ActiveRecord association inheritance

Makes models inherit specified attributes from an association.
Scope queries by inherited attributes

Supports ActiveRecord 3.2, 4.1, 4.2, 5.0

Install

gem install active_record_inherit_assoc

Usage

Filling inherited attributes on initialization:

# parent_name - The Symbol name of the parent association.
# options     - The Hash options to use:
#               :attr - A Symbol or an Array of Symbol names of the attributes
#                       that should be inherited from the parent association.
#
class Post < ActiveRecord::Base
  belongs_to :category
  inherits_from :category, attr: :account
end

Scoping queries

class Post < ActiveRecord::Base
  has_many :categories, inherit: :account_id
end

post = Post.first
post.categories.build.account_id == post.account_id # fills attribute on new objects
post.categories.to_sql # adds inherited attributes to queries

This is similar to adding a scope { |record| where(account_id: record.account_id) }, but also allows to do Post.all.includes(:categories) to work by filtering preloaded records. This will not use the attribute to query, so it might use a different index and find more than neccessary records.

Copyright and license

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

Author

Ben Osheroff ben@gimbo.net