Question

我有以下方法：

def self.sap_qualified(start_at, stop_at, zip)
    course_ids = Course.where('sap_qualifying IS true OR sap_renewing IS true').collect{|c| c.id}
    if course_ids.any?
      course_class_ids = CourseClass.where(course_id: course_ids).collect{|c| c.id}
      if course_class_ids.any?
        joins(:class_registrations).
        joins(:primary_billing).where("postal_code =?", zip).
        where(:class_registrations => {course_class_id: course_class_ids}).
        where('class_registrations.score ~ ? AND CAST(class_registrations.score as int) >= ? AND class_registrations.exam_completed_at >= ? AND class_registrations.exam_completed_at <= ?', '^[0-9]', 80, start_at.to_date.beginning_of_day, stop_at.to_date.beginning_of_day)
      else
...

...如果用户包含邮政编码（第三个参数），则可以预期该方法有效。但是，如果用户将邮政编码字段留空，则我想在不使用邮政编码的join语句的情况下运行查询。

我可以做类似的事情

if !zip.blank?
  one query...
else
  same query as above, but with the joins(:primary_billing).where("postal_code =?", zip)...

...但是那感觉很古怪，并且违反了大约十二个DRY主体。

Answer 1

查询中的每个ActiveRecord语句都返回一个Relation，您可以将其保存到中间变量：

  if course_class_ids.any?
    relation = joins(:class_registrations)

    if zip.present?        
      relation = relation.joins(:primary_billing).where("postal_code =?", zip)
    end

    relation = relation.where(:class_registrations => {course_class_id: course_class_ids}).
    where('class_registrations.score ~ ? AND CAST(class_registrations.score as int) >= ? AND class_registrations.exam_completed_at >= ? AND class_registrations.exam_completed_at <= ?', '^[0-9]', 80, start_at.to_date.beginning_of_day, stop_at.to_date.beginning_of_day)
  else

如果方法参数为空，则忽略连接

1 个答案: