method

add_order_by_for_association_limiting!

v1.2.0 - Show latest stable - 0 notes - Class: ActiveRecord::ConnectionAdapters::PostgreSQLAdapter

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What's this?

add_order_by_for_association_limiting!(sql, options) public

ORDER BY clause for the passed order option.

PostgreSQL does not allow arbitrary ordering when using DISTINCT ON, so we work around this by wrapping the sql as a sub-select and ordering in that query.

Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 408
      def add_order_by_for_association_limiting!(sql, options)
        return sql if options[:order].blank?
        
        order = options[:order].split(',').collect { |s| s.strip }.reject(&:blank?)
        order.map! { |s| 'DESC' if s =~ /\bdesc$/i }
        order = order.zip((0...order.size).to_a).map { |s,i| "id_list.alias_#{i} #{s}" }.join(', ')
        
        sql.replace "SELECT * FROM (#{sql}) AS id_list ORDER BY #{order}"
      end

add_order_by_for_association_limiting!

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