1
I have the following configuration in Rails:
Company
 has_many :company_products
 has_many :products, :through => :company_products
Product
 has_many :company_products
 has_many :companies, :through => :company_products
Productgroup
 has_many :company_products
Companyproduct
 belongs_to :company
 belongs_to :product
 belongs_to :product_group
I need to validate every time I create the Company or Product contains a CompanyProduct also.
How can I validate CompanyProduct by the Company or Product ?