I have problems on a simple design problem. I have many companies. Each company have one or more commercial activity. Activities types are: ecommerce, local unit, television, automatic vending machines, and so on. Company may have one or more ecommerce activity or one or more local unit activity, one ormore vending machines, etc. How can I model this scenario? Company has_many ecommerce has_many local_units has_many televisions and so on?
So can each Company have many CommercialActivities
Then… CommercialActivity is STI, which means it has a type column and sub-types can be ECommerceActivity, TelevisionActivity, etc…
The only warning is that if each type is dramatically different, you might want to investigate doing it with multiple tables so you dont have a lot of redundant fields trying model things with additional attributes that aren’t shared.
I think this post might help you http://stackoverflow.com/questions/1634668/multiple-table-inheritance-vs-single-table-inheritance-in-ruby-on-rails
I have problems on a simple design problem.
I have many companies. Each company have one or more commercial activity.
Activities types are: ecommerce, local unit, television, automatic
vending machines, and so on.
So can each Company have many CommercialActivities
Then… CommercialActivity is STI, which means it has a type column and sub-types can be ECommerceActivity, TelevisionActivity, etc…
The only warning is that if each type is dramatically different, you might want to investigate doing it with multiple tables so you dont have a lot of redundant fields trying model things with additional attributes that aren’t shared.
I think this post might help you http://stackoverflow.com/questions/1634668/multiple-table-inheritance-vs-single-table-inheritance-in-ruby-on-rails
You can also use a project of mine (Super STI) to help you. It helps you use STI in Rails while keeping your database clean. Read about it at https://github.com/ihid/super_sti and http://www.ihid.co.uk/projects/super_sti
Message me off-list if you want some help with using it.
Yes the problem is that television, ecommerce, etc. they don't share the same attributes.
I have problems on a simple design problem.
I have many companies. Each company have one or more commercial activity.
Activities types are: ecommerce, local unit, television, automatic
vending machines, and so on.
So can each Company have many CommercialActivities
Then… CommercialActivity is STI, which means it has a type column and
sub-types can be ECommerceActivity, TelevisionActivity, etc…
The only warning is that if each type is dramatically different, you might
want to investigate doing it with multiple tables so you dont have a lot of
redundant fields trying model things with additional attributes that aren’t
shared.
Yes the problem is that television, ecommerce, etc. they don’t share
the same attributes.
Use a polymorphic link table.
So tables:
companies: (name:string)
company_activities: (company_id:int, activity_id:int, activity_type:string)
television_activities(…)
ecommerce_activitiies(…)
Models:
class Company < ActiveRecord::Base
has_many :company_activities
has_many :activities, through: company_activities
end
class CompanyActivity < ActiveRecord::Base
belongs_to :company
belongs_to :activity, polymorphic:true end
and then lots of:
class TelevisionActivity < ActiveRecord::Base
has_many :company_activities
has_many :companies, through: company_activities
end
class EcommerceActivity < ActiveRecord::Base
has_many :company_activities
has_many :companies, through: company_activities
end
etc
Those could all inherit from Activity if you want to use STI, but they don’t need to.
Sorry for my ignorance, in your example have you forgot Activity model and activities table?
ok, sorry they don't need.
