I have an Activity model that will show a list of events that occurred (post created, event created, etc.).
In activity.rb, I have:
class Activity < ApplicationRecord
has_one :post
has_one :event
end
For my Activity migration file, I have it set up like so:
class CreateActivities < ActiveRecord::Migration[7.1]
def change
create_table :activities do |t|
t.string :action, null: false
t.string :action_model, null: false
t.string :action_model_id, null: false
t.timestamps
end
end
end
I’m using a generic action_model_id for reusability between different models (instead of needing to store a field for every association, for example: post_id, event_id, etc).
How can I call activity.post or activity.event while keeping this generic?
1
Models changes
class Activity < ApplicationRecord
belongs_to :action_model, polymorphic :true
end
class Post < ApplicationRecord
has_many :activities, as: :action_model
end
class Event < ApplicationRecord
has_many :activities, as: :action_model
end
And you need to change migration
class CreateActivities < ActiveRecord::Migration[7.1]
def change
create_table :activities do |t|
t.bigint :action_model_id, null: false
t.string :action_model_type, null: false
t.timestamps
end
add_index :activities, [:action_model_id, :action_model_type]
end
end
1