Convert Complex SQL to Activerecord - ruby-on-rails

Question

Hi I am trying to work out if its possible to convert this SQL statement to something I can use within a controller on my rails project
SELECT "products".name, properties.display_name,variant_properties.description, variants.price FROM "products"
INNER JOIN "product_properties" ON "product_properties"."product_id" = "products"."id"
INNER JOIN variant_properties on product_properties.property_id = variant_properties.property_id
INNER JOIN "properties" ON "properties"."id" = "product_properties"."property_id" AND properties.id = variant_properties.property_id
INNER JOIN variants on variants.product_id = products.id AND variants.id = variant_properties.variant_id
GROUP BY products.name, variant_properties.description, properties.display_name, variants.price
ORDER BY 1,2,4,3

Answer 1

The simplest way to do it is cheat with the active record join method that accepts raw SQL:
products = Product.select("products.name, properties.display_name, variant_properties.description, variants.price")
.joins("INNER JOIN product_properties ON product_properties.product_id = products.id")
.joins("INNER JOIN variant_properties on product_properties.property_id = variant_properties.property_id")
.joins("INNER JOIN properties ON properties.id = product_properties.property_id AND properties.id = variant_properties.property_id")
.joins("INNER JOIN variants on variants.product_id = products.id AND variants.id = variant_properties.variant_id")
.group("products.name, variant_properties.description, properties.display_name, variants.price")
.order("products.name, properties.display_name, variants.price, variant_properties.description")
With proper associations in your models, you can simplify it to:
products = Product.select("products.name, properties.display_name, variant_properties.description, variants.price")
.joins(:product_properties)
.joins(:variant_properties)
.joins(:properties)
.joins(:variants)
.group("products.name, variant_properties.description, properties.display_name, variants.price")
.order("products.name, properties.display_name, variants.price, variant_properties.description")

Answer 2

Assume you have models:
class Product
has_many :product_properties
has_many :variants
has_many :properties, through: :product_properties
LIST = 'products.name, variant_properties.description, properties.display_name, variants.price'
scope :spec, -> {
joins(:product_properties, :properties, :variants).
merge(Property.strikt).
merge(Variant.strikt).
select(LIST).
group(LIST).
order('1,2,3,4')
}
end
class ProductProperty
belongs_to :product
belongs_to :property
end
class VariantProperty
belongs_to :variant
belongs_to :property
has_many :product_properties, foreign_key: :property_id, primary_key: :property_id
end
class Property
has_many :variant_properties
has_many :product_properties
scope :strikt, -> { joins(:variant_properties).joins(:product_properties) }
end
class Variant
belongs_to :product
has_many :variant_properties
scope :strikt, -> { joins(:product).joins(:variant_properties) }
end
so your SQL you should get as of:
Product.spec.to_sql