Ruby 有条件的似乎没有得到评估

在Rails 4项目中，我有两个这样设置的模型

student.rb

class Student < ActiveRecord::Base
  has_many :contracts

  def balance
    unpaid_contracts.sum(&:sum_total)
  end

private

  def unpaid_contracts
    unpaid_contracts = []
    contracts.each do |c|
      unpaid_contracts << c if c.unpaid? # This is the problem
    end
  end

end

class Contract < ActiveRecord::Base

  has_many :invoices, dependent: :destroy
  belongs_to :student

  def unpaid?
    return true if invoices.blank?
    invoices.each do |i|
      return true if i.current_status != "paid" && i.current_status != "rescinded"
    end
  end
end

class-Student未支付的合同请注意您的回报值：

  def unpaid_contracts
    unpaid_contracts = []
    contracts.each do |c|
      unpaid_contracts << c if c.unpaid? # This is the problem
    end
  end

但这更好：

  def unpaid_contracts
    contracts.select(&:unpaid?)
  end

你能试试下面的吗

私有方法仅适用于不打算使用类或类的实例的情况，因此请尝试将其删除

略为简洁的编码方式：

def unpaid_contracts
   contracts.select { |contract| contract.invoices.count == 0}
end


正如@meagar所提到的，您没有返回正确的变量

您是否尝试过加载一个合同并使用
.unpaid？
它会返回什么？该代码对我来说似乎是这样的
contracts.select{| contract | contract.pending？}
感谢您对私有方法的指导！
def unpaid_contracts
   contracts.select { |contract| contract.invoices.count == 0}
end