Question on Active Record select and join

I'm learning how to use ActiveRecord. To work with an existing dataase
I created the following classes

class Product < ActiveRecord::Base
  set_primary_key("ProductID")
  set_table_name("Product")
  has_many :variants, :foreign_key => 'ProductID'
  has_and_belongs_to_many :category, :foreign_key => 'ProductID',
:join_table =>'ProductCategory', :association_foreign_key
=>'CategoryID'
end

class Category < ActiveRecord::Base
  set_primary_key("CategoryID")
  set_table_name("Category")
  has_and_belongs_to_many :product, :foreign_key =>'CategoryID',
:join_table =>'ProductCategory', :association_foreign_key =>'ProductID'
end

class Variant < ActiveRecord::Base
  set_primary_key("VariantID")
  set_table_name("ProductVariant")
  #Foreign keys in table ProductVariant
  belongs_to :product, :foreign_key => 'ProductID'
  belongs_to :capacity, :foreign_key => 'CapacityID'
  belongs_to :material, :foreign_key => 'MaterialID'
end

class Capacity < ActiveRecord::Base
  set_primary_key("CapacityID")
  has_many :variants, :foreign_key => 'CapacityID'
end

class Material < ActiveRecord::Base
  set_primary_key("MaterialID")
  has_many :variants, :foreign_key => 'MaterialID'
end

I am trying to create the following SQL query using ActiveRecord
SELECT ProductVariant.Name, ProductVariant.Inventory,
ProductVariant.Price, Capacities.Name AS CapName, Materials.Name AS
MatName

FROM ProductVariant INNER JOIN Product ON ProductVariant.ProductID =
Product.ProductID INNER JOIN Materials ON ProductVariant.MaterialID =
Materials.MaterialID INNER JOIN Capacities ON ProductVariant.CapacityID
= Capacities.CapacityId

WHERE Product.ProductID = 17

I tried the following ActiveRecord code
widget=Product.find(17)
widget.variants.find(:all, :select =>'ProductVariant.Name, Inventory,
Price, Capacities.Name, Materials.Name', :include=> [:capacity,
:material] ).each do |v|

puts v.Name.squeeze(" ").chop! + "\t\t In stock: \t" +
v.Inventory.to_s + "\tPrice: \t" + v.Price.to_s + "\tCapacity: \t" +
v.capacity.Name.to_s + "\t Material: \t" + v.material.Name.to_s

end

but ActiveRecord is still selecting all the ProductVariant fields
instead of just the ones listed in the select paramater

I also tried
widget.variants.find(:all, :select =>'ProductVariant.Name,Inventory,
Price,Capacities.Name as CapName,Materials.Name as MatName',
:joins=>'ProductVariant INNER JOIN Product ON ProductVariant.ProductID
= Product.ProductID INNER JOIN Materials ON ProductVariant.MaterialID
= Materials.MaterialID INNER JOIN Capacities ON
ProductVariant.CapacityID = Capacities.CapacityId').each do |v|

but just got errors.

Any ideas would be greatly appreciated.

thanks

Luis

Check out your log/development.log, it will show you the queries that
are actually getting executed.

I'm thinking that this is the way ActiveRecord is designed. When it
retrieves a record object, it will only retireve a complete one. It
doesn't make sense to grab an object and only populate half of it's
fields.