Rails 3.获取相关模型的属性

Question

我有两种模式：注册和发票。

enrollment belongs to invoice
invoice has many enrollments

所以我有这个查询：@enrollments = Enrollment.where('invoice_id IS NOT NULL')来获取属于发票的所有注册。

但是我需要进行某种类型的连接，因为我真正想要的是具有相关注册的发票（id，invoice_number和totals）。

我该怎么做？

到目前为止我在控制台中尝试了什么...

enrollments = Enrollment.where('invoice_id IS NOT NULL').joins(:invoice)
enrollments.each do |enrollment|
  puts enrollment.invoice_number
end

我得到NoMethodError: undefined method invoice_number for #<Enrollment:0x00000006a1e1a8>，因为我只能访问发票的ID。

Answer 1

Invoice.joins(:enrollments).uniq