or_scopes.rb

# OR support for rails 4
module OrScopes
  extend ActiveSupport::Concern

  module ClassMethods
    # Creates a new scope with with all where clauses joined by "OR"
    # Preserves joins but ignores all other query elements.
    def or_scopes(scopes, use_joins: true)
      joins = []
      wheres = []
      scopes.each do |scope|
        joins_values = scope.joins_values

        joins += scope.joins_values if joins_values.present?

        scope_wheres = scope.where_values.map do |where_value|
          if where_value.is_a?(Arel::Nodes::Equality) || where_value.is_a?(Arel::Nodes::NotEqual)
            right = where_value.right
            if right.is_a?(Arel::Nodes::BindParam)
              left = where_value.left
              relation_table_name = left.relation.name
              where_values_hash = scope.where_values_hash(relation_table_name)

              where_value.right = Arel::Nodes.build_quoted(where_values_hash[left.name], scope.table[left.name])
            end
            where_value.to_sql
          else
            where_value
          end
        end

        wheres << "(#{ scope_wheres.join(' AND ') })"
      end
      scope = where(wheres.join(' OR '))
      scope = joins.inject(scope, &:joins) if use_joins
      scope
    end
  end
end