Rails - 带有 heredoc 的 find_by_sql 引发错误答案

【问题标题】：Rails - find_by_sql with heredoc raises errorRails - 带有 heredoc 的 find_by_sql 引发错误
【发布时间】：2019-04-19 18:18:18
【问题描述】：

我在 heredoc 中有这个简单的 SQL

sql = <<-SQL
  SELECT SUM(price) as total_price, 
    SUM(distance) as total_distance, 
    TO_CHAR(date, 'YYYY-MM') as month
  FROM Rides
  WHERE user_id = #{current_user.id}
  GROUP_BY month
SQL

还有一个find_by_sql(sql) 电话

Ride.find_by_sql(sql).each do |row|
  "#{row.month}: { total_distance: #{row.total_distance}, total_price: #{row.total_price} }" 
end

它会引发错误：

ActiveRecord::StatementInvalid: PG::SyntaxError: ERROR:  syntax error at or near "GROUP_BY"
LINE 6:         GROUP_BY month
                ^
:         SELECT SUM(price) as total_price, 
          SUM(distance) as total_distance, 
          TO_CHAR(date, 'YYYY-MM') as month
        FROM Rides
        WHERE user_id = 1
        GROUP_BY month

如您所见，它对 user_id 进行了很好的插值，因此问题不在于插值。

如果我将此 SQL 作为字符串分配给变量，它会起作用，如下所示：

str = "select sum(distance) as total_distance, sum(price) as total_price, to_char(date, 'YYYY-MM') as month from rides where user_id = #{ current_user.id } group by month"

heredoc 有什么问题？

【问题讨论】：

标签： ruby-on-rails rails-activerecord heredoc find-by-sql

【解决方案1】：

SQL 有一个 GROUP BY 子句而不是 GROUP_BY。

sql = <<-SQL
  SELECT SUM(price) as total_price, 
    SUM(distance) as total_distance, 
    TO_CHAR(date, 'YYYY-MM') as month
  FROM Rides
  WHERE user_id = #{current_user.id}
  GROUP BY month
SQL

【讨论】：

Omg :D 我知道这很简单 :) 谢谢