干燥Rails控制器代码以进行数据导出

Question

Not sure if this is an appropriate question so forgive me.

I have the following code in a controller action

unless @users.empty?
  book = Spreadsheet::Workbook.new
  sheet1 = book.create_worksheet :name => 'export'
  sheet1.row(0).concat ["Label1", "Label2", "Label3"]
  @users.each_with_index do |e, i|
    sheet1.row(i+1).concat([e.field1, e.field2, e.field3])
  end
  require 'stringio'
  data = StringIO.new ''
  book.write data
  send_data data.string, :type=>"application/excel", :disposition=>'attachment', :filename => "export_#{l(Date.today)}.xls"
end

This allows me to have a button on a form that runs an export. Whilst this is very useful, I am using this code all over the place. In fact, I have 19 instances of this code across various controllers in the app. Is there a way I can move this code to another file, and pass into it a hash of the labels and fields so that I only have to maintain one instance of the export code?

thanks

Answer 1

Basic of MVC is to have as much as skinnier controllers, and your case is perfect example, to prevent to repeat your code.

Solution for this is to move your code to models the M in the MVC pattern, it is responsible for all the business logic.

Move this method to the module . In app/models/concers/ folder create new file sheetable.rb

require 'active_support/concern'

module Sheetable
  extend ActiveSupport::Concern

  module ClassMethods    
    def new_sheet objects
      unless objects.empty?
        book = Spreadsheet::Workbook.new
        sheet1 = book.create_worksheet :name => 'export'
        sheet1.row(0).concat ["Label1", "Label2", "Label3"]
        objects.each_with_index do |e, i|
          sheet1.row(i+1).concat([e.field1, e.field2, e.field3])
        end
        require 'stringio'
        data = StringIO.new ''
        book.write data    
      end
    end
  end
end

Now include module in your model and it will have class method new_sheet .

class User < ActiveRecord::Base
  ...
  include Sheetable
  ...
end

or in other model

class OtherModel < ActiveRecord::Base
  ...
  include Sheetable
  ...
end

To use this

data = User.new_sheet(@users) # or OtherModel.new_sheet(@other_models)
if data
 send_data data.string, :type=>"application/excel", :disposition=>'attachment', :filename => "export_#{l(Date.today)}.xls"
end

Now you have moved the logic to the model next step is to refactor this method, make it more simpler.

Answer 2

I'd begin with moving the code to where the responsibility belongs. It seems that you're exporting data of a certain set of users to a spreadsheet. So I'd move the code to the User class, eg

def self.export_subset_to_spreadsheet(users)
  ... your code ...
end

and then call it from your controller with User.export_subset_to_spreadsheet(@users) .

This is step one. You can certainly take it further from there, but at least this allows you to get rid of the most pressing problem: the 19 duplications of that whole block of code.