Question

我想在我的rails应用程序中为模型创建类似新订单方法的东西。此订单方法应该能够将记录与一列进行比较。在列表的开头应该是具有该列的最高（> 250）和最低（<80）值的记录，而其他（具有80到250之间的平均值）的记录应该在列表的末尾。是否可以在铁轨中进行？

Answer 1

使用普通红宝石

# when order between 0 - 80 and > 250 does not matter
YourModel.all.to_a.sort_by do  |record| 
   if record.order_col < 80 || record.order_col >250
     0 
   else
     1
   end
end

# when order between 0 - 80 and > 250 does matter
YourModel.all.to_a.sort_by do  |record| 
   if record.order_col < 80 || record.order_col >250
     record.order_col
   else
     record.order_col + YourModel.max(:order_col) + 1
   end
end

使用SQL

# with sql

scope :ordered, find_by_sql(%(
  SELECT your_model.* FROM your_model where value < 80 OR value > 250 ORDER BY id desc
  UNION
  SELECT your_model.* FROM your_model where value >= 80 and value <= 250 ORDER BY id desc
 ))

# can work with mysql
YourModel.select(:field, ..., 'IF (column < 80 OR column > 250, column, column + (SELECT max(column) FROM yourtable ) + 1) as order_column').order('order_column desc')

在Rails中是否可以为模型创建自定义顺序方法？

1 个答案: