.get_result('visits_week', key=[domain, owner_id]), which will be correct for the current date/time with no real-time computation, and will return the data in the following format:

  {
      "all_visits": 26,
      "bp_visits": 15
  }