ActiveRecordNestedScope
An ActiveRecord extension to build nested scopes through pre-defined associations.
Dependencies
- ruby 2.3+
- rails 5.0+ (activerecord and activesupport)
Installation
Add this line to your application's Gemfile:
gem 'activerecord_nested_scope'
Then execute:
$ bundle
Usage
For example, define in_group
scope using nested_scope as follows:
class Group < ActiveRecord::Base
nested_scope :in_group # root scope
...
end
class User < ActiveRecord::Base
belongs_to :group
nested_scope :in_group, through: :group # User belongs to Group
...
end
class UserConfig < ActiveRecord::Base
belongs_to :user
nested_scope :in_group, through: :user # UserConfig belongs to Group through User
...
end
in_group
scope generates SQL as follows:
User.in_group(id: 1)
#=> SELECT "users".* FROM "users" WHERE "users"."group_id" IN (
# SELECT "groups"."id" FROM "groups" WHERE "groups"."id" = 1)
UserConfig.in_group(id: 1)
#=> SELECT "user_configs".* FROM "user_configs" WHERE "user_configs"."user_id" IN (
# SELECT "users"."id" FROM "users" WHERE "users"."group_id" IN (
# SELECT "groups"."id" FROM "groups" WHERE "groups"."id" = 1))
Polymorphic association
If you define a polymorphic association like that,
class Name < ActiveRecord::Base
belongs_to :data, polymorphic: true
nested_scope :in_group, through: :data
end
in_group
scope generates union of subqueries for each polymorpchic type:
Name.in_group(id: 1)
#=> SELECT "names"."data_type" FROM "names" GROUP BY "names"."data_type"
# SELECT "names".* FROM (
# SELECT "names".* FROM "names" WHERE "names"."data_type" = 'Group' AND "names"."data_id" IN (SELECT "groups"."id" FROM "groups" WHERE "groups"."id" = 1) UNION
# SELECT "names".* FROM "names" WHERE "names"."data_type" = 'Manager' AND "names"."data_id" IN (SELECT "managers"."id" FROM "managers" WHERE "managers"."id" IN (SELECT "groups"."manager_id" FROM "groups" WHERE "groups"."id" = 1)) UNION
# SELECT "names".* FROM "names" WHERE "names"."data_type" = 'Supervisor' AND "names"."data_id" IN (SELECT "supervisors"."id" FROM "supervisors" WHERE "supervisors"."id" IN (SELECT "managers"."supervisor_id" FROM "managers" WHERE "managers"."id" IN (SELECT "groups"."manager_id" FROM "groups" WHERE "groups"."id" = 1) ORDER BY "managers"."id" ASC)) UNION
# SELECT "names".* FROM "names" WHERE "names"."data_type" = 'User' AND "names"."data_id" IN (SELECT "users"."id" FROM "users" WHERE "users"."group_id" IN (SELECT "groups"."id" FROM "groups" WHERE "groups"."id" = 1))) AS names
Note that the first SQL is executed to load data_type
, and the second SQL is built using loaded data_type
variations.
Scope examples
# pass a integer
User.in_group(1)
# pass a hash
User.in_group(id: 1)
# pass an AR relation
User.in_group(Group.where(id: 1))
Contributing
Bug reports and pull requests are welcome at https://github.com/kanety/activerecord_nested_scope.
License
The gem is available as open source under the terms of the MIT License.