Module: Prioritize::PriorityAfter::ClassMethods

Defined in:
lib/prioritize.rb

Overview

Методы класса после расширения модулем PriorityAfter перечислены в этом подмодуле.

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#priority_column ⇒ Object

def priority_column=(value)

@priority_column = value

end



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# File 'lib/prioritize.rb', line 162

def priority_column
  @priority_column
end

#priority_nested ⇒ Object

def priority_column=(value)

@priority_column = value

end



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# File 'lib/prioritize.rb', line 162

def priority_nested
  @priority_nested
end

#priority_parent ⇒ Object

def priority_column=(value)

@priority_column = value

end



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# File 'lib/prioritize.rb', line 162

def priority_parent
  @priority_parent
end

Class Method Details

.extended(base) ⇒ Object 



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# File 'lib/prioritize.rb', line 164

def self.extended(base)
  base.class_eval do
    # @priority_column = :priority
  end
end

Instance Method Details

#priority_after(prev_id, moved_id) ⇒ Object 



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# File 'lib/prioritize.rb', line 70

def priority_after(prev_id, moved_id)
  if connection.adapter_name == 'SQLite'
    priority_sqlite(prev_id, moved_id)
  else
    connection.exec_query(
      priority_sql,
      'priority_after',
      [[nil, prev_id], [nil, moved_id]]
    )
  end
end

#priority_sql ⇒ Object 



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# File 'lib/prioritize.rb', line 82

def priority_sql
  sql = <<-SQL
    UPDATE #{table_name} o
    SET "#{priority_column}" = ordered.rn
    FROM (
      SELECT *, ROW_NUMBER() OVER() AS rn
      FROM (
        -- Выбрать записи от начала и до предыдущего (включая его),
        -- конечно исключая перемещаемую запись.
        (
          SELECT o.*
          FROM #{table_name} o
          LEFT JOIN #{table_name} prev ON prev.id IS NOT DISTINCT FROM $1
          LEFT JOIN #{table_name} moved ON moved.id IS NOT DISTINCT FROM $2
          WHERE
            o."#{priority_column}" <= prev."#{priority_column}"
            AND o.id <> $2
            nested_condition
          ORDER BY o."#{priority_column}" ASC
        )
        UNION ALL
        -- Выбрать перемещаемую запись.
        (
          SELECT o.*
          FROM #{table_name} o
          WHERE o.id = $2
        )
        UNION ALL
        -- Выбрать от предыдущего (не включая его) и до конца, так же
        -- исключая перемещаемую запись.
        (
          SELECT o.*
          FROM #{table_name} o
          LEFT JOIN #{table_name} prev ON prev.id IS NOT DISTINCT FROM $1
          LEFT JOIN #{table_name} moved ON moved.id IS NOT DISTINCT FROM $2
          WHERE
            (o."#{priority_column}" > prev."#{priority_column}" OR prev."#{priority_column}" IS NULL)
            AND o.id <> $2
            nested_condition
          ORDER BY o."#{priority_column}" ASC
        )
      ) numbered
    ) ordered
    WHERE  o.id = ordered.id
  SQL
  nested_condition = priority_nested ?
    %Q(AND o."#{priority_parent}" IS NOT DISTINCT FROM moved."#{priority_parent}") :
    ''
  sql.gsub! 'nested_condition', nested_condition
  sql
end

#priority_sqlite(prev_id, moved_id) ⇒ Object 



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# File 'lib/prioritize.rb', line 134

def priority_sqlite(prev_id, moved_id)
  list = select('id', "#{priority_column}").order("#{priority_column}" => :asc).where.not(id: moved_id).to_a
  moved = select('id', "#{priority_column}").find_by_id(moved_id)
  if prev_id.nil?
    list.unshift(moved)
  else
    list.each_with_index do |model, index|
      if model.id.to_s == prev_id
        list.insert(index + 1, moved)
        break
      end
    end
  end
  transaction do
    list.each_with_index do |model, index|
      model.update("#{priority_column}" => index)
    end
  end
end