mastodon-glitch/lib/active_record/with_recursive.rb

66 lines
2.1 KiB
Ruby

# frozen_string_literal: true
# Add support for writing recursive CTEs in ActiveRecord
# Initially from Lorin Thwaits (https://github.com/lorint) as per comment:
# https://github.com/vlado/activerecord-cte/issues/16#issuecomment-1433043310
# Modified from the above code to change the signature to
# `with_recursive(hash)` and extending CTE hash values to also includes arrays
# of values that get turned into UNION ALL expressions.
# This implementation has been merged in Rails: https://github.com/rails/rails/pull/51601
module ActiveRecord
module QueryMethodsExtensions
def with_recursive(*args)
@with_is_recursive = true
check_if_method_has_arguments!(__callee__, args)
spawn.with_recursive!(*args)
end
# Like #with_recursive but modifies the relation in place.
def with_recursive!(*args) # :nodoc:
self.with_values += args
@with_is_recursive = true
self
end
private
def build_with(arel)
return if with_values.empty?
with_statements = with_values.map do |with_value|
raise ArgumentError, "Unsupported argument type: #{with_value} #{with_value.class}" unless with_value.is_a?(Hash)
build_with_value_from_hash(with_value)
end
# Was: arel.with(with_statements)
@with_is_recursive ? arel.with(:recursive, with_statements) : arel.with(with_statements)
end
def build_with_value_from_hash(hash)
hash.map do |name, value|
Arel::Nodes::TableAlias.new(build_with_expression_from_value(value), name)
end
end
def build_with_expression_from_value(value)
case value
when Arel::Nodes::SqlLiteral then Arel::Nodes::Grouping.new(value)
when ActiveRecord::Relation then value.arel
when Arel::SelectManager then value
when Array then value.map { |e| build_with_expression_from_value(e) }.reduce { |result, value| Arel::Nodes::UnionAll.new(result, value) }
else
raise ArgumentError, "Unsupported argument type: `#{value}` #{value.class}"
end
end
end
end
ActiveSupport.on_load(:active_record) do
ActiveRecord::QueryMethods.prepend(ActiveRecord::QueryMethodsExtensions)
end