Rails: Many-to-many Polymorphic Associations: Getting specific Type of Records
I have the following classes:
class Region < ActiveRecord::Base
has_many :geographical_relations, :as => :contained
has_many :geographical_units, :as => :container, :class_name => "GeographicalRelation"
end
class GeographicalRelation < ActiveRecord::Base
belongs_to :container, :polymorphic => true
belongs_to :contained, :polymorphic => true
end
class Country < ActiveRecord::Base
has_many :geographical_relations, :as => :contained
end
And I want to be able to, from a Country record, get all the Regions in which it is contained:
c = Country.find(1)
c.regions #=> should return all the regions in which c is cont开发者_高级运维ained
For now I've created the following method:
def regions
self.geographical_relations.where(:container_type => "Region").map{|relation| relation.container}
end
But I wonder if there's any way to set an "has_many" association to do this for me.
Cheers.
EDIT:
after trying the alternatives suggested in the comments I only got nice ActiveRecord errors.
The has_many_polymorphs gem seems to be a good way to do this, but for Rails 3 it is not 'officially' supported so for my case it is not a good option.
So I will work with methods like the one described above, putting them in modules and including the respective modules inside each "container"/"contained" models. This seems to work ok. =) Only change I made, to avoid N+1 Queries was adding 'includes':
def regions
self.geographical_relations.includes(:container).where(:container_type => "Region").map{|relation| relation.container}
end
Hopefully this works nicely and fast... =P =)
Anyway if anyone has an answer to solve this I'll look forward to see it! =)
Thanks all!
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