将 SQL 的方法逻辑移动到 rails 项目中的模型

Question

将我的控制器 (Invoices) 中的一个方法移动到相应的模型中，但我遗漏了一些东西。我已经尝试关注 this and and even this，但我遇到了一些小问题，需要多加注意。

我的工作控制器方法是这样的。

  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

我正在努力把它变成这个。

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

在这里使用我模型中的逻辑。

  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

当前错误信息

undefined method `array_of_disbursable_invoices' for nil:NilClass

Answer 1

让它在我的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

模型中也是如此。

  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

Answer 2

你先于我（并且基本上选择了我的第二个选项）。但是，无论如何我都会post这个。

当你这样做时：

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

您正在对实例调用 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) 您可以将方法设为 class 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

我想我会推荐 (1)。另外，就我个人而言，我会使用 ActiveRecord 查询接口而不是 SQL（假设您已经在模型中设置了所有关联）。但是，这是个人喜好。

将 SQL 的方法逻辑移动到 rails 项目中的模型

Moving method logic with SQL to model in rails project

ruby

refactoring

controller

model

ruby-on-rails