Question

将我的控制器中的方法（Invoices）移动到相应的模型中，我遗漏了一些东西。我已尝试关注this和this甚至是this，并且我遇到了一些我需要额外关注的小问题。

我的工作控制器方法就是这样。

  def array_of_disbursable_invoices
    sql = "SELECT MIN(departure_date), ch_invoice.invoice_id
    FROM ch_invoice
    INNER JOIN ch_trip
    ON ch_invoice.invoice_id = ch_trip.invoice_id
    WHERE departure_date <= (SELECT SYS_EXTRACT_UTC(SYSTIMESTAMP)FROM DUAL)
    AND service_rendered = 0
    AND paid = 1
    Group By ch_invoice.invoice_id"

    report = ActiveRecord::Base.connection.exec_query(sql)
    render json: report
  end

我正试图把它变成这个。

  def array_of_disbursable_invoices
    report = report.array_of_disbursable_invoices
    render json: report
  end

我的模型中有逻辑。

  def array_of_disbursable_invoices
    sql = "SELECT MIN(departure_date), ch_invoice.invoice_id
    FROM ch_invoice
    INNER JOIN ch_trip
    ON ch_invoice.invoice_id = ch_trip.invoice_id
    WHERE departure_date <= (SELECT SYS_EXTRACT_UTC(SYSTIMESTAMP)FROM DUAL)
    AND service_rendered = 0
    AND paid = 1
    Group By ch_invoice.invoice_id"

    ActiveRecord::Base.connection.exec_query(sql)
  end

当前错误消息

未定义的方法`array_of_disbursable_invoices'为nil：NilClass

Answer 1

你打败了我（基本上，我的第二个选择）。但是，无论如何我都会发布这个。

执行此操作时：

def array_of_disbursable_invoices
  report = report.array_of_disbursable_invoices
  render json: report
end

您在实例上调用array_of_disbursable_invoices。但是，您没有实例化Report - 因此，undefined method 'array_of_disbursable_invoices' for nil:NilClass错误。

所以，我认为你有两个选择：

（1）您可以在实例上调用该方法，例如：

report = Invoice.new.array_of_disbursable_invoices

（2）您可以将该方法设为类方法，例如：

class Invoice < ActiveModel::Base
  class << self
    def array_of_disbursable_invoices
      sql = "SELECT MIN(departure_date), ch_invoice.invoice_id
      FROM ch_invoice
      INNER JOIN ch_trip
      ON ch_invoice.invoice_id = ch_trip.invoice_id
      WHERE departure_date <= (SELECT SYS_EXTRACT_UTC(SYSTIMESTAMP)FROM DUAL)
      AND service_rendered = 0
      AND paid = 1
      Group By ch_invoice.invoice_id"

      connection.exec_query(sql)
    end
  end
end

我想我推荐（1）。另外，就个人而言，我使用ActiveRecord查询接口而不是SQL（假设您在模型中设置了所有关联）。但是，这是个人偏好。

Answer 2

在控制器中使用以下代码。

  def array_of_disbursable_invoices
    report = Invoice.array_of_disbursable_invoices
    render json: report
  end

这在模型中。

  def self.array_of_disbursable_invoices
    sql = "SELECT MIN(departure_date), ch_invoice.invoice_id
    FROM ch_invoice
    INNER JOIN ch_trip
    ON ch_invoice.invoice_id = ch_trip.invoice_id
    WHERE departure_date <= (SELECT SYS_EXTRACT_UTC(SYSTIMESTAMP)FROM DUAL)
    AND service_rendered = 0
    AND paid = 1
    Group By ch_invoice.invoice_id"

    ActiveRecord::Base.connection.exec_query(sql)
  end

使用SQL移动方法逻辑以在rails项目中建模

2 个答案: