Question

我有一个现有的Rails 2.3.x应用程序，它使用以下代码块来总结给定数据范围的4列数据。

results = connection.execute(<<-SQL)
  SELECT sum(total_hours), sum(expected_hours), sum(total_billable), sum(expected_billable)
  FROM `timesheets`
  WHERE (`timesheets`.`week_starting` BETWEEN '#{Date.today.beginning_of_year}' AND '#{Date.today.monday}')
SQL
total_hours, expected_hours, total_billable, expected_billable = results.fetch_row.map(&:to_f).map(&:to_d)

当我升级到Rails 3和mysql2时，fetch_row方法不再存在，所以我认为这是使用ARel整理这个查询的好机会。

有人知道如何使用ARel进行此查询吗？

Answer 1

以模块化“构建器”样式编写，允许重构为可重用的范围：

Timesheet.where('week_starting >= ?', Date.today.beginning_of_year).
  where('week_starting < ?', Date.today.monday).
  select('SUM(total_hours) as total_hours').
  select('SUM(expected_hours) as expected_hours').
  select('SUM(total_billable) as total_billable').
  select('SUM(total_hours) as expected_billable')

Answer 2

您可以像这样简化where子句：

date_range = Date.today.beginning_of_year..Date.today.monday
Timesheet.where(:week_starting => date_range).

这将成为BETWEEN条款。

使用ARel整理查询

2 个答案: