Question

我正在尝试为我的rails应用程序编写更多的模块化代码，因此已经开始在类中包含模块。我对它们的功能有基本的了解，但我发现在保持DRY的同时很难让它们保持灵活性。

这是一个当前的例子。

我有一个名为Contactable的模块。它有两个非常基本的功能。

确保数据库中存在正确的联系人列。
验证某些字段。

这是

module Contactable
  extend ActiveSupport::Concern
  ERROR = 'please ensure necessary fields are in place'

  included do
    REQUIRED_DATABASE_FIELDS.map { |rdf| raise "#{rdf} not included. #{ERROR}" unless column_names.include?(rdf)}
    REQUIRED_INPUT_FIELDS.map { |rif| validates rif.to_sym, presence: true}
  end
end

我希望可以联系其他三个模块（可电话，可电子邮件和可寻址），其中包含要求的列数组和要验证的字段。我现在正在研究的是“可寻址的”

module Addressable 
  extend ActiveSupport::Concern
  ERROR = 'please ensure necessary fields are in place'

  REQUIRED_DATABASE_FIELDS = %w{address1 
                                address2 
                                address3 
                                town 
                                county 
                                country 
                                postcode}

  REQUIRED_INPUT_FIELDS = %w{address1 postcode}

  included do
    REQUIRED_DATABASE_FIELDS.map { |rdf| raise "#{rdf} not included. #{ERROR}" unless column_names.include?(rdf)}
    REQUIRED_INPUT_FIELDS.map { |rif| validates rif.to_sym, presence: true}
  end
end

显然这里有重复。但是，如果我将此模块包含在可联系中，我可以避免重复某些操作，但这意味着Contactable将始终包含Phoneable和Emailable。在某些情况下，我可能不想验证或要求这些特征。有没有办法可以实现这种灵活性？

Answer 1

您可以这样做：

添加 /app/models/concerns/fields_validator.rb

module FieldsValidator
  extend ActiveSupport::Concern

  class_methods do
    def validate_required_attributes
      required_attributes.each do |a|
        puts "adds validation for #{a}"
        validates(a.to_sym, presence: true)
      end
    end

    def load_required_attributes(*_attrs)
      puts "loading attrs: #{_attrs.to_s}"
      @required_attributes ||=[]
      @required_attributes += _attrs
      @required_attributes.uniq!
    end

    def required_attributes
      @required_attributes
    end
  end
end

添加 /app/models/concerns/contact.rb

module Contact
  extend ActiveSupport::Concern
  include FieldsValidator

  included do
    puts "include contact..."
    load_required_attributes(:product_details, :observations, :offer_details)
  end
end

添加 /app/models/concerns/address.rb

module Address
  extend ActiveSupport::Concern
  include FieldsValidator

  included do
    puts "include address..."
    load_required_attributes(:sku, :amount, :observations)
  end
end

在模型中......

class Promotion < ActiveRecord::Base
  include Address
  include Contact

  validate_required_attributes
end

输出：

include address...
loading attrs: [:sku, :amount, :observations]
include contact...
loading attrs: [:product_details, :observations, :offer_details]
adds validation for sku
adds validation for amount
adds validation for observations
adds validation for product_details
adds validation for offer_details

要检查这是否有效......

Promotion.new.save!
"ActiveRecord::RecordInvalid: Validation failed: Sku can't be blank, Amount can't be blank, Observations can't be blank, Product details can't be blank, Offer details can't be blank"

<强>考虑：

将您的模块保存在自定义命名空间中。您将遇到现有Addressable模块的问题。例如：

module MyApp
  module Addressable
  # code...
  end
end

class Promotion < ActiveRecord::Base
  include MyApp::Addressable

  validate_required_attributes
end

您需要先加载所有属性，然后应用验证。如果你不这样做，你可以在模块共享属性时重复验证。
共享逻辑进入FieldsValidator模块

Answer 2

你应该在这里使用单元测试。通过从模型（或它们包含的模块）检查数据库模式，您并没有真正实现任何目标。如果列不存在，则应用程序将抛出NoMethodError或数据库驱动程序错误。

实际上有更好的单元测试可以覆盖你的模型并确保它们按预期工作。

require 'rails_helper'

describe User
  # Tests the presence of the database column indirectly. 
  it { should respond_to :email }

  # Explicit test - there a very few good reasons to actually do this.
  it "should have the email column" do
    expect(User.column_names).to have_key :email 
  end
end

如果您使用的是RSpec，则可以使用共享示例来减少规格中的重复次数。

# support/example_groups/addressable.rb
require 'spec_helper'
RSpec.shared_examples_for "an addressable" do
  it { should respond_to :address1 }
  it { should respond_to :address2 }
  it { should respond_to :address3 } 
  it { should respond_to :county } 
  it { should respond_to :postcode } 
  # ...
end

require 'rails_helper'
require 'support/example_groups/addressable'

describe User
  it_should_behave_like "an addressable"
end

有关如何使用test_unit / minitest实现相同功能的示例，请参阅How do i get RSpec's shared examples like behavior in Ruby Test::Unit?。

Rails / Ruby，混合模块和剩余DRY

2 个答案: