I'm a rails newb and have been Googling about this, but I'm still stumped.
Not showing everything here, but basically it should be a pretty common
setup so I'm sure others know what I'm doing wrong.
- A meter can belong to many meter_groups
- A meter_group can have many meters.
- A user can 'subscribe' to viewing a meter_group (Subscription) so he
should be able to see the meters that are in that meter_group of the
subscription (think subscribing to a topic in a forum.)
Initially I was only allowing a single meter to belong to only one
meter_group and the following test and relationship of a Subscription worked
fine:
class Subscription < ActiveRecord::Base
belongs_to :user, :foreign_key => "user_id"
belongs_to :meter_group, :foreign_key => "meter_group_id"
has_many :meters, :through => :meter_group
end
test "group1 and group2 belong to rachel" do
user = User.find_by_login("rachel")
subscriptions = Subscription.find_all_by_user_id(user.id)
subscriptions.each do |s|
meters = s.meters
meters.each do |m|
puts "meter = #{p m}"
end
end
end
However now things are not working since I created some HABTM relationships
for meter_group and meters. I end up with the following error:
ActiveRecord::HasManyThroughSourceAssociationMacroError: Invalid source
reflection macro :has_and_belongs_to_many for has_many :meters, :through =>
:meter_group. Use :source to specify the source reflection.
Here are some of the other relevant tables and migrations (stripped of a few
non-related fields):
class MeterGroup < ActiveRecord::Base
belongs_to :user, :foreign_key => "user_id"
has_and_belongs_to_many :meters
end
class Meter < ActiveRecord::Base
has_and_belongs_to_many :meter_groups
belongs_to :user, :foreign_key => "user_id"
end
#Migrations (removed some cols and drop section)
class CreateMeterGroups < ActiveRecord::Migration
def self.up
create_table :meter_groups do |t|
t.string :name
t.string :description
t.integer :user_id
t.timestamps
end
end
end
class CreateMeters < ActiveRecord::Migration
def self.up
create_table :meters do |t|
t.integer :meter_type_id
t.integer :scale_id
t.integer :user_id
t.string :name
t.string :description
t.timestamps
end
end
end
class CreateMetersMeterGroups < ActiveRecord::Migration
def self.up
create_table :meter_groups_meters, :id => false do |t|
t.integer :meter_id
t.integer :meter_group_id
t.timestamps
end
end
end
class CreateSubscriptions < ActiveRecord::Migration
def self.up
create_table :subscriptions do |t|
t.integer :user_id
t.integer :meter_group_id
t.timestamps
end
end
end
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