Use the ORM to get most recent affiliation and his assets for each politician

[giovanisleite]

Solve these TODO#load_affiliations and TODO#load_assets

perfil-politico/perfil/core/management/commands/load_affiliations.py

Lines 43 to 59 in 2d18841

	def politicians_from_affiliation():
	# TODO use the ORM (get most recent affiliation for each `voter_id`)
	sql = """
	SELECT core_affiliation.*
	FROM core_affiliation
	INNER JOIN (
	SELECT voter_id, MAX(started_in) AS started_in
	FROM core_affiliation
	GROUP BY voter_id
	) AS most_recent
	ON most_recent.voter_id = core_affiliation.voter_id
	WHERE status = 'R';
	"""
	yield from (
	Politician(current_affiliation=affiliation)
	for affiliation in Affiliation.objects.raw(sql).iterator()
	)

perfil-politico/perfil/core/management/commands/load_assets.py

Lines 50 to 65 in 88ad9b7

	@staticmethod
	def assets_per_politician_per_year():
	# TODO use the ORM?
	Row = namedtuple("Row", ("politician_id", "year", "value"))
	sql = """
	SELECT
	core_candidate.politician_id,
	core_candidate.year,
	SUM(core_asset.value) AS total
	FROM core_asset
	INNER JOIN core_candidate
	ON core_candidate.id = core_asset.candidate_id
	WHERE core_candidate.politician_id IS NOT NULL
	GROUP BY core_candidate.politician_id, core_candidate.year
	ORDER BY core_candidate.year DESC
	"""

Is it possible to use the ORM in these cases? Will the change turn it more readable?