Convert a complex PostgreSQL query to Ruby - sql

Question

I'm new here and have some difficult to convert a complex Postgres query to Ruby. Here is the query:
SELECT date_part('year', p.created_at) AS anio,
date_part('month'::text, p.created_at) AS mes,
p.id_pais, pa.nombre AS nombre_pais,
pr.id_region, re.nombre AS nombre_region,
co.id_provincia, pr.nombre AS nombre_provincia,
p.id_comuna, co.nombre AS nombre_comuna,
p.id_tipo_propiedad, p.id_modalidad,
count(*) AS total_propiedades,
sum((p.precio/mo.conversion_dolar)/p.dimension_propiedad) AS suma_precio_m2_dolar,
sum((p.precio/mo.conversion_dolar)/p.dimension_propiedad)/count(*) AS promedio_precio_m2_dolar
FROM propiedad AS p
INNER JOIN monedas AS mo ON (p.id_moneda = mo.id)
INNER JOIN comuna AS co ON (p.id_comuna = co.id)
INNER JOIN provincia AS pr ON (co.id_provincia = pr.id)
INNER JOIN region AS re ON (pr.id_region = re.id)
INNER JOIN pais AS pa ON (p.id_pais = pa.id)
WHERE p.id_modalidad IS NOT NULL
AND p.created_at IS NOT NULL
AND p.precio > 1
AND p.dimension_propiedad > 1
GROUP BY date_part('year',p.created_at), date_part('month'::text, p.created_at), p.id_tipo_propiedad,
p.id_modalidad, p.id_pais, pr.id_region, co.id_provincia, p.id_comuna, pa.nombre, re.nombre, pr.nombre, co.nombre
If you can help me with this i'll appreciate it.

Answer 1

I'd just leave something like that as plain SQL and hand it to select_rows:
connection.select_rows(%q{
-- your big pile of SQL goes here
}).each do |row|
# row will be an array of Strings in here
end
You'll have to unstringify things yourself but that shouldn't be terribly difficult. You could also use execute:
rows = connection.execute(%q{
-- SQL goes here...
})
rows.each do |row|
# row will be a hash
end
Your query is pulling a bunch of data out of the database that doesn't correspond to any particular model so there's not much point in trying to get ActiveRecord to produce that SQL. If the query was producing a model, then you'd use Model.find_by_sql (and still avoid trying to convince ActiveRecord to produce the SQL you're after).