Question

假设我在Rails方法中有一个这样的实例变量（稍后将使用）

def index
    @users = User.select("users.id as usr_id,
                          users.name as user_name,
                          users.first_price as price,
                          users.tax as tax,
 (#here's model method)=> users.sum_all as grand_total")
                        .where("users.deleted_at is null AND
                         users.id IN (?)
                         @users.pluck(:id))
                        .order(@order_by)
end

并且我想在此查询中实现一个看起来像这样的模型方法

User < ApplicationRecord
  def sum_all
    self.first_price + self.tax
  end
end

如果按上述方法放置此方法，则会出现错误

{"status":500,"error":"Internal Server Error","exception":"#\u003cActionView::Template::Error: Mysql2::Error: Unknown column 'users.sum_all' in 'field list'}

Answer 1

我建议您避免这样做。相反，您可以通过在查询本身中添加两个字段值来使上面的查询起作用。

def index
    @users = User.select("users.id as usr_id,
                          users.name as user_name,
                          users.first_price as price,
                          users.tax as tax,
                          users.first_price + users.tax as grand_total")
                 .where("users.deleted_at is null AND users.id IN (?)", @users.pluck(:id))
                 .order(@order_by)
end

如何在MySQL查询中调用模型方法？

1 个答案: