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require 'active_support/concern'
module ActiveRecord
module Scoping
extend ActiveSupport::Concern
included do
include Default
include Named
end
module ClassMethods
# with_scope lets you apply options to inner block incrementally. It takes a hash and the keys must be
# <tt>:find</tt> or <tt>:create</tt>. <tt>:find</tt> parameter is <tt>Relation</tt> while
# <tt>:create</tt> parameters are an attributes hash.
#
# class Article < ActiveRecord::Base
# def self.create_with_scope
# with_scope(:find => where(:blog_id => 1), :create => { :blog_id => 1 }) do
# find(1) # => SELECT * from articles WHERE blog_id = 1 AND id = 1
# a = create(1)
# a.blog_id # => 1
# end
# end
# end
#
# In nested scopings, all previous parameters are overwritten by the innermost rule, with the exception of
# <tt>where</tt>, <tt>includes</tt>, and <tt>joins</tt> operations in <tt>Relation</tt>, which are merged.
#
# <tt>joins</tt> operations are uniqued so multiple scopes can join in the same table without table aliasing
# problems. If you need to join multiple tables, but still want one of the tables to be uniqued, use the
# array of strings format for your joins.
#
# class Article < ActiveRecord::Base
# def self.find_with_scope
# with_scope(:find => where(:blog_id => 1).limit(1), :create => { :blog_id => 1 }) do
# with_scope(:find => limit(10)) do
# all # => SELECT * from articles WHERE blog_id = 1 LIMIT 10
# end
# with_scope(:find => where(:author_id => 3)) do
# all # => SELECT * from articles WHERE blog_id = 1 AND author_id = 3 LIMIT 1
# end
# end
# end
# end
#
# You can ignore any previous scopings by using the <tt>with_exclusive_scope</tt> method.
#
# class Article < ActiveRecord::Base
# def self.find_with_exclusive_scope
# with_scope(:find => where(:blog_id => 1).limit(1)) do
# with_exclusive_scope(:find => limit(10)) do
# all # => SELECT * from articles LIMIT 10
# end
# end
# end
# end
#
# *Note*: the +:find+ scope also has effect on update and deletion methods, like +update_all+ and +delete_all+.
def with_scope(scope = {}, action = :merge, &block)
# If another Active Record class has been passed in, get its current scope
scope = scope.current_scope if !scope.is_a?(Relation) && scope.respond_to?(:current_scope)
previous_scope = self.current_scope
if scope.is_a?(Hash)
# Dup first and second level of hash (method and params).
scope = scope.dup
scope.each do |method, params|
scope[method] = params.dup unless params == true
end
scope.assert_valid_keys([ :find, :create ])
relation = construct_finder_arel(scope[:find] || {})
relation.default_scoped = true unless action == :overwrite
if previous_scope && previous_scope.create_with_value && scope[:create]
scope_for_create = if action == :merge
previous_scope.create_with_value.merge(scope[:create])
else
scope[:create]
end
relation = relation.create_with(scope_for_create)
else
scope_for_create = scope[:create]
scope_for_create ||= previous_scope.create_with_value if previous_scope
relation = relation.create_with(scope_for_create) if scope_for_create
end
scope = relation
end
scope = previous_scope.merge(scope) if previous_scope && action == :merge
self.current_scope = scope
begin
yield
ensure
self.current_scope = previous_scope
end
end
protected
# Works like with_scope, but discards any nested properties.
def with_exclusive_scope(method_scoping = {}, &block)
if method_scoping.values.any? { |e| e.is_a?(ActiveRecord::Relation) }
raise ArgumentError, <<-MSG
New finder API can not be used with_exclusive_scope. You can either call unscoped to get an anonymous scope not bound to the default_scope:
User.unscoped.where(:active => true)
Or call unscoped with a block:
User.unscoped do
User.where(:active => true).all
end
MSG
end
with_scope(method_scoping, :overwrite, &block)
end
def current_scope #:nodoc:
Thread.current["#{self}_current_scope"]
end
def current_scope=(scope) #:nodoc:
Thread.current["#{self}_current_scope"] = scope
end
private
def construct_finder_arel(options = {}, scope = nil)
relation = options.is_a?(Hash) ? unscoped.apply_finder_options(options) : options
relation = scope.merge(relation) if scope
relation
end
end
def populate_with_current_scope_attributes
return unless self.class.scope_attributes?
self.class.scope_attributes.each do |att,value|
send("#{att}=", value) if respond_to?("#{att}=")
end
end
end
end
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